Collision with terrain

This occurrence was not the subject of an on-site investigation by the ATSB.

The Dromader aircraft was engaged in fire bombing operations in rugged terrain. Retardant carried in the Dromader's hopper was to be dropped on a fire, burning about half way up the eastern slope of a steep valley, oriented northwest to southeast. Before releasing the retardant, the pilot made a dummy run from the southeast to the northwest at a height of about 50 ft above the tree canopy. He then manoeuvred the aircraft onto a reciprocal heading for the drop run. Although that was in the direction of the head of the valley, the pilot's intention was to turn west into the valley after releasing the retardant.

The pilot reported that after releasing the retardant he applied full power and attempted to climb and turn, but found that the aircraft performance was less than that expected. He reported that when he attempted to bank the aircraft away from the side of the valley, the aircraft's performance diminished, depriving him of manoeuvrability. The pilot believed that he had encountered adverse windshear conditions in the lee of the ridge, associated with an active thunderstorm to the east of the ridge. Unable to turn away from terrain, the pilot maintained control of the aircraft but was flying toward the head of the valley. When he saw that a collision with trees was inevitable he transmitted on the dedicated communication frequency `I'm going in' and slowed the aircraft, allowing it to settle into the tree canopy. The aircraft collided with the foliage, pitched nose down and dropped to the ground in a near vertical attitude.

After ground impact, a fire started in the engine compartment and the pilot quickly egressed from the burning wreckage. The aircraft was destroyed by impact forces and the post impact fire. The plot reported that he had not detected any abnormality with the aircraft immediately prior to the accident.

Witnesses on the ground reported the presence of a thunderstorm on the other side of the ridge and occasional strong gusts of wind from the northeast. One witness reported seeing the aircraft wings roll to a "knife-edge" (90 degrees) attitude, then return to level just before the aircraft struck the tree canopy. The crew of an observation aircraft operating overhead the fire bombing activity, heard the pilot's transmission and watched as the Dromader impacted heavily timbered terrain below the top of the ridge. They also reported the presence of the nearby thunderstorm, northeast of the area. The crew of the observation aircraft reported that they did not encounter any significant turbulence or windshear at their altitude, about 1,500 ft above the Dromader.

The ATSB was unable to determine the exact circumstances of the accident. It was possible that the outflow of air from the thunderstorm, spilled over the ridge, creating down draughts that were in excess of the aircraft's climb performance, depriving the pilot of the manoeuvrability necessary for executing the intended flight path.

Abstract

On 7 February 2003, a Raytheon (Beech Aircraft Corporation) BE76 Duchess aircraft, registered VH-JWX, was being flown for the purpose of an initial-issue multi-engine command instrument rating flight test. A Civil Aviation Safety Authority (CASA) designated Approved Testing Officer (ATO), who was also the pilot in command of the flight, was to conduct the test. The other pilot was the flight test candidate who was flying in a 'dual' capacity because he was not yet qualified to conduct the flight. The candidate had to demonstrate to the ATO a number of manoeuvres in order to pass the flight test. Some of these manoeuvres included a demonstration of aircraft handling during a simulated engine failure. One manoeuvre required a demonstration of handling the aircraft when an engine failure was simulated during or after a take-off. The candidate reported that he and the ATO had agreed, prior to the flight, that simulated engine failures would not be conducted below a height of 500 ft above ground level (AGL).

The candidate had planned the flight to depart from Bankstown, NSW, and fly via Wollongong and Camden before returning to Bankstown. The planned departure time was 1915 Eastern Summer Time, however the aircraft did not depart Bankstown until 2038, which was 16 minutes after the end of daylight.

During interview, the candidate advised that they had conducted instrument airwork at Wollongong, including procedures with simulated engine failures, before they flew on to Camden.

At 2134, the candidate made two broadcasts on the Camden mandatory broadcast zone (MBZ) frequency, announcing that he was in the circuit area at Camden and intending to conduct an approach to runway 06 for a touch-and-go. Soon after take-off from the touch-and-go, a witness observed the aircraft flying at a low height and parallel to the runway, with the landing gear retracted. Another witness reported hearing two loud impacts. That witness observed that the aircraft had impacted the ground and had caught fire, beyond the departure end of the runway and to the right of the runway 06 extended centreline. The candidate and the ATO received severe burns as they evacuated the aircraft. The ATO died during the following morning.

