Safety summary

What happened

On 6 August 2015, TasRail northbound intermodal freight train 532, travelling from Boyer (near Hobart, Tasmania) to Burnie derailed on a section of track near Nala. The train consisted of two locomotives hauling 34 wagons. The train had an overall length of 557.8 m and a trailing mass 1,345.3 t. The driver was uninjured, but there was significant damage to rolling stock and about 200 m of track was destroyed.

What the ATSB found

The ATSB investigation determined that the leading wheelset on the front bogie of container wagon TQMF03G, derailed at the 95.185 km point south (kps). After the wagon derailed, the train travelled a further 2.3 km before it came to a stand.

Post-derailment measurements identified a series of track geometry defects in advance of the point of derailment (PoD). The largest defect exceeded safety limits specified in TasRail’s Track and Structure Maintenance Standard (INF-TS-211). A review of maintenance records found that a defect was identified (near the PoD) three days before the derailment. The defect was categorised as priority 1 requiring immediate attention, but did not result in the maintenance response specified by the standard.

The ATSB also identified that the track through the area had an elevated risk for geometry defects. Difficulty in maintaining track geometry through the area was probably related to poor track formation, ballast quality and the use of steel sleepers, which demand considerable maintenance effort to hold track alignment. However, there was no record of the track having been identified as a hazardous location, so it had not attracted greater analysis focus or maintenance attention.

Computer modelling showed that the TQMF wagons (compare to TQAY wagons) were more susceptible to derailment at a critical speed of 36 km/h, when traversing the track irregularity as existed at the derailment site.

What's been done as a result

TasRail have implemented a range of initiatives to reduce the risk of a similar occurrence including, changes to operational and maintenance procedures, enhanced strategies for responding to twist defects, and the consideration of fitting constant contact side bearers to the TQMF wagon fleet.

Safety message

Early detection, assessment and effective management of track defects are critical in minimising the risk of derailment and maintaining safe rail operations.

Derailed portion of train 532

Source: ATSB

Sources and submissions

Sources of information

The sources of information during the investigation included:

• TasRail

References

• ARA Glossary for the National Codes of Practice and Dictionary of Railway Terminology
• Bureau of Meteorology - Weather Observations for Tunnack, Tasmania (6 August 2015)
• Steel Sleeper Introduction on NSW Class 1 Main Line Track.1996 - 2004 (OTSI File Ref: 02619)
• RISSB Glossary of Railway Terminology – Guideline
• RO-2013-012 – Derailment of train 331 near Lowdina, Tasmania on 9 April 2013
• RO-2015-001– Derailment of TasRail train 135, Kimberley, Tasmania on 25 January 2015
• TasRail – Track and Structure Maintenance Standard (INF-TS-211) Ver 2.0 dated 26 August 2014

Submissions

Under Part 4, Division 2 (Investigation Reports), Section 26 of the Transport Safety Investigation Act 2003, the ATSB may provide a draft report, on a confidential basis, to any person whom the ATSB considers appropriate. Section 26 (1) (a) of the Act allows a person receiving a draft report to make submissions to the ATSB about the draft report.

A draft of this report was provided to:

• Driver of train 532
• Office of National Rail Safety Regulator
• TasRail

Submissions were received from the Office of the National Rail Safety Regulator, and TasRail. The submissions were reviewed and where considered appropriate, the text of the report was amended accordingly.

Context

Location

The derailment occurred near Nala, which is about 98 km north by rail from Hobart, Tasmania (Figure 1). The track, (south line) connects the north and south of Tasmania.

TasRail own and manage the network, and are based in Launceston.

Track information

The track from Boyer (near Hobart) through to Burnie substantially comprises a single line with crossing loops strategically located throughout its length. Authority to travel between sections was by way of a track warrant.

The derailment occurred near Nala, midway between Campania and Conara Junction, (Figure 1) about 98 km north by rail from Hobart, on the south line. The track through the derailment site consisted of narrow gauge (1,067 mm), 41 kg/m rail, mounted on steel sleepers, with resilient fasteners (E Clips) on a nominal 100 mm bed of ballast. Axle loads were limited to a maximum of 18 t. The track leading into the derailment site was on a downgrade of 1:83 (Figure 4) through a nominal 200 m radius left-hand curve (direction of train travel). The track speed limit through the derailment site was 40 km/h and there was no temporary speed restriction (TSR) in place.

Figure 4: Curve and gradient chart, showing Point of Derailment (PoD)

Source: TasRail, annotation ATSB

Environmental conditions

The closest weather station was located at Tunnack, about 24 km north of Nala. On the day of the derailment, the maximum temperature recorded at Tunnack was 8.1°C, and there was no rainfall recorded in the 24-hour period preceding the derailment. At the time of derailment, the weather was fine and cool, probably about 0°C. It is unlikely that weather was a factor that contributed to the derailment.

Train and train driver information

Train 532 was a regular TasRail intermodal freight service, carrying newsprint and empty shipping containers. The service operated between Boyer, near Hobart (Tasmania) and the port of Burnie in the north. Train 532 comprised two locomotives (TR15 leading and TR13 trailing) hauling 34 wagons. The train had an overall length of 557.8 m and a trailing mass 1,345.3 t. It was loaded and marshalled in accordance with TasRail requirements: heavy wagons were towards the front and empty wagons towards the rear.

The lead locomotive of train 532 stopped about 2,640 m past the point of derailment. The eighteen wagons that derailed were positioned 14 – 31 (inclusive) behind the locomotives.

Rolling stock

The majority of wagons (TQAYs) were about one year old and in as new condition. The remaining wagons (TQMF/QM and IB) were refurbished, and considered to be in good condition, and fit for purpose. A post-derailment inspection confirmed that the wagons, (wheels, suspension elements, springs, friction wedges and wear surfaces) were generally in good condition and in compliance with TasRail’s engineering tolerances.

The first seven derailed wagons showed very little in the way of wheel tread damage. Considering the distance from the point of derailment, the lack of damage suggested that they were not part of the initial derailment.

The first wheelset to show significant tread damage (Figure 5 and Figure 6), consistent with a wheelset riding on ballast over an extended distance, was wagon TQMF03G. It was concluded that wagon TQMF03G, located at position 21, was likely to have derailed first. The wagons ahead of TQMF03G (positions 14 to 20) had probably derailed later in the sequence, as train 532 negotiated a number of tight curves.

Figure 5: TQMY03G – Leading bogie, leading wheelset, right wheel (direction of train travel) showing evidence of extensive of tread damage

Source: ATSB

Figure 6: Derailed wagon TQMY03G (looking north) showing final positioning of bogies

Source: ATSB

At the time of derailment, wagon TQMF03G had an overall length of 16.7 m and gross mass of 47.69 t. The wagon was carrying two 6 m (20’) containers. Inspection of the containers substantiated each was packed with eight 1.265 m diameter (1.6 m high) rolls of newsprint, stacked four long and two wide. The centre of gravity for the wagon was calculated to be 1.38 m above the top of the rail. Examination of newsprint rolls within the containers established that it was unlikely that a load shift had occurred, and loading was within specification.

A review of TasRail records, established that, as part of a major refurbishment program, wagon TQMF03G had all primary springs replaced in May 2012, and the wagon was fully overhauled (including bogies) in July 2014. The wagon was serviced in accordance with TasRail's requirements and there were no outstanding maintenance issues.

Following the derailment, an inspection of TQMF03G included bogie frames, side-bearer assemblies, friction wedges, wheelsets and wheel profiles. All were found to be operationally fit for purpose, and in compliance with maintenance standards.

Train driver

The driver in control, at time of derailment, had worked for TasRail for about 45 years and had driven trains for the last 25 years. He held the required qualifications to drive trains on the TasRail network and was route certified for the track where the derailment occurred.

An examination of the driver’s records confirmed that he had been assessed as meeting the medical standards prescribed by the National Standard for Health Assessment of Rail Safety Workers. The ATSB examined the driver’s roster and determined that fatigue impairment was unlikely to have affected his performance. The driver said he felt well when signing on for duty and at the time of the derailment.

After the derailment, the driver underwent drug and alcohol testing, the results of which were negative.

Train Handling

Locomotives TR15 and TR13 were equipped with Wabtec event recorders (loco-log) and CCTV cameras. These systems were used for capturing information such as date/time, speed, brake pipe pressure, throttle position, distance travelled and video imagery. Analysis of the data (Figure 7) established:

• The train was travelling at about 33 km/h (7 km/h below maximum track speed) when the lead locomotive TR15 passed over the point of derailment (PoD).
• The speed of the train increased slightly, on a downgrade of 1:83, reaching 36 km/h (4 km/h below maximum track speed) as TQMF03G passed over the PoD. At the time of derailment, the train was in dynamic brake (DB).
• At 1925:25 the driver moved the throttle to idle (Idle) and then over the duration of about one minute, progressively increased the throttle to position T5 (in anticipation of a grade increase).
• At 1926:29 brake pipe pressure (BPP) began to reduce. At about the same time the driver increased the throttle position to T7, (to maintain speed) and then almost immediately reduced the throttle position to T2, then idle, realising the train may have derailed.
• The train slowed down, coming to a stop at 0926:39, about 2.6 km past the PoD.

Figure 7: Graph derived from Wabtec loco-log data, lead locomotive TR15

Source: TasRail, graphed by ATSB

A review of the loco-log data corroborates the driver’s recollection of events, and strongly indicates that train handling and driver performance were unlikely to have been factors that contributed to the derailment.

Examination of the track

The point of derailment (PoD) was identified at the 95.185 kps. The track leading into/out of the derailment site was found to be in fair condition. Both rails were good, with little evidence of side and top wear. There were no broken rails at or before the PoD. However, there did appear to be some geometry and condition irregularities leading up to the PoD. The ballast layer through the derailment site was shallow with evidence of pumping (vertical track movement) and there were signs of ballast fouling (fine materials, dirt/sand within the ballast layer).

Further examination of the track established signs of pre-existing damage to some steel sleepers. The damage was quite minor, probably related to dragging equipment, a previous derailment or similar event, and not considered a factor in this derailment. There was no evidence of track spread leading into or out of the derailment site. Gauge at the PoD was 1,069 mm; this was within TasRail tolerance (Refer Figure 11 – Response code/Tolerance, item re Track Gauge).

At the PoD there was evidence of flange climb,^[4] (direction of train travel) on the right side running rail, (high rail) followed by witness marks, over a distance of about 5 m, which is consistent with a wheel flange crossing over the railhead (Figure 8).

Figure 8: Witness marks at PoD (95.185 km) shown by line of arrows on railhead

 
Source: ATSB

Beyond the PoD, the leading wheelset of derailed wagon TQMF03G had dropped off the rails. It damaged the track structure both within the gauge side^[5] and on the field side^[6] of the track (direction of travel). Initially the damage was not significant.

When locomotives TR15 and TR13 travelled through the PoD, they were initially in dynamic brake (Figure 7). At that time, the trailing wagons were in buff (light compression), almost free rolling. When the locomotives were about 1.8 km from the PoD, the driver began to accelerate the train, for an upcoming grade increase. At that time, the wagons would have gone into draft (tension) and the derailed wagon (TQMF03G) pulled to the right, through the right hand curve, (96.5 kps) where it dropped off the ballast shoulder and rolled over.

This most likely caused the wagons ahead to roll over, and wagons behind to derail, resulting in the multi-wagon pile-up shown at Figure 3. Wagon TQMF03G had travelled about 2.3 km beyond the initial PoD before coming to rest.

While track damage was evident along the 2.3 km length of the line, there was no track damage at or before the PoD. The majority of track damage was about 2 km beyond the PoD. It is therefore most likely that any post incident survey measurements through the derailment site would reflect the condition of the track at the time of derailment. Any measured track defects probably existed prior to the passage of train 532.

Post-derailment track measurements

The post-derailment survey, undertaken by TasRail, measured a range of track parameters including track gauge, alignment, superelevation, twist and top. Figure 9 illustrates the geometry in terms of track twist^[7] – green line at 10 m intervals and the red line at 3 m intervals. The survey confirmed on-site visual observations that a series of geometry irregularities existed leading up to the point of derailment.

Figure 9: Twist measurements taken at derailment site (95.185 kps)

Source: TasRail – annotations ATSB

Track inspection and maintenance standards

The inspection and maintenance practices used by TasRail for its track and civil infrastructure are prescribed in the ‘Track and Structure Maintenance Standard’ (INF-TS-211 Ver 2.0 dated 26 August 2014).

The standard provides for two inspection routines: unscheduled and scheduled inspections. These routines adopt two main methods for assessing track geometry and identifying defects, visual inspections of track, and the use of mechanised track geometry vehicles.

Unscheduled

Unscheduled inspections are generally in response to defined events, such as extreme weather conditions known to increase the risk of geometry defects. Unscheduled inspections can also be triggered by third-party intervention, such as a train driver’s report of a rough riding track.

Scheduled

Scheduled inspections, in this case, for continuous steel sleeper track, (section length greater than 200 m) comprise:

• ‘on-track vehicle’ (weekly – No leeway, must complete inspection within 7 days, on or before last inspection date)
• ‘front of loco’ (3 monthly – leeway 2 months)
• ‘foot’ (for curves < 200 m, 18 monthly – leeway 2 months)
• ‘twist trolley’ (10 weekly – leeway 15 days) and
• ‘track geometry vehicle’ (annually, unless specified otherwise – leeway 30 days).

In accordance with the standard, track defects are grouped into one of three tolerance bands/codes, S, M or L, as defined in the table at Figure 10, ‘Track assessment response codes’.^[8]

Figure 10: Track assessment response codes

Source: TasRail: Track and Structure Maintenance Standard Table 5 (INF-TS-211 Ver 2.0 dated 26 August 2014)

The tolerance limits for each specific defect band/code, are as defined in the table at Figure 11, ‘TasRail Category B Lines where Track Segment Speeds are up to 70km/h’.

Figure 11: TasRail Category B Lines where Track Segment Speeds are up to 70km/h

Source: TasRail: Track and Structure Maintenance Standard (INF-TS-211 Ver 2.0 dated 26 August 2014)

The work priority (urgency) assigned against each specific code, S, M or L, is as prescribed in the table at Figure 12 ‘Inspection Guidelines, Prioritisation and Sub-Categorisation of Defects’.

Figure 12: Inspection Guidelines, Prioritisation and Sub-Categorisation of Defects

Source: TasRail: Track and Structure Maintenance Standard Table 6(INF-TS-211 Ver 2.0 dated 26 August 2014)

__________

4. A derailment in which a wheel flange will climb to the railhead.
5. The area between the two running rails.
6. The area on the ‘out sides’ of each of the running rails.
7. Twist is the variation in cross level over a defined distance, where cross level (cant) is the difference in level of the two rails at a single point along the track.
8. The requirements of a ‘Code L’ response were relaxed on 5 November 2014, vide Infrastructure Waiver 018, by deleting the wording ( REF _Ref460400736 \h Figure 10 – red strike through) ‘… for the passage of the first train/vehicle consist, only’. This modification to the standard allowed large defects, to be managed by way of an appropriate TSR.

Safety analysis

On 6 August 2015, TasRail intermodal freight train 532, travelling from Boyer to Burnie, derailed near Nala, Tasmania. The ATSB determined that the derailment was initiated by a track defect (twist irregularity), located just before the 95.185 km point south (kps). It was likely that the track defect induced significant body roll in wagon TQMF03G, and that the right wheel of the leading axle on the leading bogie was in an unloaded state when it contacted the running face of the right hand rail, resulting in flange climb, and subsequent derailment. Consequently, examination of track/rolling stock interaction and track inspection/maintenance operations became necessary to determine whether these areas were factors in the derailment.

Track inspection and maintenance

An extract of TasRail records (Figure 13) showed that scheduled inspections were regularly performed, and generally met or exceeded target dates. The last on-track vehicle inspection, highlighted in orange (Figure 13), was completed on schedule, three days before the derailment. A track defect was located just before the POD (95.130 kps) during that inspection, and resulted in the issue of a repair job advice on 4 August 2015, as highlighted in orange (Figure 14).

Figure 13: Scheduled track inspection history, period preceding derailment

Source: TasRail

Post-derailment analysis suggests that the geometry defects observed following the derailment of train 532 were probably consistent with the defects identified on 3 August 2015. Twist measurements taken post-derailment (Figure 9) showed the existence of a (10 m) twist defect 30 mm (medium) in size, followed by a (large) 36 mm defect, located 60 m and 40 m, respectively, before the PoD. Closer towards the POD were a series of smaller yet significant defects, with a 26 mm (medium) defect at the PoD. The magnitude and cyclic nature of these defects, in advance of the PoD, would have initiated significant body roll in wagons as they travelled through the derailment site.

TasRail maintenance standards prescribe that, for any twist defect greater than 30 mm, (10 m chord) it is mandatory to allocated a code L, and should be given a priority ‘1’ urgency response. Examination of the repair advice sheet (Figure 14) shows that the track inspector identified that spot tamping was required near the 95.130 kps, due to irregular top. The defect was not physically measured and was probably under estimated as a medium defect, M (>25 – 30mm). While the defect was identified as medium, (M) and would typically be allocated a priority 2 or 3 response, on this occasion it was allocated a priority 1 response, which was outside the instructions defined in TasRail’s maintenance standard INF-TS-211. A priority 1 response requires ‘Immediate attention is required’ under TasRail maintenance standard INF-TS-211 (Figure 12). The standard also clearly mandates that ‘No on-track vehicles can pass without the approval of District Track Manager or Track Manager Systems’. However, this response was not undertaken.

Figure 14: Extract from repair advice sheet dated 4 August 2015

Source: TasRail

An examination of other inspection and maintenance records found:

• A front of loco inspection was also completed on 3 August 2015, 3 days before the occurrence. There were no ride quality issues or defects reported, at or near the derailment site.
• A twist trolley inspection was completed on 18 June 2015, about 2 months before the occurrence. There were no repair advice notifications or identified issues at or near the derailment site. However, it was noted that the report did not include a category for 10 m twist defects.
• The track through the site was examined using a mechanised track geometry inspection car on 5 May 2015, about 3 months before the derailment.

