The crew on VH-EWA were conducting circuit training at Melbourne Airport. On the base leg turn for runway 34 the crew reported sighting another aircraft which had passed above them.

The other aircraft was VH-TXN, which had entered the Melbourne control zone without a clearance. The pilot of VH-TXN was proceeding from Tyabb to Shepparton and the pilot was intending to track around the southern and western boundaries of the zone. No contact was made with the aircraft until the pilot later called on the Radar Advisory Service (RAS) frequency at Rockbank.

Subsequently the aircraft again entered the zone without a clearance near Sunbury. The aircraft was not on the RAS frequency at the time. Subsequently RAS made radio contact, and the pilot was given radar headings to clear the zone near Beveridge.

Later checking of the plan for VH-TXN showed the pilot had made calculation errors in estimating the appropriate headings to fly and also errors in the time intervals. Enroute navigation errors also occurred.

Significant Factors

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

1. Poor flight planning by the pilot of VH-TXN.

2. Poor inflight navigation procedures by the pilot of VH-TXN.

While conducting solo circuit training at Broken Hill the student pilot made a bounced landing, then failed to apply sufficient back pressure on the control column as the aircraft touched down again.

The nose landing gear partially collapsed allowing the propeller to contact the runway. The pilot was not injured and later received additional dual circuit training from a club instructor.

The glider was being winch launched. On the initial climb at a height of about 300 feet the winch cable failed. The pilot made a modified circuit, with the base leg halfway along the strip. Touchdown was well into the strip. The pilot realised the glider would hit the fence at the end of the strip, so he attempted to lift it over the fence. The glider came down on top of the fence, catching the left wing. It then swung left, and the right wing hit a tree.

Significant Factors

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

1. Winch cable failure.

2. Insufficient altitude after the winch cable failure to ensure a successful circuit and landing.

Enroute from Curtain Springs to Alice Springs, while flying low and slow to observe cattle, the pilot heard a loud noise followed by an immediate increase in engine RPM and decrease in rotor RPM. An autorotational approach and landing was carried out into the rough hilly terrain, but the helicopter landed heavily and rolled over.

A subsequent investigation revealed that the clutch assembly upper bearing had failed allowing the engine drive to disconnect from the rotor system.

The bearing was a commercial bearing, not a genuine Robinson bearing, although the manufacturer's instructions clearly state that only genuine bearings, having the correct internal clearances, must be installed. A specialist report indicated that the failure was due to brinelling of the bearing races, possibly caused by the bearing being dropped or damaged during assembly of the clutch. There was also evidence that the bearing had not been sufficiently lubricated which would have decreased its time to failure.

Although the accident was survivable, severe spinal and lower back injuries were suffered by both occupants. It was reported that the space below the seats contained a number of hard items including a hand fuel pump. The flight manual for this type of helicopter, and placards placed near the under-seat compartments caution against placing hard objects in them as they could cause injury to occupants if the seats crush while absorbing energy during a heavy landing.

SAFETY ACTION

As a result of the investigation, the Civil Aviation Authority issued Airworthiness Directive AD/R-22/39, which requires an inspection of the upper clutch actuator bearing of all R22 helicopters to ensure only approved parts are fitted.

The aircraft taxied for departure to Sydney about 90 minutes behind schedule due to fog at Wagga. Although the First Officer was the handling pilot for the flight, the Captain taxied the aircraft as it was not fitted with dual nose wheel steering controls.

During taxi, the First Officer read the pre-take-off checklist. At the flight and navigation instruments check, he incorrectly read the outbound track from the flight plan as 118, which was the distance in nautical miles from Wagga to the TAPIO reporting point enroute to Sydney. The correct track was 053 degrees magnetic and as neither pilot had recognised the error, they set 118 on both HSI's.

After issuing an airways clearance for the aircraft to proceed to Sydney via Bindook at 9,000 ft, the Wagga tower controller cleared the aircraft to take-off on runway 05 and to make a right turn.