The candidate stated during interview that, shortly after take-off from the touch-and-go, as he was handling the landing gear retraction switch, the ATO simulated a failure of the right engine. The candidate said that he continued to retract the landing gear and manoeuvred the aircraft to maximise its climb performance, but did not handle the engine controls. He reported that because the aircraft was not achieving satisfactory performance, he called for the ATO to apply full power. He said that soon after this call, there was a loud impact noise. Moments later, the aircraft collided with the ground.

An examination of the accident site revealed that the aircraft's right wing had contacted a large tree approximately 296 m beyond, and 133 m right of, the runway 06 extended centreline. The aircraft had climbed approximately 50 ft from where the witness saw the aircraft flying parallel to the runway to the point where the aircraft collided with the tree. The aircraft then appeared to have descended slightly into rising terrain, before it collided with the ground approximately 210 m beyond the tree. Score marks on the ground from the propellers and flaps indicated that the aircraft had impacted the ground at a high angle of attack, with both engines operating at a high power setting, and at a groundspeed of about 55 kts. The aircraft collided with steel and concrete structures as it slowed to a stop, however the cockpit area remained intact. Both wing fuel tanks were ruptured during the impact sequence and an intense post-impact fire erupted, consuming the cockpit area and right engine nacelle.

The weather was reported as being fine, with a light north-east wind and overcast cloud at 5,000 ft. Some illumination was provided by ground lighting from Sydney that was reflected from the base of the cloud.

The candidate reported that the aircraft had been operating normally throughout the flight. A post-accident review of medical history indicated that there were no physiological or psychological factors for either crewmember that may have affected the flight crew's performance prior to, or during the accident.

Aircraft performance

The Duchess was required under Civil Aviation Order 20.7.4 (8) to have a climb capability under defined conditions in the event of an engine failure¹. Typically, a light twin such as the Duchess loses much of its ability to climb with one engine inoperative, with the aircraft configured with the propeller of the inoperative engine feathered and the landing gear retracted. An aircraft's windmilling² propeller creates significantly more drag than a feathered propeller and, as a consequence, the Duchess would not have had the capability to accelerate or climb on one engine, with a windmilling propeller.

Night asymmetric flight

Asymmetric flight at night was not precluded by regulation. However, guidance provided to pilots contained in the Aeronautical Information Publication (AIP) stated that simulated asymmetric flight at night must not be conducted below 1,500 ft AGL. Civil Aviation Advisory Publication (CAAP) 5.23-1 (0) provided guidance on a syllabus of training, which included night asymmetric circuits. A note in that publication reminded the reader that the condition in AIP, which effectively precluded these operations from the circuit area at night, applied. However, no guidance was given on how to reconcile the conduct of asymmetric night circuit operations with the height limitation in AIP.

Previous accident review

A night asymmetric training accident involving a SA227-AC Metroliner, VH-NEJ, at Tamworth on 16 September 1995 (Occurrence report BO/199503057), was investigated by the then Bureau of Air Safety Investigation (BASI), which issued the following interim recommendation on 01 May 1996:

'IR 950224

The Bureau of Air Safety Investigation recommends that the Civil Aviation Safety Authority amend the Civil Aviation Regulations and the Civil Aviation Orders to ensure that when a provision of the Aeronautical Information Publication specifically prohibits certain manoeuvres and procedures, then this prohibition has legal force which is reflected in relevant Civil Aviation Regulations and Civil Aviation Orders.

The Bureau of Air Safety Investigation recommends that the Civil Aviation Safety Authority take appropriate steps to inform and educate the industry on the hazards involved in asymmetric training operations in conditions of low visibility and at night.'

The Civil Aviation Safety Authority responded to the recommendation 01 August 1996, stating:

'I refer to your interim recommendation IR950224 concerning the accident involving SA227 AC, VH NEJ at Tamworth on 16 September 1995. I apologise for the delay in forwarding the following comments.