Figure 15 (top portion) is a graphical extract of that track geometry car report of 5 May 2015. It shows a series of twist irregularities before the 95.185 kps location. The largest was a 32 mm twist defect at the 95.179 kps, close to the POD. The twist defect was categorised as a priority 1 defect and recorded in an exceedance report (Figure 15 – bottom portion). TasRail’s maintenance records show no evidence of any corrective action in response to this priority 1 defect.

Subsequent advice by TasRail stated that:

This defect was also not considered a priority in the context of the overall volume of identified defects. Consequently these defects were not scoped and/or repaired prior to 06 August 2015.

This statement, and maintenance action following the identification of a priority 1 defect three days before the derailment, suggests that TasRail did not enforce documented maintenance standards, which required immediate attention and exclusion of vehicles until approval was given by the track manager.

Figure 15: Extract of track geometry car, report of 5 May 2015 near PoD (95.185 kps)

Source: TasRail – annotations ATSB

Track history

An extract of TasRail’s maintenance records (Figure 16) established that there were at least five instances of track geometry/stability issues, (not including the track geometry car inspection of 5 May 2015 and on-track vehicle inspection of 3 August 2015) at or near the PoD requiring maintenance intervention since 2008.

Figure 16: Extract of maintenance records Campania to Conara Junction (near derailment site)

Source: TasRail

TasRail acknowledged that the formation was generally in poor condition through the area. A 100 mm ballast layer over fouled ballast was considered typical. TasRail also identified at least two locations just before the POD that showed evidence of track pumping. This suggested the possibility of voids under the track that may have contributed to track geometry irregularities as vehicles passed through the area.

The track structure through the derailment site adopted the use of steel sleepers. While steel sleepers provide good gauge holding, they demand considerable maintenance effort to manage track stability/alignment. A study in NSW^[9] found that steel sleepers need to have correct installation as they do not perform well in situations where the track structure (ballast and formation) is poor. The report highlighted that correct tamping is essential to ensure the insertion of the ballast into the underside of the steel sleeper. Any lack of ballast under the sleeper void is difficult to observe visually and may reduce the structural stability of the track, especially in tight curves.

In this case, steel sleepers had been installed, the track contained a series of tight curves and the structure was known to be in relatively poor condition with fouled ballast. The repetitive nature of track geometry defects identified through track inspections also suggests the area was prone to track stability issues. TasRail’s track and maintenance (INF-TS-211 at section 3.8.1, general item 8) states that track sections prone to stability failure should be identified and managed as hazardous locations. There was no record of the track near the 95.5 kps having been identified as a hazardous location, so it had not attracted greater analysis focus or maintenance attention.

Other occurrences involving track twist irregularities

The ATSB has previously investigated two derailments in Tasmania involving track twist irregularities involving train 331 near Lowdina, on 9 April 2013 (RO-2013-012), and train 135 near Kimberley on 25 January 2015 (RO-2015-001).

Track geometry was identified as the underlying factor in these derailments including the derailment of train 532 on 6 August 2015. All three derailments occurred on steel sleeper track through areas having tight curves, and involved older rolling stock exhibiting less tolerant dynamic performance.

Rolling stock

To assist in understanding the mechanism of derailment, and help in developing strategies to mitigate the risk of future derailment, TasRail engaged consultants to model the dynamic performance of the older TQMF class of wagon (type that derailed) and TQAY wagons, using the Vampire computer simulation package. The track criterion incorporated into the simulation model was based on survey work undertaken post-derailment. The dynamic performance of the wagons was modelled for varying characteristics and a range of speeds, including the derailment speed of 36 km/h.

The computer modelling clearly showed that the older generation TQMF, when compared to the newer TQAY wagons, were much more susceptible to derailment over the track defect at the 95.185 kps. Modelling suggested that the newer generation TQAY wagons were able to negotiate the same track defect without derailing.

At the critical speed of 36 km/h, the modelling established that the TQMF wagons derailed when traversing the track irregularity. This speed gave rise to the highest wheel unloading at a time when the wheel came into contact with the rail face at the 95.185 kps, resulting in flange climb and subsequent derailment.

It is likely that cyclic body roll due to a series of track irregularities caused the right-hand wheel on the lead axle on the leading bogie (TQMF03G) to lift. At the same time, the process of negotiating a left-hand curve placed that wheel in contact with the right-hand rail running, resulting in flange climb of the lightly loaded wheel and subsequent derailment. Although it was determined that TQMF03G was in good condition, the suspension characteristics of this wagon type, compared to the newer TQAY wagons, were probably key factors that contributed to the derailment.

The results of the computer modelling were used by TasRail to identify a number of strategies that could be used to enhance the dynamic performance of the TQMF wagon and reduce the risk of future derailments, including the use of constant-contact side-bearers.^[10] TasRail proposes to adopt the recommendations of the report.

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9. Steel Sleeper Introduction on NSW Class 1 Main Line Track.1996 - 2004 (OTSI - File Ref: 02619)
10. In freight wagons that use three-piece bogies, there is a tendency for the wagon to rock from side to side on the 'centre-plate' to 'centre bowl' connection. To limit the rocking motion of the wagon body, 'side-bearers' are fitted to the bolster. There are variations in the design of side-bearers, and constant-contact side-bearers are used in the more modern designs. Constant-contact side-bearers also provide additional resistance to rotation of the bogie, which improves stability but reduces curving performance.Design and Simulation of Rail Vehicles By Maksym Spiryagin, Colin Cole, Yan Quan Sun, Mitchell McClanachan, Valentyn Spiryagin, Tim McSweeney

Safety actions

Whether or not the ATSB identifies safety issues in the course of an investigation, relevant organisations may proactively initiate safety actions in order to reduce their safety risk. The ATSB has been advised of the following proactive safety actions in response to this occurrence.

Additional safety action taken by TasRail

TasRail has advised of the following proactive safety actions:

• Computer modelling by Worley Parsons to identify any additional criteria that could be used to interpret geometry measures to identify situations where a combination of defects could contribute to a heightened derailment risk.
• Update the TasRail Operational Risk Register V5 when outcome of modelling known - Hazard 2 - Train Derailment.
• Track Maintenance Standard INF-TS-211 has been updated (Version 3) on 04 April 2016 with respect to various operational and maintenance procedures, including:

- Removes the requirement to obtain track manager permission to travel over large faults and introduces geometry defect thresholds at which TSRs shall be applied enabling consistent management by the track inspector.

- Removes hazardous locations and introduces unstable twist defects which are locations that must be measured by inspectors during every patrol to mandate more rigorous monitoring of areas that rapidly deteriorate.

- Has been updated to include a revised repair advice sheet which now requires that measurements be taken for all reported geometry defects.

- Includes specific actions to be taken for each defect size

• Geismar digital track geometry trolleys issued to all track inspectors to enable accurate sizing of defects.
• Track geometry vehicle now operated six weekly on busiest lines (South and Western).
• TasRail has committed to invest in its own, vehicle mounted, track geometry measuring equipment enabling more frequent and accurate track monitoring
• Update Infrastructure Derailment Form INF-FRM-019 to include the measurement of voiding following incident investigation.
• Fitting of ‘Constant Contact Side Bearers’ on the fleet of TQMF and IB wagons.
• Update standard RS-TS-006 to include side-bearer gaps clearances.
• Inspect TQMF wagons side-bearer gaps and friction wedges to ensure all are within specification.
• Update 'A' service sheet RS-FRM-242 to include inspection of side-bearer gap clearances measurements.
• Update wagon work instruction RS-Wl-531 to include correct service limits and measurement criteria.

Findings

On 6 August 2015, TasRail intermodal freight train 532, travelling from Boyer (near Hobart) to Burnie derailed on a section of track near Nala, Tasmania.

From the evidence available, the following findings are made with respect to the derailment and should not be read as apportioning blame or liability to any particular organisation or individual.

Contributing factors

• The derailment of train 532 was probably initiated by a track defect (twist irregularity), just before the 95.185 km point south (kps).
• The wagon (TQMF03G) suspension characteristics, loading, critical train speed, (36 km/h), and nature of the track defect, were factors that contributed to the derailment.
• A track defect was identified three days before the derailment, categorised as priority 1 requiring immediate attention, but did not result in a maintenance response as specified in TasRail’s maintenance standard INF-TS-211.

Other factors that increased risk

• TasRail maintenance standard INF-TS-211 does not provide guidelines for the determination of track defect size.
• There were no documents that could establish whether the track inspector met mandated reporting requirements, (specified within TasRail’s maintenance standard INF-TS-211) where on-track vehicles are not permitted to pass a priority 1 defect, without approval of the track manager.
• TasRail records showed a history of track geometry defects near the derailment site, but monitoring strategies did not alert maintenance staff to the possible need for higher vigilance through this area.
• The track stability problems near the derailment site were probably a reflection of poor track formation, ballast quality and the use of steel sleepers, in particular the packing of ballast under the sleeper and at the sleeper ends.

Other findings

• Train handling and driver performance were not factors that contributed to the derailment.
• Environmental conditions were not factors that contributed to the derailment.

The occurrence

At about 1554^[1] on 6 August 2015, TasRail intermodal freight train 532, (carrying rolls of newsprint and empty containers), departed Boyer in southern Tasmania (Figure 1) for Burnie in the north. The driver (driver only operation) involved in the occurrence booked on for duty, earlier that day (1430) at the East Tamar depot, Launceston. He then drove by car, to Campania where a crew change occurred at 1710. Train 532 departed shortly thereafter, the driver having obtained authority to work through to Parattah.

Figure 1: Location map – TasRail network

Source: NatMap, Geoscience Australia

The passage of the train through to Colebrook, about 30 km south of Nala, was uneventful. Shortly after departing Colebrook, the driver experienced degraded train performance and needed to stop on several occasions to rectify a fault^[2]. At about 1841, the driver cleared the fault and then proceeded towards Parattah.

At 1856, the driver received authority to work through to Conara Junction. The train subsequently passed through Parattah, (about 9 km south of Nala) at 1911. At about 1921, the train passed over the Inglewood Road railway crossing (Figure 2) before entering a sweeping left curve (170 m radius). Just after passing, the 95 km point south, (kps)^[3] the train traversed a short straight section of track, and then crossed over the Inglewood rail over-road bridge. The train continued to snake its way north towards Nala.

As the train approached the Nala Road railway crossing, the driver advanced the throttle to maintain speed. However, the train slowed, so the driver opened the train window, looked back towards the rear of the train, and saw sparks part way along the train. At about the same time as the train brakes began to apply automatically, the driver throttled off to reduce power. The lead locomotive TR15 stopped about 120 m past the Nala Road railway crossing.

Figure 2: Derailment site near Nala

Source: Google Earth

Post occurrence

The driver contacted train control to advise that the train had come to a stand just past the Nala Road railway crossing and had probably derailed. After speaking to train control and activating his personal alarm monitor, he detrained and walked the length of the train to inspect for damage. On completing the inspection, he returned to the cab and communicated with train control, advising that a number of wagons had derailed and that there was extensive track damage (Figure 3).

Figure 3: Rear part of train 532 adjacent 97.5 km post

Source: ATSB

At about 1930, train control called the incident co-ordinator. Operations staff, investigation and recovery crews were then dispatched to site.

The line was re-opened to rail traffic at about 0200 on 9 August 2015, three days after the occurrence.

__________

1. The 24-hour clock is used in this report and is referenced from Eastern Standard Time (EST).
2. The fault was related to the communication of data between the locomotives.
3. Measured from Hobart on the South Line.

Purpose of safety investigations & publishing information

Purpose of safety investigations The objective of a safety investigation is to enhance transport safety. This is done through: identifying safety issues and facilitating safety action to address those issues providing information about occurrences and their associated safety factors to facilitate learning within the transport industry. It is not a function of the ATSB to apportion blame or provide a means for determining liability. At the same time, an investigation report must include factual material of sufficient weight to support the analysis and findings. At all times the ATSB endeavours to balance the use of material that could imply adverse comment with the need to properly explain what happened, and why, in a fair and unbiased manner. The ATSB does not investigate for the purpose of taking administrative, regulatory or criminal action. Terminology An explanation of terminology used in ATSB investigation reports is available here. This includes terms such as occurrence, contributing factor, other factor that increased risk, and safety issue. Publishing information  Released in accordance with section 25 of the Transport Safety Investigation Act 2003 Published by: Australian Transport Safety Bureau © Commonwealth of Australia 2017 Ownership of intellectual property rights in this publication Unless otherwise noted, copyright (and any other intellectual property rights, if any) in this report publication is owned by the Commonwealth of Australia. Creative Commons licence With the exception of the Coat of Arms, ATSB logo, and photos and graphics in which a third party holds copyright, this publication is licensed under a Creative Commons Attribution 3.0 Australia licence. Creative Commons Attribution 3.0 Australia Licence is a standard form licence agreement that allows you to copy, distribute, transmit and adapt this publication provided that you attribute the work. The ATSB’s preference is that you attribute this publication (and any material sourced from it) using the following wording: Source: Australian Transport Safety Bureau Copyright in material obtained from other agencies, private individuals or organisations, belongs to those agencies, individuals or organisations. Where you wish to use their material, you will need to contact them directly.

What happened

On 6 August 2015, the pilot of a Grumman G164 aircraft, registered VH-LKN, was conducting aerial spreading of superphosphate on a property about 33 km south-west of Tharwa, Australian Capital Territory. The target zone for the spreading was about 7 km to the south-east, and at an elevation about 1,000 ft higher than the airstrip and loading site.

The pilot commenced operations at about 1000 Eastern Standard Time (EST) and completed spreading of six loads of superphosphate. The pilot then had a lunch break and refuelled the aircraft to a total of about 180 L of fuel. The aircraft was also loaded with about 500 kg of superphosphate, which was about half its carrying capacity. The pilot observed a light, westerly wind of about 2 to 5 kt in the vicinity of the airstrip.

At about 1400, the pilot commenced the take-off run for the seventh load of the day. As the aircraft became airborne, the aircraft started to sink (Figure 1). To stop the aircraft sinking, the pilot applied the dump lever to start dumping the load of superphosphate. The aircraft then started to climb, so the pilot stopped dumping the load. The pilot also commenced a shallow left turn, away from rising terrain. As the aircraft turned, when at about 100 ft above ground level, it started to sink again. As it sank, the pilot felt a shake through the airframe, indicating that the aircraft was close to stalling. The pilot re-applied the dump lever to open the hopper door and try to reduce the aircraft load. Simultaneously, the pilot lowered the aircraft’s nose and rolled the wings level, to try to recover from the incipient stall.

Figure 1: Departure airstrip, aircraft track and accident location

Source: Google earth and pilot recollection – annotated by the ATSB

The pilot sighted powerlines, a road and a row of trees ahead, beyond which the terrain rose steeply. The aircraft continued to descend and the pilot maintained the aircraft in a normal nose attitude for landing. As the aircraft neared the ground, the pilot reduced the throttle to idle and held the aircraft control stick in the full back position. The tailwheel struck the ground first, and then the right main landing gear dug into soft ground. The aircraft flipped over and came to rest inverted.

The pilot sustained minor injuries and the aircraft was substantially damaged (Figure 2).

Figure 2: Damage to VH-LKN

Source: Pilot

Pilot comments

The pilot provided the following comments:

• The airstrip was at an elevation of about 2,100 ft above mean sea level. The target pasture was about 1,000 ft higher than the airstrip.
• The airstrip was about 500 m in length and the fuel and chemical load was relatively light. The aircraft was well within its operational limitations.
• The weather forecast had indicated calm conditions, and the temperature was about 14°C.
• The sink that the aircraft encountered may have been a downdraft coming off the hill.
• If the airstrip had been higher up and closer to the target zone, the pilot would have had more time to dump the load, less distance to climb on each load, and a more accurate assessment of the wind conditions.
• Dumping liquid takes a few seconds, but granular substances like superphosphate take minutes for the hopper to empty when dumping the load.
• After the accident, the pilot verified that the hopper door was open, and superphosphate was present in the paddock, indicating that it had been dumping at the highest rate. Despite that, about 300 kg of superphosphate remained in the hopper.

Safety message

The pilot stated that the key to avoiding similar incidents was to understand the atmospheric conditions in steep mountainous country. Variations in wind strength and direction due to terrain can have serious consequences on flight safety, particularly when operating at low airspeeds and close to the ground.

ATSB investigated a similar accident involving a Grumman G-164A, in AO-2014-001.

Aviation Short Investigations Bulletin Issue 44

Purpose of safety investigations The objective of a safety investigation is to enhance transport safety. This is done through: identifying safety issues and facilitating safety action to address those issues providing information about occurrences and their associated safety factors to facilitate learning within the transport industry. It is not a function of the ATSB to apportion blame or provide a means for determining liability. At the same time, an investigation report must include factual material of sufficient weight to support the analysis and findings. At all times the ATSB endeavours to balance the use of material that could imply adverse comment with the need to properly explain what happened, and why, in a fair and unbiased manner. The ATSB does not investigate for the purpose of taking administrative, regulatory or criminal action. Terminology An explanation of terminology used in ATSB investigation reports is available here. This includes terms such as occurrence, contributing factor, other factor that increased risk, and safety issue. Publishing information  Released in accordance with section 25 of the Transport Safety Investigation Act 2003 Published by: Australian Transport Safety Bureau © Commonwealth of Australia 2015 Ownership of intellectual property rights in this publication Unless otherwise noted, copyright (and any other intellectual property rights, if any) in this report publication is owned by the Commonwealth of Australia. Creative Commons licence With the exception of the Coat of Arms, ATSB logo, and photos and graphics in which a third party holds copyright, this publication is licensed under a Creative Commons Attribution 3.0 Australia licence. Creative Commons Attribution 3.0 Australia Licence is a standard form licence agreement that allows you to copy, distribute, transmit and adapt this publication provided that you attribute the work. The ATSB’s preference is that you attribute this publication (and any material sourced from it) using the following wording: Source: Australian Transport Safety Bureau Copyright in material obtained from other agencies, private individuals or organisations, belongs to those agencies, individuals or organisations. Where you wish to use their material, you will need to contact them directly.