The First Officer assumed the handling pilot duties when the Captain handed over control of the aircraft during the take-off roll. The tower controller, who was monitoring the departure, said he lost sight of the aircraft due to low cloud while it was maintaining runway heading. Following a request from the tower controller the Captain advised that the cloud base was 1,000 ft above terrain. When the aircraft was established on the 118 radial of the Wagga VOR, the Captain passed the departure message. He advised the tower controller that the aircraft was tracking 053, which he read correctly from the flight plan, and was climbing to 9,000 ft.

At cruising altitude the aircraft was above two layers of cloud, through which the crew had occasional glimpses of the ground. About 10 minutes after departure the Captain decided to climb to FL 110 due to moderate turbulence, and to avoid cloud build-ups ahead. ATC requested the crew to squawk code 1000 with ident prior to issuing a clearance for the change of level. The aircraft was then located 70 NM to the right of the planned track, to the south west of Canberra. This error was subsequently recognised by the Captain who advised ATC. The aircraft was issued with a clearance to track via Canberra and Bindook to Sydney. There was no confliction with other IFR traffic.

Significant Factors

• The First Officer misread tracking information from the flight plan during the pre-take-off checks.
• Neither pilot verified the orientation of the selected track by reference to the appropriate map or chart.
• Weather conditions prevented the tower controller from adequately monitoring the aircraft's outbound track.

Two aircraft were flying in opposite directions on the track between Mackay and Clermont. The inbound aircraft to Mackay was being held at 5,000 ft until the outbound aircraft had passed. The outbound aircraft was maintaining 4,000 ft. The controller estimated that the two aircraft would pass at about 21 NM from Mackay.

The controller was using Distance Measuring Equipment (DME) reports from both aircraft to obtain the required separation before allowing further climb or descent. When the inbound aircraft reported at 20 DME, and the outbound aircraft reported at 25 DME, he allowed the inbound aircraft to descend. Just after passing 4,500 ft the pilot of the descending aircraft sighted the outbound aircraft straight ahead and slightly below. He took avoiding action and reported the event to ATC.

It was subsequently determined that the pilot of the outbound aircraft had not been trained in the use of DME, and that the equipment in the aircraft was unreliable. When asked for DME distances he had provided dead reckoning distances obtained by map reading, which were incorrect.

The pilot made the landing approach for runway 35, observing that the runway was clear. A normal touchdown was achieved just beyond the displaced threshold. On the ground roll at a speed of about 80 knots the aircraft struck a kangaroo that had just hopped onto the runway. The pilot saw it only for an instant before the collision. The nose wheel assembly collapsed as a result of the impact and the aircraft slid to a stop.

Significant Factor

The following factor was considered relevant to the development of the accident:

1. A kangaroo entered the runway.

The gliding club was conducting a ridge soaring camp remote from its main base of operation, but gliders launched that morning by aerotow were reporting poor lift conditions.

A glider released near the ridge just prior to the take-off of VH-IKA was finding it difficult to find any significant lift, and the pilot believed that they had released too early for the prevailing conditions. He saw VH-IKA release about 4-500 feet lower than he had and commented to his passenger that VH-IKA would have to out-land.

A short time later he saw VH-IKA tracking towards some suitable paddocks, but were over-flown, then after several left and right turns commenced a low approach to land in another paddock.

The paddock selected was lined by trees and powerlines, and as the approach was continued the left wing clipped a tree and the glider impacted the ground inverted. Both occupants were injured and the glider substantially damaged.

The occupant of the rear seat held a gliding instructor rating but was riding as a passenger on this flight. Although he realised that the approach was becoming low, he did not doubt that the experienced pilot could handle the situation and failed to take action to prevent the accident.

1. FACTUAL INFORMATION

1.1 The incident

The Airbus A300-B4 aircraft departed Sydney on a scheduled service to Brisbane. At about 700 ft after take-off the left engine fire warning activated. The crew carried out the appropriate procedures and shut down the left engine. With the engine shut down the fire warning indications ceased, therefore the fire bottle was not discharged. The aircraft was vectored for a priority landing back onto the departure runway and, after ground inspections confirmed the absence of fire, the aircraft was taxied to the terminal for a normal disembarkation.