The Regulatory Structure and Validation Project (RSVP), which is the first stage of a two-stage review of existing civil aviation regulations, is currently being finalised by CASA. The RSVP will, inter alia, rectify the problems identified in the first paragraph of the BASI recommendation. In addition, CASA endorses the recommendation in the second paragraph of IR950224 and will produce an article in the summer issue of the Flight Safety Australia magazine on the hazards of asymmetric training operations in conditions of low visibility and at night.'

Following the response from CASA, BASI classified the recommendation as 'Closed - Accepted'.

An article appeared in the March/April 2002 edition of Flight Safety Australia entitled 'Even Worse than the Real Thing'. Mention was made of performing the EFATO manoeuvre in visual flight conditions, but it did not emphasise the hazards of conducting 'engine failure after take-off' (EFATO) manoeuvres at night or night asymmetric training.

To date, the issue identified in the first paragraph of the Bureau's 1996 recommendation has not been rectified. Accordingly, the ATSB has amended the status of the recommendation to 'Monitor' pending evidence of the proposed action being taken by CASA.

Role and function of an Approved Testing Officer

The candidate was being tested for a flight qualification that is awarded and administered by CASA. CASA delegated the conduct of most flight tests to Approved Testing Officers (ATOs), who are authorised to conduct flight tests on behalf of CASA.

A flight test is used to demonstrate a pilot's competence in a particular aviation operating environment, to a defined level. Normally, a pilot is not qualified to conduct that type of flight until the flight test has been passed. The test officer is the competent pilot for the flight and is responsible for maintaining the safety of the flight.

A flight test explores the limits of the operating environment that is being examined, even though the limits of that environment will not normally be used while exercising the privileges of the qualification. For example, it is not normal to conduct asymmetric multi-engine operations, except during training, during a flight test, or in the event of an actual engine failure.

Categorisation of flight test operations

There are many similarities between flight training and flight test operations. In both cases:

• the pilot in command is responsible for the safety for the flight. However, the pilot in command does not normally manipulate the controls for most of the flight, although they are entitled to resume control of the aircraft to maintain the safety of the flight.
• the limits of a defined flight envelope are explored, to ensure that the student or candidate is capable of operating the aircraft safely throughout that defined envelope.
• the pilot in command is normally paid for his or her services.

Irrespective of any legislative or regulatory requirement, the nature of both types of operation, and the risks associated with both types of operation are very similar. If a similar risk level is to be expected from both types of operation, it would be reasonable to expect similar defences against those risks to exist in both types of operation.

Unlike formal flight training, flight tests conducted by ATOs were not prescribed as commercial operations. Civil Aviation Regulations (CAR) did not define flight tests as private operations, however they generally referred to private operations as operations in which the operating crew received no remuneration for the flight. In accordance with standard practice, the candidate and the ATO had made a commercial arrangement in that the candidate was to pay the ATO a fee for his flight test services.

A commercial flight operation, as defined under Civil Aviation Regulations³, had to be conducted under the management of a commercial air operator whose activities had to be managed, and the management process had to be approved and monitored by CASA.

Commercial operators who are required, under CAR (1988) 217, to conduct training and checking also conduct similar types of flight test. Those organisations are required to conduct this type of flight test in accordance with the requirements of an Air Operator's Certificate and the Check and Training procedures appended to that Air Operator's Certificate. This provides the opportunity for CASA to authorise the testing process and to ensure that procedures for risk mitigators, such as minimum operating altitudes, are formally maintained. There were no such requirements for flight tests conducted as private flights.

CASA provided guidance to ATOs on the conduct of flight tests in the form of a 'Flight Crew Licensing Industry Delegate's Handbook'. This document described the procedures surrounding a flight test and defined what was to be tested. The handbook did not provide guidance on the conduct or management of a flight test, or the precautions necessary to ensure the safety of a flight test.