What happened

On 20 July 2015, the pilot of a Bell 206L3 (Longranger) helicopter, registered VH-BLV (BLV), conducted a charter flight from Essendon Airport to Falls Creek, Victoria, with five passengers on board. The aircraft took off from Essendon close to its maximum take-off weight. Due to the weight, and therefore fuel limitations, the pilot landed and refuelled at a property near Lake Eildon. At about 1000 Eastern Standard Time (EST), the helicopter departed from the property for the 60 NM flight to Falls Creek, again close to its maximum take-off weight.

At about 1030, while 700 ft above ground level and tracking from the north-west, the pilot conducted a shallow approach towards the helipad at Falls Creek (Figure 1). As the helicopter descended to about 50 ft above ground level, the pilot found that significantly more power was required to conduct the approach than anticipated. The pilot assessed that there was insufficient power available to continue to land, and elected to abort the approach. The pilot pushed forwards on the cyclic^[1] to increase the helicopter’s airspeed and conducted a left turn towards the valley.

Figure 1: Falls Creek helipad, approximate helicopter track and wind direction

Source: Google earth and pilot recollection – annotated by the ATSB

As the helicopter turned left, it started to yaw^[2] rapidly towards the right. The pilot applied full left pedal to counteract the yaw, but the helicopter continued to yaw. The helicopter turned through one and a half revolutions, as the pilot lowered the collective.^[3] Lowering the collective reduced the power demand of the power rotor system, thereby increasing the ability of the anti-torque pedals to stop the right yaw. The combination of lowering collective and applying forward cyclic to gain forward airspeed, allowed the pilot to regain control of the helicopter. The pilot then conducted a left turn towards the helipad and made an approach to the helipad from an easterly direction. The helicopter landed following the second approach without further incident.

The pilot and passengers did not sustain any injuries and the helicopter was undamaged.

Weather

The pilot expected that the wind at Falls Creek would be variable at 2 kt, as it had been on departure from Essendon. The pilot did not see the windsock at the helipad prior to conducting the approach.

The Bureau of Meteorology provided the ATSB with a report of weather observations for Falls Creek. The automatic weather station is located south of the helipad at about 5,790 ft above mean sea level, above the village. Between 1020 and 1040, the recorded wind speed was from 17 to 20 kt, gusting to 24 kt, and wind direction was from 327° to 344° (degrees true), or 314° to 331° (degrees magnetic). The temperature was 1 °C.

Pilot comments

The pilot reported that the following combination of factors contributed to the incident:

• Unfamiliarity with the landing site and area.
• Inexperience operating at altitude, and unfamiliarity with the associated power requirements. The helipad at Falls Creek is at an elevation of about 5,000 ft above mean sea level.
• Lack of experience in the aircraft type – although the pilot had about 60 hours experience in the Bell Jetranger, this was only the pilot’s second flight in the Longranger.
• High all up weight.
• Incorrect assessment of the wind direction – the pilot assumed that the wind would be light and variable at Falls Creek as it was had been on departure from Essendon. During the approach, the pilot assessed that the wind was from the right or a tailwind gusting to about 15 kt.

Operator comment

The operator of VH-BLV assessed that the unanticipated yaw was a result of too little pedal input, applied too late. This was most likely due to a combination of the pilot’s inexperience on the 206L3, and being surprised by the downwind approach.

Hover ceiling

Hovering requires more power than any other flight regime. Additionally, hovering at higher altitudes requires more power than to hover at lower altitudes. The ‘hover ceiling’ is the height at which the power available equals the power required to hover. An increase in power increases the main rotor torque. This additional torque needs increased tail rotor thrust, to prevent the helicopter from yawing.

The Bell 206 L3 flight manual provides a Hover ceiling – out of ground effect^[4] chart. At 5,000 ft, a temperature of 0 °C, and a gross weight of about 1,814 kg (4,000 lb), the helicopter was just within the chart’s hover ceiling envelope. This indicates that adequate power should have been available to hover with those parameters. However, the wind direction and velocity also affect hovering performance.

A stronger head wind reduces the power required to hover, while a tailwind increases the power required to hover. On the initial approach to the helipad, a tailwind meant that an increase in power and tail rotor thrust was required. The increased tail rotor thrust absorbs power from the engine, which means less power is available for the main rotor to produce lift. This led to the pilot’s assessment of insufficient power available, and decision to discontinue the approach.

Unanticipated right yaw

The US Federal Aviation Administration (FAA) Helicopter flying handbook describes loss of tail rotor effectiveness (LTE) or an unanticipated yaw, as ‘an uncommanded, rapid yaw towards the advancing blade which does not subside of its own accord’. It is caused by an interaction between the main rotor and tail rotor.

At high altitudes, the lower air density reduces tail rotor thrust and efficiency. Therefore, when operating at high altitudes and high gross weights, particularly while hovering or at low airspeeds, the tail rotor thrust may not be sufficient to maintain directional control. This can result in unanticipated yaw or LTE. In these circumstances, the hover ceiling is effectively limited by the tail rotor thrust, rather than the power available.

In this incident, other factors may also have contributed to the unanticipated yaw: low and slow flight outside of ground effect, a low speed downwind turn and a large change of power at low airspeed as the pilot aborted the approach.

The US Federal Aviation Administration Advisory Circular, Unanticipated right yaw in helicopters, stated that unanticipated right yaw, or loss of tail rotor effectiveness (LTE) has been determined to be a contributing factor in a number of accidents. These mishaps have occurred at low altitude and in low-speed flight, often on final approach to landing. Unanticipated right yaw may occur during any manoeuvre in which the pilot is operating in a high-power, low-airspeed environment with a left crosswind (in aircraft with counter-clockwise blade rotation) or tailwind.

Three additional factors can significantly influence the severity of LTE:

• gross weight and density altitude
• low indicated airspeed
• a rapid application of power, causing power droop.

In order to reduce the onset of LTE, when manoeuvring between hover and 30 kt, the pilot should:

• Avoid tailwinds.
• Avoid out of ground effect hover and high-power demand situations, such as low-speed downwind turns.
• Be aware of wind direction and velocity. A loss of translational lift results in an unexpected high-power demand and an increased anti-torque requirement.
• Be aware that if a considerable amount of left pedal is being maintained, a sufficient amount of left pedal may not be available to counteract an unanticipated right yaw.
• Stay vigilant to power and wind conditions.

If a sudden unanticipated right yaw occurs, the pilot should:

• apply full left pedal
• simultaneously move cyclic forward to increase speed
• if altitude permits, reduce power.

Safety message

Pilots should understand and avoid conditions that are conducive to uncontrolled yaw or loss of tail rotor effectiveness. Pilots can reduce their exposure to LTE by maintaining awareness of the wind and its effect on the helicopter. If a pilot encounters unanticipated yaw, quick application of the correct response is essential to recover control of the helicopter. The ATSB reported on an incident involving LTE in AO-2013-121.

This incident also highlights the effect of gross weight and airfield elevation on aircraft performance. Understanding controllability issues at the limits of the normal operating envelope can assist pilots in recognising the symptoms of reduced aircraft performance. Further information is available in ATSB report AO-2013-203.

Aviation Short Investigations Bulletin Issue 44

Purpose of safety investigations The objective of a safety investigation is to enhance transport safety. This is done through: identifying safety issues and facilitating safety action to address those issues providing information about occurrences and their associated safety factors to facilitate learning within the transport industry. It is not a function of the ATSB to apportion blame or provide a means for determining liability. At the same time, an investigation report must include factual material of sufficient weight to support the analysis and findings. At all times the ATSB endeavours to balance the use of material that could imply adverse comment with the need to properly explain what happened, and why, in a fair and unbiased manner. The ATSB does not investigate for the purpose of taking administrative, regulatory or criminal action. Terminology An explanation of terminology used in ATSB investigation reports is available here. This includes terms such as occurrence, contributing factor, other factor that increased risk, and safety issue. Publishing information  Released in accordance with section 25 of the Transport Safety Investigation Act 2003 Published by: Australian Transport Safety Bureau © Commonwealth of Australia 2015 Ownership of intellectual property rights in this publication Unless otherwise noted, copyright (and any other intellectual property rights, if any) in this report publication is owned by the Commonwealth of Australia. Creative Commons licence With the exception of the Coat of Arms, ATSB logo, and photos and graphics in which a third party holds copyright, this publication is licensed under a Creative Commons Attribution 3.0 Australia licence. Creative Commons Attribution 3.0 Australia Licence is a standard form licence agreement that allows you to copy, distribute, transmit and adapt this publication provided that you attribute the work. The ATSB’s preference is that you attribute this publication (and any material sourced from it) using the following wording: Source: Australian Transport Safety Bureau Copyright in material obtained from other agencies, private individuals or organisations, belongs to those agencies, individuals or organisations. Where you wish to use their material, you will need to contact them directly.

__________

1. A primary helicopter flight control that is similar to an aircraft control column. Cyclic input tilts the main rotor disc varying the attitude of the helicopter and hence the lateral direction.
2. Term used to describe motion of an aircraft about its vertical or normal axis.
3. A primary helicopter flight control that simultaneously affects the pitch of all blades of a lifting rotor. Collective input is the main control for vertical velocity.
4. Helicopters require more power to hover out of ground effect due to the absence of a cushioning effect created by the main rotor downwash striking the ground. The distance is usually defined as more than one main rotor diameter above the surface.

 

What happened

On 1 August 2015, at about 1110 Western Standard Time (WST), a Cessna 210 aircraft, registered VH-ERU, departed Gidgee Gold mine for a private flight to Cue, Western Australia (Figure 1). The pilot was the sole occupant of the aircraft. The pilot reported that all engine indications were normal from the start and into the cruise at 3,500 ft above mean sea level. The elevation of the terrain in the area was about 1,700 ft above mean sea level.

Figure 1: Aircraft track and accident location

Source: Google earth – annotated by the ATSB

About 25 minutes into the flight, the pilot observed the engine oil temperature rising rapidly. The pilot opened the cowl flaps in an attempt to reduce the engine oil temperature, and noted that the cylinder head temperature and engine oil pressure were still in the normal range. As the pilot tried to determine the cause of the problem, the manifold pressure started to increase. The pilot reduced the throttle to try to decrease the manifold pressure, but it continued to rise.

The pilot then felt a slight vibration in the engine and through the aircraft controls, and broadcast a PAN^[1] call on the Melbourne Centre radio frequency. The pilot did not receive any response to the broadcast, probably due to the aircraft’s remoteness and low altitude. The aircraft was descending steadily, and the pilot looked for a suitable place to conduct a precautionary landing. However, the surrounding area was heavily treed. After turning towards the north and more open country, the vibration increased, and the pilot broadcast two Mayday^[2] calls. Again, the pilot did not receive any response.

When about 500 ft above ground level, the vibration further increased and the engine failed with a bang. Smoke emanated from the engine compartment and over the windscreen, reducing the pilot’s visibility through it. The pilot then sighted a fence line to the right and prepared for a forced landing, aiming to touchdown in a cleared area alongside the fence.

The pilot lowered the landing gear and extended the flap. When at about treetop height, the pilot selected the master switch and fuel off. The pilot also tightened the seatbelt and opened the aircraft door. As the pilot flared the aircraft to land, the right wing and strut collided with a tree. The aircraft yawed to the right, and the right main landing gear struck the ground and broke off. Although the pilot applied full left rudder to try to regain control of the aircraft, it collided with another tree and rolled onto its left side, before skidding and coming to rest against a third tree. The pilot suffered minor injuries and the aircraft sustained substantial damage (Figure 2).

The right fuel line ruptured during the impact sequence, causing fuel to run down into the cabin and onto the pilot. The pilot quickly exited the aircraft, concerned about the risk of fire, particularly as there was about 240 L of fuel in the tanks.

After waiting about half an hour for the fuel to stop running into the cockpit, the pilot returned to the aircraft and selected the master switch on. The pilot then made another radio broadcast requesting assistance, and again did not receive any response. The aircraft’s emergency locator transmitter (ELT)^[3] did not activate on impact, and its light had not illuminated. The pilot then tried, without success, to use the aircraft battery to power the ELT.

At about 1400, the pilot again made radio broadcasts without any response. As there was no mobile phone signal at the accident site, the pilot started walking towards higher terrain. At about 2200, after walking 25 km, the pilot gained mobile phone coverage and was able to call for assistance. After making the call, the pilot lit a fire to provide warmth and to deter a pack of wild dogs that had been circling. At about 0200 on 2 August, low cloud rolled in and it started to drizzle. About an hour later, the pilot provided rescue personnel with the coordinates of the location, obtained from the mobile phone. At about 0730, a rescue aircraft located the pilot and police arrived about 40 minutes later.

Figure 2: Accident site showing damage to VH-ERU

Source: Western Australia Police

Pilot comments

The pilot provided the following comments:

• The number three cylinder failed and blew a hole in the top of the engine casing.
• The pilot usually carried a satellite phone, but did not have it on this flight as it was being serviced.
• It was about a 40-minute flight to Cue, and the pilot would normally have advised someone of the planned route and expected arrival time, but omitted to do so on this day.
• The pilot had water, a first aid kit and a lighter in the aircraft, and planned to get a personal location beacon to carry in future.

Aircraft engine

The aircraft was fitted with a Continental IO-520 engine. The pilot had owned the aircraft for about 4 years, during which time the aircraft had accrued about 60 hours of flying time. Shortly after the pilot bought the aircraft, the number three cylinder had failed and been replaced. The pilot had recently replaced the propeller in accordance with an airworthiness directive.

The aircraft was damaged beyond repair. At the time of completing this report, no engineering inspection of the engine had been, or was expected to be, conducted following the accident.

Safety message

The ATSB reminds all pilots to let someone know where they are going, and what time they expect to arrive, before embarking on a flight. Although the incident flight was not in a designated remote area, it demonstrates that it is vitally important to carry emergency supplies, such as water, food, matches (or lighter), and first aid essentials. Where mobile and radio coverage is not available, a satellite phone can provide life-saving access to help.

Electronic locator transmitters installed in aircraft should be tested in accordance with the manufacturer’s instructions. The ATSB research report AR-2012-128 found that ELTs function as intended in about 40-60% of accidents. NASA is currently conducting

to find ways to make ELTs more likely to function after a survivable crash.

Aviation Short Investigations Bulletin Issue 44

Purpose of safety investigations The objective of a safety investigation is to enhance transport safety. This is done through: identifying safety issues and facilitating safety action to address those issues providing information about occurrences and their associated safety factors to facilitate learning within the transport industry. It is not a function of the ATSB to apportion blame or provide a means for determining liability. At the same time, an investigation report must include factual material of sufficient weight to support the analysis and findings. At all times the ATSB endeavours to balance the use of material that could imply adverse comment with the need to properly explain what happened, and why, in a fair and unbiased manner. The ATSB does not investigate for the purpose of taking administrative, regulatory or criminal action. Terminology An explanation of terminology used in ATSB investigation reports is available here. This includes terms such as occurrence, contributing factor, other factor that increased risk, and safety issue. Publishing information  Released in accordance with section 25 of the Transport Safety Investigation Act 2003 Published by: Australian Transport Safety Bureau © Commonwealth of Australia 2015 Ownership of intellectual property rights in this publication Unless otherwise noted, copyright (and any other intellectual property rights, if any) in this report publication is owned by the Commonwealth of Australia. Creative Commons licence With the exception of the Coat of Arms, ATSB logo, and photos and graphics in which a third party holds copyright, this publication is licensed under a Creative Commons Attribution 3.0 Australia licence. Creative Commons Attribution 3.0 Australia Licence is a standard form licence agreement that allows you to copy, distribute, transmit and adapt this publication provided that you attribute the work. The ATSB’s preference is that you attribute this publication (and any material sourced from it) using the following wording: Source: Australian Transport Safety Bureau Copyright in material obtained from other agencies, private individuals or organisations, belongs to those agencies, individuals or organisations. Where you wish to use their material, you will need to contact them directly.

__________

1. An internationally recognised radio call announcing an urgency condition which concerns the safety of an aircraft or its occupants but where the flight crew does not require immediate assistance.
2. Mayday is an internationally recognised radio call for urgent assistance.
3. Crash-activated radio beacon that transmits an emergency signal that may include the position of a crashed aircraft. Also able to be manually activated.

 

What happened

On 23 July 2015, an Airbus A330 aircraft, registered VH-QPJ and operated by Qantas Airways, was being loaded at Bangkok Airport, Thailand, prior to flying to Sydney, Australia. The ground-handling agent (and loading supervisor) was in Bangkok, and the load controller was in Warsaw, Poland.

The load instruction report (LIR) displayed a pictorial representation of the planned uplift. To maximise uplift within the aircraft’s operational limitations, the report contained a set of loading instructions. These instructions identify positions within the aircraft hold for loading containers, baggage and freight.

The load controller in Warsaw issued a load instruction report (LIR) to the loading supervisor in Bangkok (Figure 1). The loading supervisor was required to load the aircraft in accordance with the LIR. The LIR also contained ‘Special instructions’ and ‘Special load details’. The Special instructions for QF24 stated that the freight pallet shown on the LIR in position 23P was on standby. The loading supervisor then called the load controller by telephone to provide a ‘partial read back’. The supervisor read back to the controller how the aircraft had been loaded, based on the LIR.

The loading supervisor commenced by reading out the description and weight of the pallet loaded into position 23P. The load controller responded that the pallet in 23P was on standby as per the Special instructions, and directed the loading supervisor to offload that freight. The supervisor responded ‘yes’, and stated that the loading was in accordance with the LIR. The loading supervisor then continued to read the loading to the controller, again commencing with the pallet in 23P, followed by the rest of the loaded freight. The pallet in 23P remained loaded on the aircraft.