Inspection of the engine disclosed a rupture of the 14th stage lower bleed air duct. Secondary thermal damage had occurred to the reverser cowl and minor mechanical damage was evident to the reverser mechanism.

1.2. Duct cracking

The engine manufacturer, General Electric (GE), advised that cracking can occur in the lower bleed air duct due to differences in thermal gradients. This occurs because the duct is made from a nickel alloy Inconel 625, and the support link assemblies are made of 321 stainless steel. Thermal stresses occur when the bleed air valve is closed resulting in the lower duct being cooler than the engine case. Installation stresses can also result in cracking.

1.3. Duct examination

The duct is a 90 mm pipe spanning approximately one-third of the circumference of the engine core. Three mounting lugs are welded to the outside surface of the pipe. The duct had ruptured around the toe of the weld at the lap joint of an end lug. Cracking was also present along the toe weld of the other end lug.

The fracture surfaces were subjected to both low power and scanning electron beam microscopy which revealed that the failure was typical of that due to fatigue. The fatigue had multiple initiations along both the outside and inside surfaces of the duct; however, the majority of the fracture had propagated from the outside surface. The fatigue fracture consisted of very fine evenly spaced fatigue striations typical of a constant amplitude load from the stresses associated with thermal cycles.

The fatigue extended around the end of the weld lap joint and approximately 30 mm each side of the lap joint before rapid tearing commenced. The fatigue fracture was stained indicating that hot air had been escaping for some time.

1.4 Propagation rate

The fatigue striation spacing was measured on a small area of fatigue fracture at various distances across the duct section from an origin on the outside surface to the boundary line between two areas of fatigue. From these measurements it was estimated that approximately 2,000 fatigue striations were present on this small area of fatigue fracture. Assuming that a thermal cycle is equivalent to an engine cycle, it would appear that this small area of fatigue had been propagating for 2,000 engine cycles. However, the entire fatigue fracture consisted of many fatigue cracks initiating at different stages during the life of the duct. This indicates that the fatigue cracking had been propagating for in excess of 2,000 engine cycles.

1.5 Recent inspections

The last maintenance inspection was during a Check "A" inspection carried out at 199 hours and 180 cycles prior to failure of the duct.  The last shop visit was 922 hours and 816 cycles prior to failure. The fatigue cracks were present, but not detected, when these inspections were carried out.

1.6 Operator's inspection requirements

The operator's inspection requirement was detailed on Task Card AB3-723300-0801-TN-L and R.  This task card is called up at each Check "A" inspection which at the time of the incident was on a rotating 320/480 hour schedule. The task was originally created on 29 October 1987. The task card in use during the last inspection of the duct was issued with an amendment dated 6 September 1990 which required:

"Visual inspection of high-pressure compressor emphasising......14th stage bleed air manifold for cracks".

This visual inspection was carried out at the last inspection but failed to detect the cracking.

1.7 Manufacturer’s requirement

GE issued Service Bulletin CF6-50-75-064 (SB 064) on 3 August 1990 to institute a recurring inspection aimed at detecting cracks in the 14th stage bleed air ducts.

On Page 4 of SB 064, at item 2.B was a requirement that a Spot Fluorescent Penetrant Inspection (SFPI) technique be used to detect cracks, with a requirement that the SFPI be carried out every 500 flight hours or 150 engine cycles whichever occurs last.

The operator's maintenance system is detailed in the Maintenance Instruction Manual (MIM). This manual sets out the procedures to be used to ensure compliance with the statutory requirements pertaining to engineering and maintenance activities.

Revisions to the MIM are accomplished by entering the necessary details onto a Manual Revision Authority form. The form is then processed in accordance with flow charts contained in the MIM. Some procedures are also contained within instructions raised within specific sections.