Analysis

The ATO commenced a simulated engine-failure exercise from a position where a subsequent safe flightpath could not be assured. The aircraft deviated from the extended runway centreline track and collided with a tree. The ATO and candidate were not able to ensure that the likely flightpath was free from obstacles, so the safety of the flight could not be assured following a simulated engine-failure from this position in the flight. The aircraft's flightpath and normal operating procedures for a simulated engine-failure exercise make it likely that an engine failure was simulated, and then full power was returned to that engine without that propeller being feathered, or any other power adjustments being made.

A flight test is used to examine a pilot's competence throughout a flight envelope that is defined by the requirements for the flight test. A flight test will therefore normally operate nearer the edges of its defined flight envelope than other types of flight. The test officer is the competent pilot on board, and is therefore responsible for the safe operation of the aircraft. The safety buffer inherent from operating within a defined flight environment does not exist when a flight operates outside that environment. That was no different from the flight training regime where an instructor and student are performing the same manoeuvre.

The candidate pilot, who had not yet been deemed competent to fly in the defined flight envelope for the flight test, would normally be the handling pilot. The test officer would therefore be responsible for the safety of a flight being flown by a pilot who might not be competent, while operating at the edge of the defined safe envelope. These conditions remove some of the inherent defences that would make a normal flight safer. This higher risk situation is necessary for the effective conduct of a flight test. In the case of a multi-engine command instrument rating flight test, any abnormal operation of the aircraft, such as asymmetric flight therefore has an element of risk not present in normal operations. Setting safe speed margins and imposing altitude restrictions for the conduct of simulated emergency manoeuvres can mitigate that risk. Using experienced pilots as Approved Test Officers may also mitigate that risk.

Asymmetric flight with one engine failed degrades this aircraft type's ability to climb to a negligible quantity under optimal conditions. It is also normal to expect a minor change in direction as a change to an asymmetric condition is managed. This change in the aircraft's flightpath from two-engine flight to asymmetric flight should be taken into consideration when planning and managing asymmetric flight.

Planned low-level asymmetric flight at night is considered to be an unacceptable risk because, unlike daylight conditions, the pilot may neither know about, nor be able to see, any obstacles in the aircraft's changed flight path in order to take avoiding action.

The flight was a commercial operation, in that the ATO was entitled to charge for his services for the flight test, in the same way that a student pays for the services of a flight instructor when being trained. Because the operation was conducted as a private flight, it did not have similar risk mitigators that are inherent in the required organisational structure for a commercial flight, as happens with flight tests conducted through a Civil Aviation Regulations (1988), Regulation 217 (CAR 217) approved organisation. The ATO was conducting a flight test in accordance with the test requirements set by the CASA, and while acting as a delegate of the authority. CASA provided neither guidance nor prescriptive requirements to ATOs to ensure the consistent, safe conduct of flight tests.

Safety margins for the conduct of multi-engine instrument renewal flight tests are prescribed in the approved training manuals of training and checking organisations. However, when such a flight test is performed outside the oversight of a CAR 217 training and checking organisation, the safety margins can only be determined by the testing pilot and may vary depending on the experience and competency of both the testing pilot and the candidate. This means that the safety standards for the conduct of these flight tests are not consistent across Australian civil aviation.

This was the ATO's first flight with the candidate. Although some asymmetric flying was reported to have been performed earlier in the flight, it was possible that the ATO had determined that the candidate was capable of handling a simulated engine failure just after take-off from runway 06 at Camden. The simulated engine failure was contrary to the preflight briefing and may have been initiated at that point to negate the candidate's anticipation of a predetermined simulated engine failure at the briefed altitude.

The maximum groundspeed at impact was determined to be about 55 kts. In the light wind conditions at the time, the airspeed would have been approximately 60 kts, slightly above the aircraft's stalling speed in that configuration. It is unlikely that the aircraft would have been able to climb or accelerate significantly with only one engine operating while the landing gear was still retracting and the right propeller was windmilling.

The ATO was responsible for the safety of the flight. That responsibility included ensuring that the speed and altitude at which simulated emergency procedures were initiated provided adequate safety margins for the manoeuvres being attempted. The simulated engine failure just after take-off did not provide those adequate margins, especially at night, with inadequate visual reference to ensure obstacle clearance. It was likely that the ATO may not have been aware that the aircraft was not climbing and had drifted well right of the runway toward obstacles and higher ground. Although he reapplied full power to the simulated 'failed' engine at either the candidate's expressed concern or out of his own concern, the response was not timely enough to avoid a collision with the tree or the ground.