Figure 1: Load instruction report showing freight positions and special instructions

Source: Aircraft operator

After completion of the loading, the loading supervisor again phoned the load controller to provide the final read back of the loading. The loading supervisor stated ‘forward compartment no change’, to which the load controller responded clarifying position 23P was ‘no fit’^[1]. The loading supervisor replied, ‘yeah, no change’ and the load controller responded ‘ok’.

The load controller then prepared the final load sheet for the flight, based on the information provided over the phone by the loading supervisor. The load controller transmitted the final load sheet to the flight crew via the Aircraft Communications Addressing and Reporting System (ACARS). The load sheet included the calculated aircraft total and component weights including fuel, passenger, baggage and freight weights. It also provided the aircraft balance details including the aircraft take-off trim setting position.

The flight crew then used this data to calculate reference speeds for take-off, fuel consumption rates, and initial climb altitude. At about midday local time, the aircraft departed Bangkok for Sydney and the flight crew did not detect any abnormal flight characteristics, nor did they receive any warnings related to the aircraft’s weight or balance.

After the flight had closed, the load control system automatically generated a Container Pallet Message (CPM) report. The report was based on the input from the load controller, and therefore did not include the pallet in 23P. The loading supervisor identified that the pallet in 23P was not on this report and contacted the load controller. The load controller confirmed that the pallet should have been offloaded, and was therefore not included in the uplift weight calculations. The load controller then contacted the Qantas Integrated Operations Control (IOC) in Sydney and advised them that a pallet had been loaded onto the aircraft, which was not included in the load sheet, and that some operational limitations had been exceeded.

About 75 minutes after the aircraft departed from Bangkok, the IOC advised the aircraft flight crew of the error. The flight crew entered the amended aircraft weight into the flight management computer.

Load discrepancy

The weight of the standby pallet for 23P indicated on the LIR was 2,785 kg. The final load sheet indicated 1,225 kg of freight in compartment 2. Compartment 2, depicted in Figure 1, included a number of freight positions including 23P. The calculation for total freight weight in Compartment 2 was based on freight loaded in positions 26L (615 kg), 26R (610 kg) and zero in 23P.

Based on the final load sheet, the taxi weight was calculated to be 235,485 kg (maximum 233,900 kg) and the take-off weight was 232,300 kg (maximum 233,000 kg).

As a result of the discrepancies, Qantas advised that the maximum taxi weight had been exceeded by 1,585 kg, and the maximum take-off weight by 2,085 kg. The initial cruise altitude of 35,000 ft did not exceed the maximum altitude when the actual weight was subsequently entered into the aircraft flight management computer.

Qantas investigation

Qantas conducted an investigation into the incident, which included a review of the transfer of load control operations to Warsaw (from its previous location in Hong Kong), the systems supporting the load controller and loading supervisor, and their individual actions.

The investigation identified a number of safety factors that contributed to the incident. These included the following.

Depiction of standby freight

The load controller represented the standby freight as listed on the LIR, with the freight depicted in the loaded position, and a standby notation included in the Special Instructions box. The Qantas investigation found that was not a documented procedure for handling standby freight, but it was an accepted practice. The training of loading supervisors did not include how standby freight was to be documented on the LIR.

Communication

The communications between the loading supervisor and load controller were open to misinterpretation, had ambiguous phraseology, untimely transmissions, and did not involve a read-back hear-back process.

During the partial read back, the offload instruction caused confusion as to whether the pallet in 23P was to be loaded or not, and that confusion was not resolved.

During the final read back, a misunderstanding resulted from the load controller’s use of the phrase ‘no fit’, meaning not loaded, and the loading supervisor’s use of the phrase ‘no change’ meaning no change to the loading depicted on the LIR.

Training

Irregularities were identified with the training regarding LIR presentation and interpretation. Specifically, the training on procedures for handling standby items provided to load controllers did not cross-reference the training provided to loading supervisors and vice versa.

Safety actions

Whether or not the ATSB identifies safety issues in the course of an investigation, relevant organisations may proactively initiate safety action in order to reduce their safety risk. The ATSB has been advised of the following proactive safety action in response to this occurrence.

Aircraft operator

As a result of this occurrence, Qantas advised the ATSB that they are taking the following safety actions:

Immediate action taken

For all flights out of Bangkok, the loading supervisor must receive a scanned copy of the final LIR before transmitting the final load sheet to the flight crew (by ACARS).

Standard phraseology is to be used for all read back communications.

Standby freight procedure

Load Control will document the following:

• procedures for listing standby freight in the LIR Special Instructions
• use of LIR Special Instructions
• sample communications for instructions to offload and the required response from loading supervisors.

Training

The training provided to load controllers and loading supervisors was to be coordinated. The training procedures will include a standardised process for handling standby freight.

A process for updating load control training material will also be implemented.

Firstload

An automated read back system, ‘Firstload’, is scheduled to be introduced to Bangkok and other international ports in November 2015. Firstload is an iPad-generated LIR and read back system. Implementation of the system will remove the requirement for verbal read backs.

Safety message

This incident highlights the importance, particularly when dealing with safety-critical data, for:

• standard phraseology in verbal communications
• ensuring a verbal instruction has been understood and complied with
• validating verbal communication with written documentation.

The ATSB SafetyWatch highlights the broad safety concerns that come out of our investigation findings and from the occurrence data reported to us by industry. One of the safety concerns is data input errors.

Data input errors, such as the wrong figure being used, happen for many reasons. The consequences of these errors can range from aborted take-offs, to collisions with the ground. More information is available in the ATSB safety research report, Take-off performance calculation and entry errors: A global perspective.

Aviation Short Investigations Bulletin - Issue 45

Purpose of safety investigations The objective of a safety investigation is to enhance transport safety. This is done through: identifying safety issues and facilitating safety action to address those issues providing information about occurrences and their associated safety factors to facilitate learning within the transport industry. It is not a function of the ATSB to apportion blame or provide a means for determining liability. At the same time, an investigation report must include factual material of sufficient weight to support the analysis and findings. At all times the ATSB endeavours to balance the use of material that could imply adverse comment with the need to properly explain what happened, and why, in a fair and unbiased manner. The ATSB does not investigate for the purpose of taking administrative, regulatory or criminal action. Terminology An explanation of terminology used in ATSB investigation reports is available here. This includes terms such as occurrence, contributing factor, other factor that increased risk, and safety issue. Publishing information  Released in accordance with section 25 of the Transport Safety Investigation Act 2003 Published by: Australian Transport Safety Bureau © Commonwealth of Australia 2015 Ownership of intellectual property rights in this publication Unless otherwise noted, copyright (and any other intellectual property rights, if any) in this report publication is owned by the Commonwealth of Australia. Creative Commons licence With the exception of the Coat of Arms, ATSB logo, and photos and graphics in which a third party holds copyright, this publication is licensed under a Creative Commons Attribution 3.0 Australia licence. Creative Commons Attribution 3.0 Australia Licence is a standard form licence agreement that allows you to copy, distribute, transmit and adapt this publication provided that you attribute the work. The ATSB’s preference is that you attribute this publication (and any material sourced from it) using the following wording: Source: Australian Transport Safety Bureau Copyright in material obtained from other agencies, private individuals or organisations, belongs to those agencies, individuals or organisations. Where you wish to use their material, you will need to contact them directly.

__________

1. No fit means that the position is empty.

 

Safety summary

What happened

On 28 July 2015, the pilot and owner of an amateur-built Cicaré CH-7BT helicopter, registered VH‑JEW, was conducting a ferry flight from Indee Station to Roy Hill Station, Western Australia. When about 8.5 NM north‑east of Roy Hill Station, the stabiliser assembly fractured leading to an in-flight break up and collision with terrain. The pilot, and sole occupant, was fatally injured and the helicopter was destroyed.

What the ATSB found

The ATSB examined the helicopter wreckage and identified that the stabiliser had separated in‑flight from the tail boom as a result of fatigue cracking of the stabiliser mount. This was the second fatal accident in Australia involving in-flight stabiliser separation on a Cicaré CH-7B helicopter (In-flight break-up involving Cicaré CH-7B, VH-SWQ, 43 km north-west of Barcaldine Airport Queensland on 12 May 2014 (AO-2014-086)). Following the event in 2014, the helicopter manufacturer, Cicaré S.A., released a mandatory service bulletin, BSC007, which required inspection of the stabiliser assembly. However, the bulletin did not include an initial or recurrent time interval for that inspection.

The ATSB found that there were notable differences between VH-JEW and SWQ, and the accidents were not directly comparable. However, it was established that both helicopters were fitted with an external storage pod, likely without the appropriate engineering assessment to ensure there would be no adverse effects on the performance, handling and structure of the helicopter. In addition, both helicopters had previously been used for mustering operations, although the helicopters were designed be used for recreational use only. The ATSB found other Cicaré CH-7B owners were also likely using their helicopters for aerial mustering and other agricultural activities. The addition of unapproved modifications and use for mustering operations can produce unintended stresses on the airframe leading to premature failure of components.

The ATSB determined that a combination of factors could have contributed to the development of the fatigue crack including, the stabiliser design, operating the helicopter in high load mustering activities, and the use of untested accessories. However, the investigation was unable to determine the contribution of these factors.

What's been done as a result

On 6 August 2015, the ATSB emailed an information letter to registered Cicaré CH-7B owners, informing them of the second accident, the mechanism of stabiliser failure, and a recommendation to ensure the integrity of the stabiliser prior to further operation and on an ongoing basis.

The ATSB has also released a Safety Advisory Notice (AO-2015-089-SAN-014) to raise awareness among amateur-built helicopter owners and the aerial mustering community regarding the risks associated with operating outside the recommended design intent.

A revision to the original bulletin, BSC007, was released in September 2015, which provided some additional information with regard to disassembly of the component to allow examination. The contents of this bulletin was incorporated into the ongoing maintenance documentation for the helicopter in March 2016, with the inspection required to be performed every 100 hours. The stabiliser was also redesigned, originally for the bigger CH-8 series helicopter. The latest design was incorporated into all new Cicaré helicopters and is available for retrofit on the CH-7T/B/BT. A number of operators in Australia have already installed the new stabiliser assembly.

Safety message

The addition of external loads may result in forces in excess of the manufacturer’s limitations. This accident highlights the significance of ensuring that any modifications, such as external accessories, are appropriately assessed, and the effects on structural integrity and handling characteristics are considered prior to flight.

Further, it emphasises the importance of operating aircraft in accordance with the manufacturer’s intent and limitations. Operating outside these has the potential to induce stresses on the aircraft, leading to premature wear and possible failure.

Lastly, as detailed in the information letter released in March 2016, the ATSB reinforces the importance of CH-7B owners ensuring the integrity of the stabiliser on an on-going basis. If any doubt arises concerning the inspection or maintenance of any part, piece or component, owners should immediately contact Cicaré.

Appendices

Appendix A – ATSB information letter

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Safety issues and actions

The safety issues identified during this investigation are listed in the Findings and Safety issues and actions sections of this report. The Australian Transport Safety Bureau (ATSB) expects that all safety issues identified by the investigation should be addressed by the relevant organisation(s). In addressing those issues, the ATSB prefers to encourage relevant organisation(s) to proactively initiate safety action, rather than to issue formal safety recommendations or safety advisory notices.

Depending on the level of risk of the safety issue, the extent of corrective action taken by the relevant organisation, or the desirability of directing a broad safety message to the [aviation, marine, rail - as applicable] industry, the ATSB may issue safety recommendations or safety advisory notices as part of the final report.

All of the directly involved parties were provided with a draft report and invited to provide submissions. As part of that process, each organisation was asked to communicate what safety actions, if any, they had carried out or were planning to carry out in relation to each safety issue relevant to their organisation.

The initial public version of these safety issues and actions are repeated separately on the ATSB website to facilitate monitoring by interested parties. Where relevant the safety issues and actions will be updated on the ATSB website as information comes to hand.

Cicaré S.A. CH-7T/B/BT service bulletin

Safety issue number: AO-2015-089-SI-01

Safety issue description: The Cicaré 7T/B/BT mandatory service bulletin (BSC007) for the general stabiliser support assembly provided limited guidance for disassembly of the manufactured component and did not stipulate a compliance period within which to perform the inspection nor provide consideration for repeat inspections. This potentially reduced the opportunity to detect the presence of crack initiation and growth in the stabiliser support assembly.

Additional safety actions

Whether or not the ATSB identifies safety issues in the course of an investigation, relevant organisations may proactively initiate safety action in order to reduce their safety risk. The ATSB has been advised of the following proactive safety action in response to this occurrence.

Additional safety action taken by Cicaré S.A.

Cicaré have advised that they are intending to release a revision to the Pilot’s Operating Handbook at the end of January 2020, which will indicate that the helicopters are not intended or recommended for aerial work, particularly mustering operations, which can cause a significant increase of loads and affect the fatigue life.

ATSB safety advisory notice to owners of Cicaré CH-7B and the agricultural aerial mustering community

Action number: AO-2015-089-SAN-014

Operating a helicopter within the stated design intent and limitations is essential for safe conduct of flight. The ATSB advises owners/operators of amateur-built experimental aircraft to be fully aware of the risks associated with this category of aircraft and that operation outside the limitations prescribed by the manufacturer, such as the addition of unapproved modifications and use for mustering operations, can produce unintended stresses on the airframe leading to premature failure of components.

ATSB information letter

On 6 August 2015, an information letter was emailed to registered Cicaré CH-7B owners, informing them of the second accident, the mechanism of stabiliser failure and a recommendation to ensure the integrity of the stabiliser prior to further operation and on an ongoing basis. The content of the letter is included as an Appendix and is also available on the

.

Context

Pilot information

The pilot held a Commercial Pilot (Helicopter) Licence, issued on 13 June 1980. The pilot last completed a single-engine helicopter and low-level flight reviews in June 2015, valid until 30 June 2017 and 24 June 2017 respectively.

At the time of the accident, the pilot’s Class 1 Aviation Medical Certificate required for conducting commercial operations^[2] had expired on 13 April 2015 and the pilot was in the process of revalidation. The pilot held a Class 2 certificate, valid to 13 April 2016.

In May 2015, the pilot indicated on his aviation medical questionnaire that he had accumulated a total of 28,559 hours, with 78 hours of helicopter operations in the previous 6 months. The pilot was reported to have had extensive experience as a cattle mustering pilot. Anecdotal information supplied to the ATSB indicated that most of this flying had been completed in a Robinson Helicopter Company R22. The pilot had only recently starting flying the Cicaré CH-7BT, and it was reported that the pilot had been conducting commercial mustering operations^[3] in the weeks leading up to the accident.

Witness reports from family and acquaintances indicated that the pilot was in good health and mental state prior to the flight. A post-mortem examination did not reveal any preconditions that would have affected the pilot’s ability to fly the helicopter.

Helicopter information

VH-JEW was a single-seat, amateur-built^[4] Cicaré CH-7BT helicopter, serial number 032, which was first registered with the Civil Aviation Safety Authority (CASA) on 25 June 2015 (about one month before the accident). It had a two‑bladed, semi-rigid main rotor system, a two-bladed tail rotor system, and was powered by a Rotax 914 UL turbo-charged, four-cylinder piston engine. The helicopter kit manufacturer was located in Argentina with the kits and product support available through an Australian distributor. As at March 2019, there had been 39 CH-7B^[5] kits sold worldwide, 13 of which were in Australia. At time of publication, there were six on the CASA VH‑register.

Meteorological information

Personnel on the ground at Ginbata aerodrome (about 10 NM from the accident site) described the weather conditions on the day as fine and clear with light wind. This was consistent with the Bureau of Meteorology area forecasts for the afternoon.

Sunset was recorded to be at 1737 and last light^[6] at 1801. The helicopter departed Indee Station at about 1535, which would have put the arrival time at Roy Hill at about 1800. However, a worker at the nearby Roy Hill mining camp reported seeing black smoke for about 20 minutes at about 1720. Therefore, it was considered unlikely that the weather and available light conditions were a contributing factor to the accident.

Wreckage and impact information

The helicopter was found in an open area, having broken into multiple fragments. The fuselage was subject to a post-impact fire, and the tail rotor stabiliser assembly was identified some distance away from the main wreckage (Figure 2).

Figure 2: Wreckage distribution showing main body and tail rotor stabiliser assembly, the blue arrow shows direction of travel

Source:  ATSB

The stabiliser assembly and the tip from one tail rotor blade were the first items identified in the wreckage trail. The main rotor head components were located about 70 m beyond the stabiliser. The tail boom was still attached to the main wreckage, which was lying on its left side and facing opposite to the intended direction of travel, and was a further 180 m along. The tail rotor gearbox assembly was located near the fuselage. Overall, the wreckage distribution was about 250 m long in a southerly direction and consistent with an in-flight break-up.

The helicopter had been subjected to a post-impact fire, which destroyed much of the fuselage. Examination of the remaining wreckage identified:

• all major components of the helicopter were accounted for
• flight control damage was consistent with the in-flight break-up and did not indicate any pre‑existing issues
• no indications of any issues with the engine and its related systems that may have contributed to the accident
• the stabiliser assembly had separated at the point where it mounted to the tail boom
• the tail rotor gearbox had fractured at its mount in overstress
• the main rotor head assembly had separated from the main mast in a manner consistent with severe mast bumping.^[7]

The fracture surfaces of the stabiliser assembly attachment bracket that remained with the tail boom appeared to correspond to those of the separated stabiliser assembly in shape and irregular texture. The rear section of the tail boom, including tail rotor components and the stabiliser assembly were retained by the ATSB for further examination (see Stabiliser assembly below).