The preparation of the Manual Revision Authority form, the routeing through actioning sections, and the subsequent approval and incorporation of an amendment is accomplished by individuals actioning computer-based commands.

1.8 Operator's action

The operator received information, known generically as service literature, regarding introduction of the SFPI technique from both GE and Airbus Industrie (AI), the aircraft manufacturer.

Within the operator's maintenance organisation there are two sections which are required to process changes to maintenance requirements for engines. These are the Power Plant Engineering (PPE) section and the Maintenance Development (MD) section. There were at least four occasions when either or both sections assessed or reviewed the requirements of the SB.

These were:

(a) at initial issue of SB 064,

(b) on receipt of GE Commercial Engine Service Memorandum 76 (CESM 76)

(c) on receipt of an amendment to Airbus Industrie Maintenance Planning Document (MPD) dated October 1991.

(d) on receipt of an MPD amendment dated October 1992

1.9 Initial assessment of SB 064

GE issued SB 064 on 30 August 1990. Contrary to MIM requirements there were no entries made into the computer system that would have allowed the investigation to accurately track the initial routeing of SB 064.

The SB should have been received by PPE and passed to MD for assessment. The PPE engineer involved was no longer employed by the operator at the time of this investigation and was unable to be interviewed regarding his memory of his handling of the SB.

Available records do show that on 28 August 1990 an engineer in MD raised a Manual Revision Authority, numbered AB3100190, requesting the following change to the Maintenance Instruction Manual (MIM):

"Revise tasks AB3-723300-0801-TN-L & R to add visual inspections of the 8th and 14th stage bleed air manifolds". (BASI note - the terms manifold and duct are interchangeable).

The Purpose/Justification part of the Authority stated:

"New General Electric requirement as per SB 75-064".

This request for an MIM change was presented to, and authorised by, the Engineering Manager who did not identify that the assessing engineer in MD had made an incorrect assessment of the inspection process called up in the SB. As a result of the Engineering Manager's authorisation, the task card was amended on 6 September 1990.

MD also raised a Engineering Instruction (EI) numbered EI AB3-075-0102R00. The purpose of the EI is to notify other action sections of any change that may require their attention. This EI was not actioned because the assessing engineer, having raised the Manual Revision Authority, annotated on the EI that the SB was actioned by stating that the EI was "Terminated.... Covered By Maintenance A Checks".  There was no evidence of any communication taking place between PPE and MD prior to the decision to terminate the EI. However, anecdotal evidence suggests that there was often verbal communication between the sections regarding the processing of service literature.

The MIM did not require that a comparison between the SB inspection requirements and those contained in the Maintenance Check A been carried out prior to terminating the EI.

The MIM requires that PPE issue an Action Advice to notify MD that the intent of the SB is to be included in the applicable aircraft checks. An Action Advice covering the initial assessment of SB 064 could not be located.

1.10 General Electric Service Memorandum

On 10 September 1990 GE issued Revision 6 to Commercial Engine Service Memorandum (CESM) No. 76 which contained a consolidated listing of all scheduled inspection and servicing intervals for engines. This was received by PPE on 18 October 1990. PPE raised Action Advice number 9043002 on 1 November 1990 to notify MD of receipt of the CESM. MD assessed and cleared this Action Advice stating it was "Covered by AB3 MPD Revision".

While the statement is correct in that the task cards had been revised, the incorrect assessment and subsequent incorrect procedure were not identified by the person in MD responsible for carrying out the assessment of CESM No. 76.

1.11 AI MPD amendment dated October 1991

Airbus Industrie first introduced the requirement to comply with GE SB 064 via an amendment to the MPD issued in October 1991. The revised MPD was received by MD and assessed. The assessing/action engineer, while noting that GE SB 064 had been incorporated into the MIM via the task cards, did not identify that the original assessment had resulted in an incorrect procedure being called up.