The risks associated with low level asymmetric operations at night were identified and addressed in May 1996 in Interim Recommendation IR19950224. Regulatory and education action that was addressed by CASA in its response to the recommendation in August 1996 has yet to be fully implemented.

Significant Factors

A simulated engine failure was initiated from a point where a safe outcome could not be assured.

Safety Action

CASA safety action

CASA is involved in a regulatory reform programme and is leading the development of new regulations which are proposed to be made by government. Some of those proposed regulations, as detailed below, impose new requirements on persons conducting flight tests.

The proposed new Civil Aviation Safety Regulations 1998, Part 91.305, is expected to incorporate a requirement that no planned asymmetric operations are initiated below the circuit height or 1,000 ft above the ground at night, or below a minimum en-route altitude or instrument initial approach altitude in instrument meteorological conditions.

The proposed new Civil Aviation Safety Regulations 1998, Part 61.220, is expected to change the conditions under which flight tests may be carried out. The present draft will require flight tests conducted by 'flight examiners' (those who conduct flight tests) to be booked through a flying training organisation, and that flight examiners must comply with the manual of standards (MOS) associated with Part 61. This MOS will specify what is to be assessed in each type of flight test, and will also specify that other things are not to be tested during the flight test.

The proposed new Civil Aviation Safety Regulations 1998, Part 141, is expected to require the operator to specify through their operations manual the procedures for the conduct of flight tests, and the responsibilities of the flight examiner for the safety of operations during the flight test. These procedures in the operations manual are expected to include the operator's specific requirements and methods for simulating emergencies and the evolutions necessary for the conduct of specific flight tests. Operators will need to be able to demonstrate to CASA that they are operating in compliance with their operating manual.

1 In order to operate under Instrument Flight Rules (IFR), this aircraft type was required to have demonstrated that it could climb at a 1% gradient with its critical engine inoperative, at an altitude of 5,000 ft in an International Standard Atmosphere (ISA). This equated to an indicated altitude of 5,000 ft on an altimeter with a subscale setting of 1013.25 hPa, and an atmospheric temperature of +5C.
2 'Windmilling' is the term used to describe a rotating propeller being driven by the airflow rather than by engine power.
3 Civil Aviation Regulations 1988, regulation 206 defined categories of commercial flight operations.

Related Documents: | Media Release |

Local safety action

The operator has amended the company's operations manual to correctly reflect the types of fire buckets used on the company's individual helicopter types.

The operator has standardised the position of the external load jettison switch on the different helicopter types used by the company in fire fighting operations.

The company's operations manual now details the type of safety clothing to be worn by pilots when engaged in water-bombing operations in company helicopters. The clothing specified includes the wearing of cotton or better, flying suits, approved helmets and comfortable fitting life jackets. Inflatable life jackets have been positioned in each helicopter for that purpose.

The operator has introduced a system for tracking the fitment and maintenance history of cargo hooks fitted to company helicopters.

ATSB safety action

In a briefing to the Civil Aviation Safety Authority, the ATSB drew attention to the fact that the occurrence bucket was not of standard manufacture, and highlighted the possible effects of the use of non-standard buckets by helicopters during fire fighting operations.

As a result of this occurrence, the Australian Transport Safety Bureau issues the following safety recommendations:

Recommendation R20030219

The Australian Transport Safety Bureau recommends that the Civil Aviation Safety Authority, in conjunction with the relevant industry associations, highlight the safety benefits to helicopter pilots and crew of the wearing of personal protective equipment, such as helmets and personal flotation devices when carrying out water-bombing in support of fire fighting operations, through safety promotion initiatives.

Recommendation R20030220

The Australian Transport Safety Bureau recommends that the Civil Aviation Safety Authority, in conjunction with the relevant industry associations, assess the desirability of a requirement for Helicopter Underwater Escape Training for specialist aerial work operations, such as water-bombing in support of fire fighting operations.