Similar occurrence

The ATSB investigated a similar fatal accident where the stabiliser assembly on a Cicaré CH-7B had separated from the tail in-flight leading to a collision with terrain (In-flight break-up involving Cicaré CH-7B, VH-SWQ 43 km north-west of Barcaldine Airport Queensland on 12 May 2014 (AO-2014-086)). The investigation found that fatigue cracking of the stabiliser mount had led to the failure of the stabiliser assembly. The helicopter was reported to have had an issue with airframe vibration, and thee stabiliser had undergone two weld repairs following the identification of cracking of the stabiliser mount tube. The first weld repair was at about 130 hours’ total time-in-service, after the fins were removed following reports of movement within the stabiliser structure. The second weld repair was performed at about 295 hours’ total time-in-service. The investigation found these repairs were performed by a welder who did not hold a CASA-issued aviation welding authority, and that the first unauthorised welding carried out on the mount did not prevent further in-service metal fatigue cracking. The helicopter had also experienced a hard landing, sufficient to distort the rear cross-tube on the skid-landing gear. The investigation also found that the helicopter had undergone modifications, including the addition of heli-baskets and larger fuel tanks, which were not approved by CASA and/or the kit manufacturer, and could have affected the serviceability and flight characteristics.

Following this accident, the ATSB sent an advisory letter to all Australian registered owners of the CH-7B on 6 March 2015 which detailed the in-flight separation of the stabiliser.

The kit manufacturer advised that the accidents involving VH-SWQ and VH-JEW were the only known stabiliser fractures in the worldwide fleet of Cicaré 7 series helicopters^[8].

Stabiliser assembly

The stabiliser assembly consisted of one horizontal and two vertical aerodynamic fins fitted to the helicopter tail boom. The fins generate aerodynamic forces during forward flight that keep the helicopter level and reduce the thrust required from the tail rotor.

Flight characteristics without stabilisers

The kit manufacturer advised that they had performed testing of the flight characteristics of the helicopter when the stabiliser assembly was not fitted and found the following:

…proving that for hovering flight condition and low speeds, the change in controllability was verily [sic] noticeable and for translational flight over 30 knots the helicopter showed a light instability in pitch and yaw that can be easily corrected by the pilot, a pilot with standard training is able to execute the emergency maneuver [sic].

However, the manufacturer also noted that:

In case of loss of stabilizer [sic] in flight, even if the stabilizer doesn’t hit the tail rotor, sudden change on aerodynamic loads and CG [centre of gravity] balance due to the sudden absence of the stabilizer would cause an unstable flight condition.

With regard to the failure of the tail rotor/gearbox, the manufacturer advised:

For the case of an eventual tail rotor loss, during flight-testing there was no presence of “loss tail rotor effectiveness” under normal flight operations. In case of tail rotor or tail rotor gearbox failure, due to the variety of conditions that may occur it’s not possible to determine the exact behaviour of the aircraft.

Assembly build and fitting

While the build manual provided instructions for manufacturing this component, the kit manufacturer and Australian distributor advised that the CH-7B kits for Australia were supplied with the stabiliser assembly as a pre-assembled component (inset, Figure 3).

Figure 3: Stabiliser assembly showing location of fracture on VH-JEW

Source: Cicaré, modified by the ATSB

The CH-7BT kit build manual provided instructions for fixing the stabiliser on the tail boom. A factory pre-drilled hole in the stabiliser mount was to be positioned 115 mm forward of the tail rotor gear box mount and aligned with the top centreline of the tail boom. A hole was then drilled into the boom skin, using the locator hole as a guide, and a bolt inserted through the mount and boom.

Technical examination of the stabiliser assembly

While it was outside the scope of the investigation to conduct an engineering assessment of the helicopter design, a detailed examination of the retained tail components was conducted at the ATSB’s technical facilities in Canberra, with a focus on the fracture of the stabiliser support. That examination found that the failure had occurred adjacent to the welded region of the support. The location of the cracking was also coincident with the point at which the upper and lower vertical stabiliser fairings met the mount (Figure 4).

Figure 4: Location of the stabiliser failure adjacent to the welded region

Source:  ATSB

Stabiliser mount

The stabiliser fins were removed from the stabiliser assembly in order to completely expose both portions of the fractured stabiliser mount (Figure 5). The stabiliser mount was comprised of three main sections; a clamp for attaching to the tail boom, conical support, and three oval-shaped, thin‑walled seamless metal tubes that were used to locate and secure the fins into position (Figure 5). During manufacture at the factory, the three tubes had been cut to fit and then welded together at the conical support.

Figure 5: Location of the stabiliser failure following removal of the fins

Source: ATSB

Detailed microscopic examination of the stabiliser mount fracture surfaces was accomplished using a binocular microscope. The examination revealed that the fracture path primarily followed the welded portions of the tube junction. A large portion of the fracture surface was discoloured, and exhibited fretting and corrosion product along with the presence of a series of finely spaced continuous progression marks. Such features were consistent with a fatigue crack growth mechanism as a result of in-service cyclic stresses and suggested that the crack had been present for some period of time prior to final fracture.

The fatigue crack had propagated in a circumferential manner through about 75 per cent of the structure prior to the failure (Figure 6). Once a significant portion of the cross section had fractured, the remaining section could no longer sustain in-flight loads and the stabiliser failed due to overstress. The origin of the fatigue cracking could not be clearly identified due to post‑accident damage. No obvious defects or anomalies were observed in the welded regions that might have otherwise contributed to the growth of the fatigue cracking.

Figure 6: Stabiliser fracture surface showing fatigue and overstress areas

Source:  ATSB

Sectioning of the fracture surface for detailed microstructural examination and hardness testing did not reveal the presence of any anomalies that might have contributed to the failure. Chemical analysis of the stabiliser mount tubes was consistent with an SAE grade 4130 steel, as specified by the manufacturer.

Comparison between the stabiliser mount of VH-JEW and VH-SWQ

The two stabilisers had failed in a similar location, however, three differences were observed between the construction of the stabiliser mount of VH-JEW and VH-SWQ^[9] including:

• The vertical and horizontal tubes had been manufactured from welded tube for VH-SWQ, and seamless tube for VH-JEW.^[10]
• The mount on VH-SWQ was hollow through the joins in the horizontal tube where the vertical tubes were attached (Figure 7 left). For VH-JEW, the horizontal tube was not hollow (intact tube) where the vertical tubes were attached (Figure 7 right).

The horizontal tube for VH-JEW was welded at the conical support, while for VH-SWQ the tube was welded in two locations – at the conical support and just outboard of the intersection with the vertical tubes. (Figure 7 left).

Figure 7: Comparison between stabiliser fracture on VH-SWQ (left) and VH-JEW (right)

Source: ATSB

VH-JEW information and history

Construction and certification

VH-JEW was constructed as an amateur-built and experimental (ABE) aircraft under the Civil Aviation Safety Regulations 1998 (CASRs) Part 21 Subpart H, and Civil Aviation Regulations 1988 (CAR 1988) 262AP. Regulation 21.191 outlined the reasons an experimental certificate may be issued. Referring to the operation of amateur-built aircraft, sub-part (g) stated: ‘the major portion of which has been fabricated and assembled by a person who undertook the construction project solely for the person’s own education or recreation’. CASA Advisory Circular AC-21.4(2) Amateur-built Experimental Aircraft – Certification, provided guidance and information to those applying for an experimental certificate.

An aircraft that does not have a standard certificate of airworthiness^[11] cannot operate unless it has been issued with a special certificate of airworthiness (including an experimental certificate) or a special flight permit. According to CASA Advisory Circular AC-21.10 v4.2 (issued March 2019), Experimental certificates:

Special certificates of airworthiness (CofA), which include experimental certificates, are issued to permit certain kinds of operations of aircraft that do not meet the requirements for a standard CoA or that, because of certain modifications, do not conform to their type certificates, but are capable of safe operations under defined operating conditions and purposes.

In recognition of the lack of compliance with some of the airworthiness standards, the aircraft is normally permitted to be operated under more restrictive operating conditions than in the case of a comparable aircraft operating on a standard CofA.

An authorised person (AP)^[12] could issue experimental certificates under CASR 21.195A to allow operation of amateur-built and kit-built aircraft. This special certificate of airworthiness detailed the conditions under which the aircraft was permitted to be operated. For example, the helicopter involved in the previous ATSB investigation (refer to Similar occurrence), VH-SWQ, had a special certificate of airworthiness with a condition that it was not to be flown for commercial operations.

Under the experimental certificate, ABE aircraft were inspected at least once prior to the initial test flight by CASA or by an AP, who may operate under the Sport Aircraft Association of Australia (SAAA) maintenance procedures. Advisory Circular AC-21.4(2) described that the purpose of the inspection was to:

allow the inspector to make a subjective assessment of the workshop methods, techniques and practices used in the construction of the aircraft solely for the purpose of prescribing appropriate conditions and operating limitations necessary to protect other airspace users and persons on the ground or water, i.e. to protect persons and property not involved in the activity.

As part of the certification process, an ABE aircraft was initially limited to operations within an assigned flight test area for at least 25 hours, to demonstrate it was capable of safe flight.

VH-JEW was built by the pilot and owner in south-east Queensland in early 2015 from a kit supplied by the manufacturer. It was reported to the ATSB that the helicopter build took longer than the pilot expected. Below is a timeline of the events related to the helicopter build:

• 26 March 2015: The pilot initially contacted the SAAA requesting an onsite inspection of VH‑JEW on 4 May 2015.^[13] According to documentation provided by the SAAA, that visit was cancelled and rescheduled as the helicopter was not ready for inspection.
• The onsite inspection was rescheduled to 27 May 2015, however, it was again delayed as the helicopter was not ready for inspection.^[14]
• 3 June 2015: The pilot submitted an application for a special certificate of airworthiness in the experimental (kit-built) category.
• 4 June 2015: A visit was carried out by the SAAA AP, however, it was reported that the helicopter was still not completed, and some of the required documentation was not completed or available. Following that visit, the pilot continued discussions with the SAAA about completion of the relevant requirements. The outstanding items were not related to the stabiliser or tail boom assemblies.
• 16 June 2015: The SAAA AP received an email containing a copy of the helicopter logbook and test flight record pages, dated 28 June 2015, indicating that 26.2 flight hours had been completed.^[15]
• 25 June 2015: The helicopter was registered with CASA.
• 15 July 2015: As the SAAA AP had not issued the authorisation for test flights to commence, a letter was sent to the pilot,^[16] advising that:

You are currently flying your aircraft without a Certificate of Airworthiness

The process of submitting the requested information listed on previous email has not been received

Copies of certifications for duplicate inspections from airframe log book not received

Submission of the nominated pilots and nominated flight test area not received.

As a result, the SAAA advised that they were unable to proceed any further with the application at that time. Due to the limited timeframe between when the letter was dated, and the date of the accident, the investigation could not be assured that the pilot had received the letter.

Helicopter flight history

Following the build, the pilot departed Queensland in VH-JEW on the morning of 27 June 2015 and arrived in Western Australia on the evening of 29 June 2015. At the time of the accident, the most recent entry on the maintenance release (5 days prior on 23 July 2015) showed the helicopter had accumulated 168.7 hours’ total time-in-service. Of the eight entries recorded, six of them showed the helicopter had accumulated between 8.3 and 11 hours on these days. This, together with information supplied by associates of the pilot, indicated that it was likely that the helicopter had been involved in some (commercial) aerial work, including aerial stock mustering and/or spotting, since arriving in Western Australia. It was also reported that the pilot was generally happy with the operation of the helicopter, and had not mentioned any major issues or the presence of vibrations.

Following the accident, a colleague of the pilot stated that there was a report of the temperature gauge reading above the normal operating range, however, it was mentioned that it was a one‑time occurrence and the reason for this was not determined. An acquaintance of the pilot reported to the ATSB that the pilot had advised him that the helicopter had experienced a hard landing in early July 2015, but it didn’t appear to have caused any damage to the helicopter.

Airworthiness and maintenance

Under sub-regulation 42ZC(6) of CAR 1988, the owner/builder of an amateur-built aircraft may be authorised to carry out maintenance on the aircraft, if they were the primary builder. CASA Instrument 33/13 Authorisation of person to carry out maintenance on certain amateur-built, kit‑built and light sport aircraft with a special certificate of airworthiness, detailed the conditions of the owner/builder’s maintenance authorisation. One of the conditions was that the owner/builder was required to have satisfactorily completed a course in maintenance procedures.^[17] Further, maintenance conducted could only be on the elements of the aircraft that they had assembled.

The most recent maintenance release, issued by the pilot on 16 July 2015, at 105.9 hours’ total time‑in‑service, indicated the helicopter was to be maintained in accordance with the manufacturer’s maintenance schedule manual. The maintenance manual recommended a complete inspection of the helicopter every 12 months or 100 hours’ time-in-service. This included:

During inspection, check the general condition of the components and observe if there is evidence of damage, color change due to high temperatures, dents, scratches, notches, corrosion and specially cracks. Also check for any sign of friction in the parts that are near one another.

Specific to the stabilisers, the manual stated the following:

Check the whole surface of the stabilizers. Verify there are no scratches or cracks.

Check each stabilizer bearing. Verify there are no cracks around the attachment holes. Also check that the attachment screws are in proper condition.

Check the tailskid. Verify if there is evidence of strikes against the ground.

As the helicopter logbooks were not located, the ATSB was unable to determine what, if any, maintenance and/or inspections had been carried out on VH-JEW since leaving Queensland.

In addition, the ATSB also noted that there were several omissions and inaccuracies with how the maintenance release had been completed, making it invalid. However, as the aircraft had not been authorised for flight operations, it was determined there would be little benefit in further investigation. While these irregularities did not likely contribute to the accident, continued operation and maintenance outside of the regulations increases the risk that the safety protections they offer will be eroded.

Manufacturer’s stabiliser mount inspection

Following the accident involving VH-SWQ (refer to Similar occurrence), the manufacturer released a service bulletin on 24 September 2014 (BSC007) requiring dye penetrant inspection of the stabiliser. This document included instructions on how to perform the testing on the stabiliser mount. However, there was no mention of how to remove the support assembly from the horizontal and vertical fins to perform the inspection, which would have been necessary to inspect the relevant area. For VH-JEW, as this component had been pre‑assembled by the manufacturer for import into Australia, this maintenance would need to have been performed by an appropriately qualified person, such as a licensed aircraft maintenance engineer. Additionally, the document did not include any inspection interval requirements (initial or recurrent). The manufacturer reported that owners were advised to evaluate the stabiliser mount every 100 hours, or if there were any signs of wear on the stabiliser. No evidence was supplied to the ATSB as to how this information had been disseminated to owners.

External storage pod

The helicopter had been modified with an external storage pod, attached to the rear strut of the right skid-landing gear (Figure 8). The storage pod was not included on the weight and balance documents provided as part of the special certificate of airworthiness approval process. It was reported that this pod was fitted for the flight from Queensland to Western Australia. However, as the helicopter logbooks were not located, the ATSB was unable to establish if the storage pod remained fitted for the life of the helicopter, or if any authorisations^[18] had been received.

Figure 8: External storage pod as fitted to VH-JEW at Indee Station on 23 July 2015

Source: Andrew Miles, annotated by the ATSB

Helicopter landing gear is designed to provide energy absorbing capabilities during landing. Fixing external loads to the landing gear can result in forces applied to the landing gear in excess of the design limit and can also increase the in-flight dynamic loads due to increased vibration. Advice published by Robinson Helicopter Company for the R22 in the pilot operating handbook included a safety notice, SN-13, which stated that;

…even a small weight attached to the landing gear may change the natural frequency^[19] enough to cause high loads to inflight vibration.

The ATSB could not determine whether the potential effects on the in-flight loads, flight characteristics and operating weight were considered by the pilot prior to the fitment of the external storage pod.

The Cicaré CH-7B was promoted in the Australian website Beef Central^[20] in a 19 April 2011 article Heli-mustering game-changer, which included the promotion of the use of an external storage box:

While the Cicaré has a payload limit of around 100kg (not including pilot), it can be set up with a storage box to carry a chainsaw, fencing tools and enough wire for many on-the-job fencing repairs, for example.

However, correspondence from the kit manufacturer advised that the helicopter was not designed to carry external loads, and had not been tested under asymmetrical load conditions. The kit manufacturer was of the opinion that the difference between the two helicopters with cracked stabilisers and the rest of the Cicaré fleet with unaffected stabilisers was the addition of accessories (the storage pod in the case of VH-JEW and a heli-basket and larger fuel tanks for VH-SWQ), ‘making it very hard to ignore that this [sic] accessories could be related to the premature wear of the stabilizer’.

Ground handling

The flight manual contained the procedures for moving the helicopter on the ground, using the wheels provided, which attached to the landing gear. These procedures stipulated that the helicopter was to be pushed or pulled by holding the tail rotor gearbox. Additionally, the flight manual included the following caution:

Do not move [the] Cicaré CH-7BT by holding either the horizontal or vertical stabiliser, or from the tail rotor, or the tail rotor controls, or tailskid.

Manoeuvring the helicopter via the tail skid, particularly over rough terrain, could induce unintended forces on the stabiliser mount. However, as the pilot’s ground handling practices could not be established, the ATSB was unable to determine if this contributed to the development of the stabiliser mount fatigue crack.

Commercial flying

In order to conduct commercial aerial work operations, including aerial mustering and spotting, at the time of the accident, the pilot was required to hold a Commercial Pilot Licence. Additionally, Civil Aviation Regulations 1988 (CAR) 206 stated that an Air Operator’s Certificate was also required to conduct commercial operations.

The pilot held a Commercial Pilot Licence (Helicopter), and had regularly conducted commercial flying operations in helicopters. The pilot also held an AOC, on which two Robinson Helicopter Company R22’s were listed. VH-JEW was not listed on the Air Operator’s Certificate.

Operational aspects

The Cicaré S.A. website stated that the Cicaré CH-7B was a helicopter ‘for sport use’. However, the Australian experience indicated that these helicopters were increasingly being used for agricultural operations and other aerial work, such as mustering and spotting.

Both VH-SWQ and VH-JEW had been used for mustering operations during their lifetime, and the ATSB was aware of one other reported accident involving another Cicaré CH-7B helicopter while engaged in agricultural operations in October 2018.