1.12 AI MPD amendment dated October 1992

AI introduced a revision to the inspection intervals for GE SB 064 via a revision to the MPD issued on 30 October 1992.  Again, the MD assessing/action engineer while amending the inspection period did not identify that an incorrect procedure had been called up.

1.13 Operator’s review

When the MIM listing of an incorrect maintenance procedure became apparent the operator immediately established a review of the MIM amendment system. That review examined the procedures in use and checked that all mandatory inspections were correctly specified in the MIM.

The review found that:

(a) action Advice procedures were not being used consistently across all engineering groups;

(b) applicable service literature requirements had not been inserted into the system of maintenance;

(c) there was possible reliance on verbal communication in the service literature decision process;

(d) there was limited review of the service literature assessment by supervisors;

(e) there was a lack of discipline in checking that action data includes all necessary requirements;

(f) there was a breakdown of communication between and within PPE and MD sections;

(g) the review of the acquitted Action Advices appeared to be on an ad hoc basis; and

(h) there was no documented receipt, assessment and maintenance system revision procedure for introducing MPD amendments;

The review recommended that:

(a) members of engineering groups receive training in service literature handling.

(b) in regard to Action Advices:

(1) Ensure that the addressing reflects the current organisational structure.

(2) Ensure actions required to be taken by the addressee are detailed.

(3) Any response must be in a form that provides an audit trail.

(c) The decision process must not use verbal communication that may by-pass the computer-based recording procedure.

(d) A system of cross checking be introduced to ensure that service literature has been correctly interpreted and subsequent action is accurately presented.

(e) A formal procedure should be introduced to control receipt, assessment and revision certification for MPD amendments.

(f) Introduce a standalone listing of outstanding maintenance related Action Advices.

(g) Carry out a follow-up audit to establish that the recommendations are effective.

2. ANALYSIS

The system employed to receive, assess and incorporate service literature that requires an amendment to the MIM was basically sound. However, the system relied on each person correctly accomplishing a task, but did not specifically require the approving authority to check that the assessment was correct.

The operator’s review of handling of service literature found areas of non-conformance other than those which led to the development of the incident.

3. CONCLUSIONS

3.1 Findings

3.1.1 The manufacturer's requirement for an SFPI inspection of the duct was not included in the operator’s maintenance system.

3.1.2 Personnel who were required to action the documentation received from manufacturers did not follow established procedures.

3.1.3 There were inadequate safeguards in the system of maintenance to detect that established procedures had not been followed.

3.2 Significant factors

3.2.1 Visual inspections of the high-pressure duct did not disclose any evidence of cracking.

3.2.2 An SFPI inspection was not carried out because it was not called up on the relevant check sheet.

3.2.3 The check sheet had not been amended to include an SFPI inspection because of errors in transcribing the manufacturers requirement.

3.2.4 The errors in transcribing were not detected.

3.2.5 The high-pressure duct cracked and ejected hot air into the cowl area which activated the fire warning system.

4. SAFETY ACTION

4.1 The operator has instituted revised procedures that require the approving authority to check that the assessment details are correct.

4.2 The operator carried out a total review of the MPD to ensure that mandatory requirements were correctly assessed and that amendments to the MIM were correct.

4.3 The operator introduced a formal certification system that assures an audit trail of all service literature actions.

4.4 After the amendments to the system had been implemented the operator carried out an audit to ensure that the revised procedures were effective and were being complied with. This audit identified the need for a formal procedure covering the handling of Action Advices. This procedure is to be prepared and introduced on a priority basis.

The crew were carrying out a goat eradication program at the time of the accident. The aircraft was transiting from the hover to forward flight, at approximately 50 feet above ground level, when the engine suddenly stopped.

The pilot immediately entered autorotation and attempted to cushion the landing by increasing the collective pitch. The aircraft touched down heavily, tail first, before colliding with trees.

An inspection of the aircraft failed to disclose any reason for the sudden engine stoppage.

Weather conditions were conducive to the formation of carburettor ice however, the pilot had carburettor heat selected at the time of the accident.

The reason for the sudden stoppage could not be determined.