Recommendation R20030221

The Australian Transport Safety Bureau recommends that the Civil Aviation Safety Authority, in conjunction with the relevant industry associations, consider advising Australian helicopter operators involved in water-bombing in support of fire fighting operations, of the need to review the type of fire-buckets used to ensure that they comply with the bucket manufacturer's guidance for use on helicopter types and to ensure that the fire-buckets are appropriately maintained.

¹ Issue Date: January 2003.
² Issue Date: May 2002.

Related Documents: | Media Alert |

1. The weather conditions at the time of the accident were favourable to the development of lee waves and strong downslope winds in the vicinity of the airstrip.
2. The aircraft banked steeply out of wind, while at low airspeed and a low height.
3. The aircraft stalled at an altitude from which recovery by the pilot was not considered possible and control of the aircraft was lost.

At about 1708 Eastern Standard Time (EST) on 26 September 2002, the pilot of a Piper PA-32-300 (Cherokee Six) aircraft, registered VH-MAR, reported taxiing for departure from runway 14 at Hamilton Island, Queensland. The charter flight was to Lindeman Island, a distance of about 15 km to the southeast. On board the aircraft were the pilot and five passengers.

Witnesses to the east of runway 14 at Hamilton Island reported that, shortly after the aircraft became airborne, the engine began coughing and misfiring, before cutting out and then starting again. Shortly after, the aircraft commenced a right turn, and the engine was heard spluttering and misfiring. Witnesses reported that, when part way around the turn, the engine again cut out, and the aircraft descended and impacted the ground.

The aircraft came to rest upright, aligned in an east-north-easterly direction, approximately 300 m to the west of the runway centreline and approximately 100 m south of the departure end of the runway. A severe post-impact fire consumed the majority of the aircrafts fuselage. The six occupants of the aircraft were fatally injured.

The pilot was qualified, appropriately endorsed and authorised for the operation. The pilots condition and demeanour on the day of the occurrence were reported to be normal.

There was no evidence that fuel contamination, amount of fuel carried, structural failure or meteorological conditions were factors in the occurrence.

The engine installed in the aircraft was different from that specified in the aircraft Type Certificate Data Sheet. Notwithstanding, the Civil Aviation Safety Authority (CASA) and the engine manufacturer reported that the installed engine should have been capable of producing the power output expected from the engine certified for installation in the Cherokee Six. Furthermore, the engine had been in service in the aircraft for 126.2 flight hours with no reported power abnormalities, suggesting that, provided there were no defects, the engine should have been capable of producing the required power throughout its operating range.

The extensive damage caused by the impact forces and post-impact fire prevented functional testing of a significant number of aircraft and engine components. On the available evidence, there was nothing found to suggest what may have degraded the engine performance to the extent reported by the witnesses to the occurrence.

Post-mortem toxicological examination of the pilots blood revealed a blood alcohol concentration (BAC) of 0.081%, the presence of an inactive metabolite of cannabis, and an analgesic preparation consistent with a therapeutic dosage. The possibility that the pilots BAC reading resulted at least in part from post-mortem alcohol production could not be discounted.

There was insufficient evidence to definitively link the pilots prior intake of alcohol and/or cannabis with the occurrence. However, the adverse effects on pilot performance of post-alcohol impairment, recent cannabis use and fatigue could not be discounted as contributory factors to the occurrence. In particular, the possibility that the pilot experienced some degree of spatial disorientation during the turn as a combined result of the manoeuvre, associated head movements and alcohol-induced balance dysfunction could not be discounted.

The following factors were considered to have significantly contributed to the occurrence.

1. Based on witness reports, the aircrafts engine commenced to operate abnormally shortly after lift off from the runway.
2. The pilot initiated a steepening right turn at low level.
3. The aircraft stalled at a height from which the pilot was unable to effect recovery.

The operator has initiated a number of safety actions in order to mitigate some of the issues identified in the report. Those actions include the areas of: company pilot training, fatigue management, documentation, and aircraft operations.