While the use of an amateur-built helicopter for private agricultural operations, including mustering and spotting, was not specifically excluded under the CASA regulations, such operations can involve extremely frequent manoeuvring and rapid power changes that can apply very high loads on the helicopter. The fatigue life of various components can be adversely affected by the type of operation and loading history of the components. CASA Airworthiness Bulletin (AWB) 02-015 Helicopter – Effects on fatigue on life limited components described some operational situations where the fatigue life might be affected, and included:

…Operations of helicopters in low level flying, agricultural, mustering or other operations where high loads may be encountered more frequently than envisaged by the designer/manufacturer.

Cicaré CH-7B flying activity

Activity data for the CH-7B between 2011 and 2018 was supplied by the Bureau of Infrastructure, Transport and Regional Economic (BITRE) is shown in Table 1.^[21] This data was reported to BITRE by registered aircraft owners in the annual BITRE General aviation activity survey.

Table 1: Reported flights and hours for Cicaré CH-7B aircraft between 2011 and 2018

	2011	2012	2013	2014	2015	2016	2017	2018
Number of aircraft	3	4	8	4	7	5	6	5
Number of landings	24	35	62	10	89	51	293	562
Total hours	17	28	52	19	83	43	457	408
Private	17	28	52	-	-	-	-	-
Agriculture mustering	-	-	-	0	6	0	0	0
Agriculture-other	-	-	-	19	0	19	397	0
Other aerial work	-	-	-	0	0	0	0	181
Pleasure and personal transport				0	48	8	57	7
Other sport and pleasure flying	-	-	-	0	29	16	3	7
Other flying	-	-	-	0	0	0	0	213

Source: Bureau of Infrastructure, Transport and Regional Economics

The data showed that only 6 hours total had been attributed to agricultural mustering over this period. However, in 2017-2018, there was a significant increase in the reported landings/hours for the Cicaré CH-7B fleet, together with an increase in the number of hours attributed to ‘agricultural-other’ (which includes all non-mustering and non-spraying agricultural activities including stock spotting), other aerial work and other flying categories.

The manufacturer advised that a number of helicopters within the fleet had accumulated up to 400 hours in Argentina and at least one helicopter in Australia had reached 1,500 hours total time-in-service. However, they were unable to provide any information on what types of operations these helicopters may have been performing when these house were accumulated.

Previous research

Stress loads from aerial stock mustering and spotting

In 2004, the ATSB commissioned AeroStructures, an Australian engineering company, to undertake a study of the forces acting on a Robinson Helicopter Company (RHC) R22 (also extensively used in mustering operations in Australia) while engaged in aerial mustering operations. The study (

) provided a comparison of the flight profiles in aerial mustering operations and compared these with the flight profiles used during certification.

The report found that aerial mustering exhibited frequent low speed manoeuvres and rapid power changes, and five measurements showed higher peak stresses than for the certification flights, one of which was the tail rotor drive shaft torque. The report stated that:

Owners and operators need to fully appreciate the stresses placed on aircraft during mustering operations, and the characteristics of aerial mustering operations, which may be quite different [to] the type of flying for which the type originally received certification

Advice was contained in a safety notice produced by the Robinson Helicopter Company, who manufactured the R22 helicopter. Safety Notice, SN-37 - Exceeding approved limitations can be fatal discussed how fatigue damage can accumulate within components without a visible indicator.

The kit manufacturer, Cicaré S.A, advised that

experimental category covers recreational and sport use. However, this won't prohibit anyone to use it for other activities.

Amateur-built aircraft research

ATSB research has identified that amateur-built aircraft are over-represented in aviation accidents and incidents in Australia (AR-2007-043 (2) Amateur-built aircraft Part 2: Analysis of accidents involving VH-registered non-factory-built aeroplanes 1988-2010). The research found that, although pilots of amateur-built aircraft involved in accidents were significantly more experienced overall than pilots of accidents in equivalent factory-built aircraft, they were less experienced on the type that they were flying at the time of the accident.

While this report did not include amateur-built helicopters due to the small numbers in operation at that time, much of the data and outcomes of the report were relevant to aeroplanes and helicopters. The prevalence of amateur-built helicopters in Australia is also increasing.

__________

2. A Class 1 medical certificate is required whenever a pilot is exercising the privileges of a Commercial Pilot’s Licence. Since March 2018, holders of a Commercial Pilot’s Licence can undertake some operations with a Class 2 medical certificate. This is, a commercial flight with no passengers on-board and in an aircraft with a maximum take-off weight of less than 8,618 kg.
3. Civil Aviation Order 29.10 defines aerial mustering as ’the use of aircraft to locate, direct and concentrate livestock while the aircraft is flying below 500 feet above ground level’. Further, ’aerial mustering may be conducted as a private operation over land occupied by the owner of the aircraft or as an aerial work operation’. The pilot had been conducting aerial work in VH-JEW.
4. An amateur-built aircraft is an aircraft, the major portion (more than 50 per cent) of which has been fabricated and assembled by a person who undertook the construction project solely for their own education or recreation (CASA Advisory Circular AC21.4(2) Amateur-built Experimental Aircraft – Certification). An amateur-built aircraft can be built from scratch, based on original or established designs, or from a kit.
5. Cicaré CH-7B included both the CH-7B and CH-7BT variants.
6. Last light can also be referred to as the end of evening civil twilight.
7. Mast bumping: contact between the main rotor hub and the rotor mast, which, if excessive, could severely damage the mast, or result in the separation of the main rotor system from the helicopter. Damage from mast bumping is indicative of excessive blade flapping and/or excessive tilt of the main rotor disc relative to the mast.
8. The Cicaré 7 series included the CH-7B, CH-7BT and CH-7T models. No CH-7T kits have been imported into Australia.
9. The manufacturer advised that the change from welded to seamless tube, and difference in weld locations, occurred between helicopter serial number 11 (VH-SWQ) and serial number 32 (VH-JEW).
10. Welded tube is formed from a metal strip that is roll formed and welded to produce a tube. A seamless tube does not have any welded seam.
11. A standard certificate of airworthiness is issued to individual Australian aircraft that meet the International Civil Aviation Organization Annex 8 Airworthiness of Aircraft requirements, and have been issued with a type certificate.
12. CASA authorises persons to act on behalf of CASA in the inspection of amateur built aircraft and the issue of airworthiness certificates. The authorised person inspects the aircraft to assess it conforms to applicable CASA administrative requirements.
13. It was likely that this inspection was scheduled prior to the build start as the pilot reportedly flew from Western Australia to Perth on 8 April 2015.
14. The pilot’s family stated that some of the delays were due to having to wait for components to arrive from Argentina.
15. A discrepancy between the dates the SAAA reported receiving the email from the pilot, and the date on the helicopter logbook was noted. This discrepancy could not be reconciled from the information available, but was considered that the reported date of the email was incorrect, and was likely closer to 15 July 2015.
16. At the same time, the SAAA also advised CASA who initiated a process to follow up with the pilot.
17. It could not be established if the pilot had completed a maintenance procedures course. The SAAA did not have a copy of the course certificate on file for the pilot, however, the ATSB was advised that the pilot could have attended a course and not applied to receive a certificate. The helicopter importer was of the belief that the pilot had completed a course.
18. Under regulation 42U of Civil Aviation Regulations 1988, a person may only modify an aircraft if the modification is approved. For an amateur-built experimental aircraft, there are no design standards against which a modification can be approved, so CASA Instrument number EX51/15 exempted limited category and experimental aircraft from those requirements. However, the exemption was not applicable where the modification or repair was considered a major design change. A major design change was defined as ‘a design change that has a significant effect on (a) the weight and balance of the aircraft; or (b) the structural strength of the aircraft; or (c) the performance of the aircraft; or (d) the operational characteristics of the aircraft; or (e) other characteristics that may affect the validity of the special certificate of airworthiness or the experimental certificate for the aircraft’.
19. Natural frequency is the frequency at which a system tends to oscillate in the absence of any driving or damping force.
20. BeefCentral.com is a free online premium news and market intelligence service dedicated to the Australian beef industry.
21. The operation categories recorded by BITRE changed between 2013 and 2014. For the 2011-2013 data, the available categories included; private, business, test and ferry, training, survey and photography, pipe and powerline patrol, mustering, S&R, ambulance, towing, other aerial work, agriculture, charter, regional RPT. From 2014, the categories were expanded, and included; advertising, aerobatics, agricultural mustering, agricultural spreading/spraying, agriculture-other, air ambulance, construction, domestic, ferry flights, firefighting, glider towing, instructional flying, international, joyflights/sightseeing, observation and patrol, other commercial air transport, other aerial work, other flying, other sport and pleasure flying, own use business travel, parachute dropping, passenger transport charters, photography, pleasure and personal transport, S&R, pipeline or powerline surveying, test flights, freight only-scheduled, freight only - non-scheduled, construction-sling loads, other surveying, policing, instructional flying -non-commercial, community service flights

The occurrence

On 28 July 2015, at about 1535 Western Standard Time,^[1] the pilot and owner of an amateur-built Cicaré CH-7BT helicopter, registered VH-JEW, departed Indee Station for a 2.5-hour flight to Roy Hill Station, Western Australia. The flight was a repositioning flight, for mustering work at Roy Hill Station, which was to commence the following day.

At about 1810, a company pilot who had arrived at Roy Hill Station about 2 hours prior, phoned another pilot who had remained at Indee Station to advise that VH-JEW had not yet arrived. They decided to give the pilot a little more time, however, when the helicopter still had not arrived by about 1930, it was reported missing to search and rescue, and the police. A search and rescue operation commenced the following morning.

On 29 July 2015, at about 1500, the wreckage was located about 8.5 NM north-west of Roy Hill Station, and 0.5 NM west of the intended track between Indee and Roy Hill Stations (Figure 1). The pilot was fatally injured, and the helicopter destroyed.

Figure 1: VH-JEW accident site location, near Roy Hill Station

Source: Google earth, annotated by the ATSB

__________

1. Western Standard Time (WST): Co-ordinated Universal Time (UTC) + 8 hours.

Findings

From the evidence available, the following findings are made with respect to the collision with terrain of a Cicaré CH-7BT helicopter, registered VH-JEW, that occurred near Roy Hill Station, Western Australia on 28 July 2015. These findings should not be read as apportioning blame or liability to any particular organisation or individual.

Safety issues, or system problems, are highlighted in bold to emphasise their importance. A safety issue is an event or condition that increases safety risk and (a) can reasonably be regarded as having the potential to adversely affect the safety of future operations, and (b) is a characteristic of an organisation or a system, rather than a characteristic of a specific individual, or characteristic of an operating environment at a specific point in time.

Contributing factors

• While conducting a ferry flight, the stabiliser mount fractured, resulting in an in-flight break-up and collision with terrain.
• The helicopter’s stabiliser mount fractured due to overstress, following propagation of a fatigue crack in the area adjacent to the weld. While the ATSB was unable to fully determine the reasons for the intiation and propagation of the fatigue crack, it was likely the result of some combination of the design, operating conditions, and untested accessories.

Other factors that increased risk

• The helicopter was modified with an external storage pod, likely without the appropriate engineering assessment to ensure there would be no adverse effects on the performance, handling and structure of the helicopter.
• Although the amateur-built Cicaré CH-7B helicopter was intended for recreational and sport use only, this and other CH-7B helicopters had been used for agricultural mustering. Operating outside the manufacturer’s design intent had the potential to induce stresses on the aircraft, leading to premature wear of components and possible failure.
• The Cicaré 7T/B/BT mandatory service bulletin (BSC007) for the general stabiliser support assembly provided limited guidance for disassembly of the manufactured component and did not stipulate a compliance period within which to perform the inspection nor provide consideration for repeat inspections. This potentially reduced the opportunity to detect the presence of crack initiation and growth in the stabiliser support assembly. [Safety issue]

Other findings

• The helicopter was being operated without a Civil Aviation Safety Authority special certificate of airworthiness. Further, it was being used for commercial mustering operations, however, as an amateur-built experimental helicopter it would very likely not have been approved to conduct such operations. In addition, while the pilot had significant aeronautical experience, his Class 1 Aviation Medical Certificate had expired and although in the process of renewing it, the pilot was unable to exercise the privileges of his Commercial Pilot’s Licence.

Safety analysis

While on a ferry flight from Indee Station to Roy Hill Station, Western Australia, the stabiliser assembly on VH-JEW fractured leading to an in-flight break-up and collision with terrain. The pilot was fatally injured, and the aircraft was destroyed.

Available information indicated that it was unlikely that the pilot became incapacitated during the flight, and pilot fatigue, weather and poor manufacturing of the welded stabiliser structure were not considered factors.

This analysis will examine the potential factors that may have led to the failure of the stabiliser and resulting in-flight break-up.

In-flight break-up

The fracture of the stabiliser mount and subsequent in-flight separation of the stabiliser from the tail boom led to severe mast bumping sufficient to sever the mast and main rotors. Consistent with the wreckage distribution, the helicopter broke up in-flight, resulting in a collision with terrain.

In the event of a stabiliser failure, the manufacturer indicated that, although the helicopter was theoretically controllable under certain circumstances, the sudden change to the aerodynamic loads and centre of gravity balance, would lead to an unstable flight condition. Additionally, this was the second accident where a loss of control had resulted following the loss of the stabiliser assembly.

Stabiliser mount cracking

Analysis of the tail components identified that the stabiliser assembly mount was significantly weakened by cracking associated with metal fatigue. While the ultimate fracture of the mount was due to overstress, a fatigue crack was found to have propagated about 75 per cent of the way around the mount’s circumference, adjacent to the welded region. The investigation considered the potential factors that contributed to the cyclical loading that resulted in fatigue cracking of the stabiliser mount. These included, in no particular order:

• fitment of the external storage pod
• possible operations exceeding the manufacturer’s limitations
• stabiliser assembly design.

The helicopter had been fitted with an external storage pod attached to the rear strut of the right skid‑landing gear, although it was unknown if it was in place on the accident flight. The storage pod was not on the weight and balance documents associated with the special certificate of airworthiness process, and a special certificate of airworthiness had not been issued. While the helicopter logbooks were not located, it was unlikely that an engineering assessment had been conducted prior to the helicopter departing Queensland.

In addition, the manufacturer indicated that the helicopter was not designed to carry external loads and expressed reservations about the addition of an accessory on both VH-JEW and VH-SWQ. Specifically, they were of the opinion that the fitment of the external accessories to both these aircraft could have been the reason for the premature failure of the stabiliser. The fitment of the pod had the potential to adversely affect the structural integrity and handling characteristics of the helicopter. However, as it was likely the pod had not been assessed, the ATSB was unable to determine the extent to which this contributed to the initiation and propagation of the fatigue crack.

While the Australian activity data indicated minimal mustering activity in the CH-7B, the ATSB was aware of three accidents where the helicopter had, at some point, been conducting this type of operation. For VH-JEW, the investigation was able to establish that the helicopter had operated for 168.7 hours up until 23 July 2015, and likely only a few hours on the day of the accident. The available records indicated that in the month prior to the accident, it had been used for at least 60 hours of low-level mustering operations. The Cicaré CH-7B helicopter is advertised as being for recreational use, and operation outside the manufacturer’s limitations has the potential to induce stresses on the airframe and components, leading to premature wear and possible failure. Further, operations such as mustering and similar activities can also increase the risk of premature ageing of aircraft structure due to an increased load spectra.

In addition, while two aircraft in Australia exhibited premature failure of the same component, in a similar location, at relatively low time in-service, these were the only two helicopters in the worldwide fleet to exhibit cracking. While there were some similarities between the accidents involving VH-SWQ and VH-JEW, in that both helicopters had been fitted with untested external accessories and were being used for mustering operations, there were some notable differences. VH-SWQ had experienced a number of other issues, including a hard landing and ongoing airframe vibrations possibly, as a result of a tail rotor imbalance, which may also have contributed to the development of a fatigue crack within the stabiliser mount. In addition, the design of the stabiliser had been modified for helicopter kits manufactured after VH-SWQ, including VH-JEW. Therefore, it was not possible to make a direct comparison between the two accidents.

While it was outside the scope of the investigation to conduct an engineering assessment of the helicopter design, the stabiliser mount has been shown to be susceptible to fatigue cracking of under certain conditions. However, if there was an inherent design issue with the helicopter, it was not unreasonable to expect more incidence of cracking in the worldwide fleet. This was particularly so given a number of helicopters in the fleet had accumulated up to 400 hours in Argentina and at least one helicopter in Australia had reached 1,500 hours total time-in-service. However, VH-JEW and VH-SWQ were the only helicopters that have exhibited cracking. As a result, the investigation was unable to determine the contribution of all factors such as design, operating conditions, untested accessories, and the magnitude of the effect these elements may have had on the development of the fatigue crack.

Manufacturer’s service bulletin

Following the accident involving VH-SWQ in 2014, the manufacturer released a mandatory service bulletin, BSC007, to all operators of the Cicaré 7 series helicopters. While the service bulletin provided a general instruction to perform a non-destructive dye penetrant inspection of the stabiliser mount, it did not include essential information such as how to disassemble the stabiliser to perform the inspection, a compliance time, or a recurring inspection interval.

Given the extent of the fatigue crack found on the stabiliser mount, it was likely that the crack had been present for some time since the helicopter entered service. However, the absence of a compliance timeframe or requirement for a recurring inspection reduced the likelihood of the crack being detected prior to reaching a critical size. Additionally, as the bulletin was released prior to the pilot purchasing and building the helicopter, it was possible that he did not have knowledge of the requirement to conduct the inspection.

Airworthiness documentation and regulatory aspects

Amateur-built experimental aircraft are not required to comply with the full range of safety regulations that are applicable to commercially manufactured aircraft. However, the regulations that do apply are fundamentally important and have been introduced to control and reduce (as much as possible) the risks associated with the operation of this category of aircraft.

At the time of the accident, the aircraft had not been issued with a Civil Aviation Safety Authority (CASA) special certificate of airworthiness. As a result, the aircraft was not on the operator’s Air Operator’s Certificate, and therefore, not authorised to be flown for commercial aerial work such as aerial spotting or mustering. Not having the certificate meant that compliance with the applicable airworthiness standards could not be assured.

In addition, as an amateur-built experimental helicopter, it was very likely that the special certificate of airworthiness would have been issued with prescriptive operational uses, which would not have included commercial mustering. It was reported that the pilot had been conducting commercial aerial mustering operations in the helicopter in the weeks leading up the accident and was intending to continue after arriving at Roy Hill Station.

While the pilot had significant aeronautical experience and held a valid Class 2 Aviation Medical Certificate, the pilot’s Class 1 certificate had expired several months prior. Although he was in the process of revalidation, the pilot was unable to exercise the privileges of a Commercial Pilot’s Licence until such time. Of note, the pilot had no apparent medical issues.

The ATSB had considered if the pilot was experiencing time or commercial pressures to complete the build of VH-JEW. However, due to the limited information available, this could not be established. Therefore, the ATSB was unable to determine if this had influenced his actions with regard to the aircraft certification process.

The pilot’s decision not to follow certain regulations may not have directly influenced the in‑flight break-up of the stabiliser assembly. However, it did result in the helicopter being used for commercial mustering operations that it was not authorised for and would very likely not have been approved for by the Civil Aviation Safety Authority. This exposed the helicopter to higher operational stress and had the potential to increase the risk to the pilot and those working around the helicopter during the flying operations.

Sources and submissions

Sources of information

The sources of information during the investigation included the:

• The Civil Aviation Safety Authority
• Western Australia Police and Coroner
• Cicaré S.A.
• The Australian importer of Cicaré S.A. kits
• Bureau of Meteorology
• Sport Aircraft Association of Australia
• Bureau of Infrastructure, Transport and Regional Economics.

References

Australian Transport Safety Bureau (2004), Robinson R22 helicopter and aerial mustering usage investigation (B2004/0292). Retrieved from

.

Australian Transport Safety Bureau (2013). Amateur-built aircraft Part 2: Analysis of accidents involving VH-registered non-factory-built aeroplanes 1988-2010 (AR-2007-043(2)). Retrieved from www.atsb.gov.au/media/4097175/ar-2007-043_2__final.pdf.

Australian Transport Safety Bureau (2016), In-flight break-up involving Cicaré CH-7B, VH-SWQ 43 km north-west of Barcaldine Airport Queensland on 12 May 2014 (AO-2014-086). Retrieved from

.

Civil Aviation Safety Authority (2006), Airworthiness Bulletin (AWB) 02-015 Helicopter – Effects on fatigue on life limited components. Retrieved from https://www.casa.gov.au/files/awb-02-015-issue-1-helicopter-effects-fatigue-life-limited-components.

Civil Aviation Safety Authority (2000), Advisory Circular AC-21.4(2) Amateur-built Experimental Aircraft – Certification. Retrieved from www.casa.gov.au/files/021c04pdf.

Robinson Helicopter Company (2001), R22 Pilot’s Operating Handbook – Section 10, Safety Tips and Notices, Safety Notice SN-37. Retrieved from https://shop.robinsonheli.com/wp-content/uploads/2022/01/r22_poh_10.pdf.

Submissions

Under Part 4, Division 2 (Investigation Reports), Section 26 of the Transport Safety Investigation Act 2003 (the Act), the Australian Transport Safety Bureau (ATSB) may provide a draft report, on a confidential basis, to any person whom the ATSB considers appropriate. Section 26 (1) (a) of the Act allows a person receiving a draft report to make submissions to the ATSB about the draft report.

A draft of this report was provided to Cicaré S.A., the Civil Aviation Safety Authority, the Sport Aircraft Association of Australia, the distributor of Cicaré helicopters in Australia, and the pilot’s next of kin.

Submissions were received from Cicaré S.A., the Civil Aviation Safety Authority, and the pilot’s next of kin. The submissions were reviewed and, where considered appropriate, the text of the report was amended accordingly.

Purpose of safety investigations & publishing information

Purpose of safety investigations The objective of a safety investigation is to enhance transport safety. This is done through:  identifying safety issues and facilitating safety action to address those issues providing information about occurrences and their associated safety factors to facilitate learning within the transport industry. It is not a function of the ATSB to apportion blame or provide a means for determining liability. At the same time, an investigation report must include factual material of sufficient weight to support the analysis and findings. At all times the ATSB endeavours to balance the use of material that could imply adverse comment with the need to properly explain what happened, and why, in a fair and unbiased manner. The ATSB does not investigate for the purpose of taking administrative, regulatory or criminal action. Terminology An explanation of terminology used in ATSB investigation reports is available here. This includes terms such as occurrence, contributing factor, other factor that increased risk, and safety issue. Publishing information Released in accordance with section 25 of the Transport Safety Investigation Act 2003 Published by: Australian Transport Safety Bureau © Commonwealth of Australia 2019 Ownership of intellectual property rights in this publication Unless otherwise noted, copyright (and any other intellectual property rights, if any) in this report publication is owned by the Commonwealth of Australia. Creative Commons licence With the exception of the Coat of Arms, ATSB logo, and photos and graphics in which a third party holds copyright, this publication is licensed under a Creative Commons Attribution 3.0 Australia licence. Creative Commons Attribution 3.0 Australia Licence is a standard form licence agreement that allows you to copy, distribute, transmit and adapt this publication provided that you attribute the work. The ATSB’s preference is that you attribute this publication (and any material sourced from it) using the following wording: Source: Australian Transport Safety Bureau Copyright in material obtained from other agencies, private individuals or organisations, belongs to those agencies, individuals or organisations. Where you wish to use their material, you will need to contact them directly.

What happened

On 27 July 2015, the pilot of an Eagle DW1 aircraft, registered VH-FHP, was conducting aerial spraying operations on a property about 77 km southeast of Townsville, Queensland. The pilot completed aerial spraying of two paddocks, and then loaded the aircraft with about 450 L of chemical (about half capacity), and half a tank of fuel.

At about 0930 Eastern Standard Time (EST), the pilot took off to spray the third paddock for that day. The pilot overflew the paddock and identified two sets of powerlines. The pilot formed a plan to spray the paddock using a racetrack pattern and flying it in a clockwise direction. One set of powerlines ran parallel to the spray direction, and the other ran across it at the western end. There was a line of trees along the western powerline, which obscured vision of the power poles.

The pilot completed the first spray run towards the western powerline, overflew it, and then turned to line up for the second spray run (Figure 1). A small area of about 30 m of trees had been cleared for a pump installation and the clearing was in line with the start of the second spray run. The pilot noted the powerline ahead, but then diverted their attention to the other powerline, running parallel to the direction of flight, and about 5 m off the left wingtip. The pilot also looked inside at the GPS to check the aircraft’s line for the spray run.

Figure 1: Paddock to be sprayed showing powerlines and wirestrike location

Source: Google earth and the pilot of VH-FHP – annotated by the ATSB

The pilot commenced the descent into the paddock through the clearing in the trees and did not see the powerline at that time. As the aircraft descended, the pilot looked up and suddenly sighted the powerline. The pilot elected to push forwards on the controls to make the aircraft descend. The aircraft then struck the powerline above the propeller on the wing struts.

After the aircraft struck the wires, it yawed violently to the left. The pilot used the right rudder to turn the aircraft away from the other powerlines, and the force of the aircraft pulled the transformer off the power pole on the left. The aircraft then yawed to the right. The force broke the power pole on the right and severed the powerline.

The aircraft decelerated rapidly, and the wires pulled the aircraft towards the ground. The pilot landed the aircraft with the wings level. The landing gear sheared off, the propeller struck the ground and the aircraft ground-looped, coming to rest facing the opposite direction. The pilot sustained minor injuries and the aircraft was destroyed (Figure 2).

Figure 2: VH-FHP at the accident site showing damage to the aircraft and wires

Source: Aircraft operator

Pilot comments

The pilot provided the following comments:

• The pilot had sprayed that paddock once previously, and had used an anticlockwise racetrack pattern. On that occasion, as the power poles were on the eastern side of the trees, they were more visible from that direction.
• The pilot elected to descend after sighting the powerline, to prevent the landing gear from potentially catching on the wires and flipping the aircraft over.
• The aircraft had a wire cutter on the undercarriage and a wire deflector between the top of the wing and the tail, but not on the struts where the wire struck.
• The powerlines were three phase.

Safety message

The pilot was aware of the powerline the aircraft collided with, but did not have it front-of-mind at the start of the spray run. The pilot’s attention was diverted to other powerlines, parallel to the direction of flight, and also inside the aircraft to the GPS. The pilot reported that stating aloud ‘powerlines ahead’, would have helped to maintain awareness of the wires.

The Aerial Agricultural Association of Australia suggests a way to keep focus is to ask yourself:

• Where is the wire now?
• What do I do about it?
• Where am I in the paddock?

For further risk management strategies for agricultural operations, refer to the Aerial Application Pilots Manual.

The ATSB research report Aerial application safety: 2014-2015 year in review, stated that aerial application operations have a high accident rate relative to other aviation sectors. These operations involve inherent risks. Those risks include low-level flying, high workloads and obstacles such as powerlines. More than half of the total accidents and serious incidents over the past 10 years were wirestrikes.

The report also stated that it is important to constantly monitor the environment, so the hazards that were identified in pre-planning can be recognised and avoided. If a pilot is not specifically looking for a hazard, it is unlikely they will notice it.

The ATSB investigated a similar accident, involving a Robinson R66 helicopter. A copy of that report is available here: AO-2014-142.

Read more about: Wirestrikes involving known wires: A manageable aerial agriculture hazard

 Wirestrike involving known wires: A manageable aerial agriculture hazard

Aviation Short Investigations Bulletin - Issue 43

Purpose of safety investigations The objective of a safety investigation is to enhance transport safety. This is done through: identifying safety issues and facilitating safety action to address those issues providing information about occurrences and their associated safety factors to facilitate learning within the transport industry. It is not a function of the ATSB to apportion blame or provide a means for determining liability. At the same time, an investigation report must include factual material of sufficient weight to support the analysis and findings. At all times the ATSB endeavours to balance the use of material that could imply adverse comment with the need to properly explain what happened, and why, in a fair and unbiased manner. The ATSB does not investigate for the purpose of taking administrative, regulatory or criminal action. Terminology An explanation of terminology used in ATSB investigation reports is available here. This includes terms such as occurrence, contributing factor, other factor that increased risk, and safety issue. Publishing information  Released in accordance with section 25 of the Transport Safety Investigation Act 2003 Published by: Australian Transport Safety Bureau © Commonwealth of Australia 2015 Ownership of intellectual property rights in this publication Unless otherwise noted, copyright (and any other intellectual property rights, if any) in this report publication is owned by the Commonwealth of Australia. Creative Commons licence With the exception of the Coat of Arms, ATSB logo, and photos and graphics in which a third party holds copyright, this publication is licensed under a Creative Commons Attribution 3.0 Australia licence. Creative Commons Attribution 3.0 Australia Licence is a standard form licence agreement that allows you to copy, distribute, transmit and adapt this publication provided that you attribute the work. The ATSB’s preference is that you attribute this publication (and any material sourced from it) using the following wording: Source: Australian Transport Safety Bureau Copyright in material obtained from other agencies, private individuals or organisations, belongs to those agencies, individuals or organisations. Where you wish to use their material, you will need to contact them directly.

 

Safety summary

What happened

On 24 July 2015, container freight train 6MC2 lost two containers from the train as it passed through Bowser, north of Wangaratta. The two containers lost from the train landed clear of the track on the eastern side. The train continued its journey with the crew unaware of the incident.

At about 0430 the following morning, the driver of another freight train noticed a container and reported it to train control.

What the ATSB found

The ATSB found that it was very likely that the twist locks that secured the containers to the train were ineffective prior to the incident. This condition allowed the unsecured containers to fall from the train. It is probable that strong winds contributed to the movement of the unsecured containers. Other external forces, such as train and track dynamics, may have also contributed to the movement. However, there was no evidence of such contribution.

Given the containers were located some distance behind the locomotives, and that no other train operational systems were affected when they fell from their respective wagons, the train crew were not aware of the incident.

What's been done as a result

As a result of the incident, Pacific National undertook an internal investigation into the incident and has taken action to:

• initiate a process to include checks for twist lock operation as part of wagon maintenance and inspection
• develop a twist lock inspection manual
• update freight loading manuals to include methodology for identifying defective twist locks
• update wagon maintenance manual to include methodology for identifying defective twist locks
• update twist lock training materials to include identification of defective twist locks
• initiate a review of twist lock integrity history
• initiate a review of twist locks currently in service – supply and type
• calculate the failure rate of twist locks across the Intermodal fleet for probability and risk mitigation considerations.

Safety message

Rail operators should satisfy themselves that their procedures can ensure that all twist locks are effective at securing freight containers to their respective wagons before the transit of trains.

Safety actions

Additional safety action

Whether or not the ATSB identifies safety issues in the course of an investigation, relevant organisations may proactively initiate safety action in order to reduce their safety risk. The ATSB has been advised of the following proactive safety action in response to this occurrence.

Pacific National

As a result of the incident, Pacific National undertook an internal investigation into the incident and completed the following actions:

• initiate a process to include checks for twist lock operation as part of wagon maintenance and inspection
• develop a twist lock inspection manual
• update freight loading manuals to include methodology for identifying defective twist locks
• update wagon maintenance manual to include methodology for identifying defective twist locks
• update twist lock training materials to include identification of defective twist locks
• initiate a review of twist lock integrity history
• initiate a review of twist locks currently in service – supply and type
• calculate the failure rate of twist locks across the Intermodal fleet for probability and risk mitigation considerations.

The occurrence

At about 1428 on 24 July 2015, container freight train 6MC2 departed Appleton Dock, Melbourne headed for Griffith, New South Wales. The train was programmed to detach wagons at certain locations along the standard gauge route. Train 6MC2 was owned and operated by Pacific National (PN). The train consisted of three locomotives (two were off line) hauling 60 wagons, was 1272 m long, with a total mass of 2051 t. The train was a scheduled service, transporting containers between Melbourne and Griffith.

At about 1805, train 6MC2 passed through Wangaratta travelling on the east track. A short time later near Bowser (North Wangaratta), the train passed V/Line passenger train 8630 on the west track heading to Melbourne. A little further on, the train crew noticed the trees alongside the track swaying violently in a localised storm event. The crew commented that the wind swayed the locomotive. At this point, unbeknown to the train crew, two containers fell off the train.

The train continued on its programmed journey towards Griffith. At Ettamogah, 13 wagons were detached, but the missing containers were not noticed.

At about 0430 on 25 July 2015, the driver of freight train 3PW4 (travelling on the west track) sighted a shipping container lying next to, but clear of, the east track between Wangaratta and Springhurst at the 244.500 track km point. The driver reported the container to the Australian Rail Track Corporation (ARTC) Network Control Centre South located at Junee, New South Wales. The ARTC network control centre warned another following train, XPT passenger train ST21 travelling from Sydney to Melbourne on the east track, to proceed at caution. At 0447, the driver of ST21 confirmed the details and location of the container with the ARTC network control centre.

Figure 1: Containers laying adjacent the track

Note: The blue container in the foreground was located on the 17th wagon. The red container in the background was located on the 13th wagon. The direction of travel shown with a red arrow. Source: Pacific National

The ARTC arranged to have the track inspected. At about 0634, the inspector arrived on site and discovered a second shipping container near the track. Both containers were clear of the track and normal train running resumed.

The ARTC established that the containers had fallen from train 6MC2 the previous night. By then, seven trains had passed the location since the containers were lost from train 6MC2. Of the seven passing trains, five were on the West track and two on the East track.

Safety analysis

Twist locks

Containers are loaded onto suitable rail vehicles and secured at each corner by twist locks. Pacific National’s Freight Loading Manual^[1] (FLM) details specific requirements for securing containers to wagons. The manual specifies:

• All devices used to secure containers to rail wagons must be in a sound and serviceable condition.
• All containers MUST have all four securing devices locked in position prior to transit.

There are four types of approved securing devices:

• Portable twist locks (automatic operation)
• Portable twist locks (manual operation)
• Portable anchor brackets
• Internal hook type
• External clamp type
• Retractable fixed twist locks
• Hinged type
• Pop up type

Patrick Port Logistics (PPL) loaded the two containers that subsequently fell from train 6MC2. PPL also had requirements^[2] for securing containers to rail wagons. These requirements largely reflected the Pacific National (PN) specific requirements. On the day of the incident, PPL used eight automatic twist locks, one on each corner, securing both containers to the rail wagons. PPL used a combination of two Gavan, one Celtec Cel-Lock TFA, and five Celtec Cel-Lock TFAD twist locks, Figure 2 and Figure 4.

Figure 2: Twist lock types

Source: Pacific National

The normal position of an automatic twist lock is in the locked position, Figure 3. When a container is loaded onto a rail wagon the container pocket unlocks the twist lock head. When the container is fully seated, the twist lock head returns to the locked position, securing the container. When a container is unloaded, the lifting action applies sufficient force to unlock the twist lock head and releases the container.

If a twist lock sticks, operators can release the lock manually. Twist locks are fitted with an emergency release pin and/or a visual safety indicator. Once released manually, operators must manually reset before the next use. Loading staff can visually inspect these indicators (indicator and/or pin) to ascertain the state of the twist lock.

Figure 3: Twist lock engagement

Note: Celtec TFAD type twist lock showing unlocked and locked positions. Source: Celtec.

Following the incident, PN found the twist locks still fastened to the rail wagon. One lock was broken and all others were in the unlocked position, as shown in Figure 4.

Figure 4: Twist lock layout as found

Note: Based on ‘as found’ condition by PN.

Twist lock inspection

Following the incident, Pacific National commissioned a report to investigate the condition of the twist locks. A specialist inspected the twist locks from both wagons to determine the serviceability of them. The report notes:

All but one twist lock was in open position when collected. 2 X Gavan + 1 X first generation Celtec TFA had broken Emergency Release (See new design Celtec TFAD and TFAE how the house is designed so that ER is not exposed to impact as much as the old TFA). 2 X Celtec TFAD could be returned to activated position. 1 X Celtec TFAD had a broken shaft. The twist locks should not have been in use as they were not activated or could not be activated…

It is concluded that containers MAGU5655514 and MRKU8741873 were able to break free from their respective wagons due to twist locks being in poor condition rendering them completely ineffective.

Based on the condition of the twist locks, and supported by the specialist report, it is very likely that the twist locks were not working prior to the incident. This condition allowed the containers to fall from the train. Given the distance behind the locomotives, dark light condition, and that no other train operational systems were affected, the train crew were not aware of the incident.

Furthermore, the generally poor condition of the twist locks, including serviceability, was not detected particularly during the pre-loading, or post loading inspections. Before loading, twist locks must be inspected for serviceability before use. Any unserviceable twist locks are quarantined from further use until repaired. After loading, the twist locks are not specifically checked during pre-departure or in-service inspections. Although the FLM provides guidance on pre-loading inspection of twist locks, there is no other guidance available to perform adequate post-loading inspections.

At no stage were the defective twist locks identified. In this case, allowing ineffective twist locks to enter service affected the safe transit of the train.

Environmental conditions

Both drivers of train 6MC2 commented on abnormal weather conditions north of Wangaratta. The conditions were such that the leading locomotive was shaken as debris was blown across the track.

Weather station data was obtained from the Bureau of Meteorology (BOM) located at Wangaratta aero, about 12 km from the incident site. At 1500, on the day of the incident, the temperature was recorded as 11 °C, 99 per cent relative humidity, and wind from the north at 13 km/h. In addition, data was obtained from a local council weather station at Bowser, about 6 km from the incident site. At the time of the incident, this data recorded the temperature as 12 °C, 94% relative humidity, and wind from the southwest at 17 km/h.

Notwithstanding the weather data, the train crew witnessed a weather event. Based on the proximity of the Bowser weather station, the event was most likely localised. The local council had no reports of storm damage.

Weather effect on train 6MC2

The Rail Industry Safety and Standards Board (RISSB) provides guidelines^[3] on calculating wind force on railway vehicles. These guidelines were used to determine minimum wind force needed to unlock twist locks (in good condition and effective) and blow the containers off the train.

Based on the characteristics of the wagons, a perpendicular wind speed in excess of 160 km/h would be needed to apply sufficient lifting force to unlock the twist locks and tip the containers off. There is no evidence of a weather event in that location generating wind speeds in excess of 160 km/h.

Summary of environmental conditions

There was no evidence that environmental conditions existed that were severe enough to tip containers, if secured by effective twist locks.

However, considering the post incident condition of the twist locks in this case, it is probable that the weather witnessed by the train crew contributed to the movement of the unsecured containers (Figure 5). Other external forces, such as train and track dynamics, may have also contributed to the movement however, there was no evidence of such contribution.

Figure 5: Wind affect

Related occurrences

The Office of the National Rail Safety Regulator (ONRSR) maintains a database of occurrence events reported. A review of that database for the previous 12 months showed 28 reported instances of containers found with ineffective twist locks in service.

Based on this data, it is not uncommon to find ineffective twist locks in service. Although the container remained on the rail vehicle in most instances, the risk of loss still existed.

Findings

From the evidence available, the following findings are made with respect to the loss of containers from train 6MC2 near Bowser, Victoria, on 24 July 2015. These findings should not be read as apportioning blame or liability to any particular organisation or individual.

Contributing factors

• A localised weather event probably shifted the inadequately secured containers from the wagon.
• The twist locks were in an unserviceable condition meaning that they did not engage during loading. The containers were not adequately restrained during transit.
• Pacific National had documented instructions for pre-loading inspections, but in this case the poor condition of the twist locks was not detected.
• Pacific National did not have any documented instructions requiring post-loading inspection for twist lock effectiveness.

__________

1. Freight Loading Manual FLM 03-08_10.
2. Patrick Port Logistics Integrated Management System Securing of Containers to Rail Wagons: GOP 5.10
3. RISSB Australian Standard AS 7509.2

Purpose of safety investigations & publishing information

Purpose of safety investigations The objective of a safety investigation is to enhance transport safety. This is done through: identifying safety issues and facilitating safety action to address those issues providing information about occurrences and their associated safety factors to facilitate learning within the transport industry. It is not a function of the ATSB to apportion blame or provide a means for determining liability. At the same time, an investigation report must include factual material of sufficient weight to support the analysis and findings. At all times the ATSB endeavours to balance the use of material that could imply adverse comment with the need to properly explain what happened, and why, in a fair and unbiased manner. The ATSB does not investigate for the purpose of taking administrative, regulatory or criminal action. Terminology An explanation of terminology used in ATSB investigation reports is available here. This includes terms such as occurrence, contributing factor, other factor that increased risk, and safety issue. Publishing information  Released in accordance with section 25 of the Transport Safety Investigation Act 2003 Published by: Australian Transport Safety Bureau © Commonwealth of Australia 2016 Ownership of intellectual property rights in this publication Unless otherwise noted, copyright (and any other intellectual property rights, if any) in this report publication is owned by the Commonwealth of Australia. Creative Commons licence With the exception of the Coat of Arms, ATSB logo, and photos and graphics in which a third party holds copyright, this publication is licensed under a Creative Commons Attribution 3.0 Australia licence. Creative Commons Attribution 3.0 Australia Licence is a standard form licence agreement that allows you to copy, distribute, transmit and adapt this publication provided that you attribute the work. The ATSB’s preference is that you attribute this publication (and any material sourced from it) using the following wording: Source: Australian Transport Safety Bureau Copyright in material obtained from other agencies, private individuals or organisations, belongs to those agencies, individuals or organisations. Where you wish to use their material, you will need to contact them directly.

What happened

On the afternoon of 26 July 2015, the pilot prepared a PA32-300 (Cherokee Six) aircraft, VH-BDG (BDG), for a private joy flight around the Whitsunday Islands off the Queensland coast, (Figure 1) departing from the Lakeside Airpark. The pilot had arranged for five acquaintances to come on the flight as passengers.

About a week earlier, the pilot, who had an injured right foot at the time, organised another pilot to fly BDG on a re-positioning flight to the Lakeside Airpark. Due to being unable to fly the re-positioning flight, the accident flight became the pilot’s first time operating from the Airpark.

Pilot recollections

The pilot reported that they delivered a safety brief outlining the relevant safety features of the aircraft, just prior to loading the passengers. After loading the four rear passengers, the pilot secured the left rear cargo door, and then entered the cockpit through the front right door, followed by the front seat passenger.

The flight departed at about 1400 Eastern Standard Time (EST), and remained outside controlled airspace. The flight overflew some of the Whitsunday Island group as well as the outer reef area of the Great Barrier Reef, prior to setting a return course to the Airpark about one and half hours later (Figure 1).

Figure 1: A google earth extract showing the general area where the joyflight was conducted

Source: Google earth, annotated by the ATSB

The pilot approached the extended centreline at an oblique angle and conducted a straight in approach to runway 22 (Figures 2 and 3). When about 6 NM from the airfield, at about 2,300 ft above mean sea level, the aircraft was configured for descent. After reducing the airspeed from about 135 to about 100 kt, and with 10° of flap selected, the aircraft descended to about 1,800 ft.

Figure 2: An extract from the Queensland Country Airstrip Guide. Diagrammatic representation of Lakeside Airpark and local hazards

Source: Queensland Country Airstrip Guide, 2012 edition

Figure 3: Approach to runway 22 at Lakeside Airpark. Note the unsealed and sealed portion of the runway. Also, note the difficulty in detecting the power lines on approach. Photo taken about a week prior to the accident

Source: Barry Dionysius

In order to maintain sufficient clearance over the two rows of power lines, and still land near the threshold, well before the sealed section of the runway, the pilot planned a steeper approach than normal. The flap was set to 40° (full flap) and the rate of descent increased to about 500-600 feet per minute.

On short final, the aircraft suddenly began to sink rapidly, and the pilot recalled seeing a tree pass close by the left window. Judging that the aircraft was now too low; the pilot applied full power, held the aircraft nose in a raised position, turned the aircraft left toward lower ground, and initiated a go-around.

However, the aircraft continued to sink throughout this manoeuvre, and the tail struck the runway about 20 m in from the threshold. Throughout this attempt to go-around, the tail continued to drag along the gravelled section of the runway, leaving a mark about 30-35° to the left of the runway direction for about 18m.

Although not yet showing a positive rate of climb, the aircraft seemed to be flying. The pilot reported that the stall warning had not sounded, so assessed there was a choice between removing the power and attempting to land back on the runway, or continuing with the go-around. The pilot elected to continue with the go-around and continued toward the lower ground.

A witness mark made by the right wheel, commenced at about the same spot where the mark made by the tail stopped. The wheel mark continued for about 35m into the grassed area beside the runway.

Once into the grassed area, and with the aircraft most probably airborne, it struck a wire fence (Figure 4) then the raised embankment of the dam, which ran perpendicular to the runway. The pilot reported that the left wing tip struck the water and the aircraft spun around and entered the water. At some point throughout this sequence, the main wheels detached from the aircraft. The pilot reported continuing to battle for control of the aircraft, up until it arrived in the water.

Figure 4: Looking along runway 22 taken a few days after the accident

Source: Pilot

Post water impact

When the aircraft settled on the surface of the water, the pilot reported yelling to the passengers to ‘get out’. The pilot then opened the front right door, pushed the passenger occupying the front right seat out, and then exited. The opening of the door resulted in the muddy water gushing inside and rapidly filling the aircraft. The passengers seated in the rear of the aircraft were unable to open the rear door. The water almost filled the entire cabin during this time.

The pilot was eventually able to get the rear door open from outside the aircraft and assisted some of the passengers out. The remaining passengers either made their own way out, or were assisted by other passengers.

One of the passengers sustained serious injuries, and the pilot and another passenger, minor injuries. The aircraft was almost completely submerged resulting in substantial damage (Figures 5 and 6).

Figure 5: Post accident showing VH-BDG partially submerged in the dam

Source: Airpark operator

Figure 6: VH-BDG after retrieval from the lake. Passenger 2 (below) reported that the left wing crumpled during the ‘cartwheeling’ toward the lake. Note:Significant damage occurred during the retrieval process

Source: Pilot

Pilot experience and comments

The pilot had approximately 581 total flying hours with about 112 of these on Cherokee Six type aircraft. The pilot made the following points:

• the hazard briefing conducted by the airpark operator some weeks earlier, included a request to land on the gravel area of the runway, as the seal was recently laid but had proved to be quite soft
• both weight and balance, and performance calculations were conducted for the flight, however these documents were damaged when the aircraft became submerged
• there may have been some wind shear or a down draft which contributed to the aircraft sinking on the approach
• the tail scraping along the gravel and over the fence during the attempted go-around added extra drag, which detracted from the aircraft’s performance

Passenger comments

Three of the five passengers elected to provide their accounts of what happened.

Passenger one recalled:

• there was no pre-flight safety briefing; the pilot just indicated where each of them should sit
• during the landing approach, this passenger recalled thinking how low they were, when still some distance from touchdown
• the tail struck the ground, and recalls power being applied after that
• the aircraft flipping over and ‘cartwheeling’ toward the lake

Passenger two recalled:

• there was no pre-flight safety briefing
• during the approach to land they heard the pilot verbalising that the aircraft needed to slow down, and noted a significant decrease in speed
• the aircraft tail dragging along the ground, and the pilot calling out for assistance
• the left wing striking the ground and instantly crumpling (Figure 6)
• the aircraft then ‘cartwheeled’ ending up in the lake
• the water rose quickly in the aircraft when the front door was opened, leaving a very small pocket of air for the rear passengers
• they were rescued by the pilot through the rear door

Passenger three recalled:

• there was no pre-flight safety briefing
• the aircraft struck the ground prior to the runway
• the pilot shouted for assistance as the aircraft “went out of control during the approach”
• the aircraft ‘cartwheeled’ before arriving in the dam

Meteorological data

The ATSB obtained the Bureau of Meteorology weather report for area 44 covering the time of the accident. Area 44 was in two divisions that day and the southern division, which applied to the area south of Proserpine, including Lakeside Airpark, forecast variable winds of about 10 knots.

Lakeside Airpark landing area

Lakeside Airpark Landing area was identified in Enroute Supplement Australia (ERSA) (28 May 2015 version) as “UNCR” meaning it is both uncertified and unregistered.

As per the requirement for operations at this aerodrome, the pilot sought prior permission to operate there and a briefing on local hazards from the aerodrome operator. This onsite briefing by the aerodrome operator pointed out local hazards such as the powerlines in the vicinity and the preferred protocol of taking-off on runway 04, and landing uphill on runway 22, wind permitting. There was no hazard map available as mentioned in the ERSA.

Advisory material

The Civil Aviation Advisory Publication (CAAP) 89O-1 (2) “Published aerodrome information and reporting changes (November 2000) is available on the CASA website. This publication provides advisory material for publishing aerodrome information and reporting changes in respect of both licenced and unlicensed aerodromes that are included in the (ERSA).

Unlicensed aerodromes:

Unlicensed aerodromes are not required, under the regulations, to provide aerodrome information to [Aeronautical Information Service] (AIS) or the [Civil Aviation Safety Authority] (CASA) and to have their aerodromes included in ERSA.

…unlicensed aerodromes may also be included in ERSA, on request of the aerodrome operators. However, the aerodrome information published will be of limited format, being of a non-operational nature…”

CASA is conducting a post-implementation review of CASR Part 139 – Aerodromes. As part of this project, this CAAP and other Part 139 CAAPs and ACs will be reviewed. Additionally, CASR Part 175, which regulates the publication of aeronautical information, commenced on 5 March 2015 and the contents of CAAP 89O-1 (2) will be reviewed, to be consistent with this new regulation.

ATSB comment

The ATSB did not undertake an onsite investigation into this accident, but were provided with information through telephone interviews, reports, and detailed photographs.

The ATSB was unable to reconcile the differences evident between the recollections of the pilot and those of the three passengers who provided information.

Safety message

This accident highlights the importance of thorough pre-flight planning and preparation to minimise safety critical decisions in flight.

CASA have an online kit "

” available from the downloaded from the CASA website.

This tool kit addresses the three levels of flight planning (the straightforward elements, unusual situations and whether to go) and their application over eight stages of flight.

The ATSB research report, Improving the odds: Trends in fatal and non-fatal accident in private flying operations(AR-2008-045) is available from the ATSB website.

This report encourages pilots to make decisions before the flight, continually assess the flight conditions, evaluate the effectiveness of their plans, set personal minimums, assess their fitness to fly, and to seek local knowledge (and if necessary a check flight) on the route and / or destination as part of the pre-flight planning process.

Also on the ATSB website, is a copy of the investigation (199804109) into a fatal accident involving another Cherokee Six aircraft (VH-POW). The pilot attempted to conduct a go-around from a degraded performance configuration with full flap extended and a nose-high attitude. The ATSB found that the aircraft's climb performance would have been substantially degraded with this configuration. The aircraft's nose-high attitude during the climb would have obstructed the pilot's forward vision and he may have been unaware that the aircraft had diverged from the extended centreline of the airstrip.

Aviation Short Investigations Bulletin Issue 44

Purpose of safety investigations The objective of a safety investigation is to enhance transport safety. This is done through: identifying safety issues and facilitating safety action to address those issues providing information about occurrences and their associated safety factors to facilitate learning within the transport industry. It is not a function of the ATSB to apportion blame or provide a means for determining liability. At the same time, an investigation report must include factual material of sufficient weight to support the analysis and findings. At all times the ATSB endeavours to balance the use of material that could imply adverse comment with the need to properly explain what happened, and why, in a fair and unbiased manner. The ATSB does not investigate for the purpose of taking administrative, regulatory or criminal action. Terminology An explanation of terminology used in ATSB investigation reports is available here. This includes terms such as occurrence, contributing factor, other factor that increased risk, and safety issue. Publishing information  Released in accordance with section 25 of the Transport Safety Investigation Act 2003 Published by: Australian Transport Safety Bureau © Commonwealth of Australia 2015 Ownership of intellectual property rights in this publication Unless otherwise noted, copyright (and any other intellectual property rights, if any) in this report publication is owned by the Commonwealth of Australia. Creative Commons licence With the exception of the Coat of Arms, ATSB logo, and photos and graphics in which a third party holds copyright, this publication is licensed under a Creative Commons Attribution 3.0 Australia licence. Creative Commons Attribution 3.0 Australia Licence is a standard form licence agreement that allows you to copy, distribute, transmit and adapt this publication provided that you attribute the work. The ATSB’s preference is that you attribute this publication (and any material sourced from it) using the following wording: Source: Australian Transport Safety Bureau Copyright in material obtained from other agencies, private individuals or organisations, belongs to those agencies, individuals or organisations. Where you wish to use their material, you will need to contact them directly.

The pilot joined the circuit on downwind leg for runway 27. The wind was observed on the windsock to be swinging from south through to southwest. It was reported as 180/11 on the ATIS. On short final, full flap was selected and the speed reduced to 65 knots. As the pilot initiated the flare the aircraft encountered a wind gust which displaced it to the right of the sealed runway.

The pilot recovered but then encountered another gust which caused the right wing to drop. He applied full power to go around and got the wings level, but the aircraft then hit the ground hard on all three wheels with full power still applied. The nosewheel dug into the dirt and broke off. The aircraft then nosed over onto its back.

Factors

The following factors were considered relevant to the development of the accident:

1. The aircraft was affected by significant wind gusts at a critical stage during landing.

2. The pilot was unable to recover the aircraft from the effects of the wind gusts.