The ATSB has issued four recommendations concurrent with the release of this report. The first three recommendations address the potential use of alcohol and drugs by safety-sensitive personnel in the Australian aviation industry, and options to manage the safety risk to the travelling public of that potential use. The fourth recommendation addresses the CASA Air Operator Certificate Safety Trend Indicator surveillance methodology. In addition, two Safety Advisory Notices have been issued to CASA relating to pilot manipulation of the Cherokee Six fuel selector and development by operators of pilot induction training programs.

FACTUAL INFORMATION

In common with most transport accidents, this occurrence involved a number of different contributing factors. Although some of these factors were associated with actions of individuals or organisations, it is essential to note that the key objective of an ATSB safety investigation is to identify safety deficiencies or weaknesses in the safety system and to learn how to minimise the risk of future accidents. It is not the purpose or intention of the investigation to apportion blame, or to provide a means of determining liability.

Sequence of events

At about 0836 Eastern Standard Time on 27 November 2001, a Beech Aircraft Corporation King Air C90 aircraft, registered VH-LQH, took off from runway 29 at Toowoomba aerodrome, Queensland for an Instrument Flight Rules charter flight to Goondiwindi, Queensland. On board were the pilot and three passengers.

Just prior to, or at about the time the aircraft became airborne, the left engine failed. A subsequent examination of the left engine found that it probably lost thrust-producing power almost immediately. Following the engine failure, the take-off manoeuvre continued and the aircraft became airborne prior to crashing.

The aircraft was equipped with an automatic propeller feathering system, but the propeller was not feathered at impact. The reason the propeller was not feathered could not be determined. The landing gear was not retracted during the short flight. The right engine was developing significant power at impact.

The aircraft remained airborne for about 20 seconds. The aircraft's flight path was typical of an asymmetric, low speed flight situation, and it is unlikely that the aircraft's speed was ever significantly above the minimum control speed (V_mca) of 90 kts. The aircraft manufacturer's specified procedures for responding to an engine failure in LQH stated that the take off should be rejected below the 'take-off speed', specified as 100 kts. After control of the aircraft was lost, and as the aircraft was rolling through about 90 degrees left bank, it struck powerlines about 10 m above ground level and about 560 m beyond the end of the runway. It then continued to roll left and impacted the ground inverted in a steep nose-low attitude. An intense fuel-fed fire erupted upon initial impact with the ground. The aircraft was destroyed and all four occupants sustained fatal injuries. The accident was not considered to be survivable due to the impact forces and post-impact fire.

Maintenance-related issues

The central event in this accident was the failure of the left engine, which was the 'critical' engine on the aircraft in terms of aircraft performance considerations. Examination of the left engine showed internal damage that was consistent with the fracture and release of one or more compressor turbine blades into the engine gas path, resulting in a significant reduction in power from the engine. There were no indications that the engine failure was due to manufacturing defects, metal fatigue, foreign object damage during the flight, or the quality or quantity of fuel on board the aircraft. Examination of the compressor turbine blades indicated that they had been exposed to higher than normal operating temperatures in the period leading up to the accident.

The engine failure occurred at 3,556.0 hours since the last overhaul, which was within the 3,600 hours time between overhaul (TBO) specified in the engine manufacturer's service bulletins. However, the aircraft's engines were operating on a life extension to 5,000 hours TBO in accordance with the provisions of the Australian Civil Aviation Safety Authority (CASA) Airworthiness Directive AD/ENG/5 Amendment 7. A requirement of the AD was that, if the engines were operating to a 5,000 hour TBO, they had to be subject to an engine condition trend monitoring (ECTM) program. The pattern of ECTM data from the left engine indicated that a potentially safety-critical problem existed in that engine for several weeks prior to the accident. For a variety of reasons, that evidence was not detected and analysed, nor was appropriate remedial action initiated. Without timely intervention to address the developing engine problem, it was increasingly probable that the aircraft would have an in-flight emergency involving the left engine.

The pattern of evidence suggested that a problem with the efficiency of the cold section of the engine probably led to temperature-related damage to the compressor turbine blades, which probably resulted in the failure of one of those blades. However, some other explanations for the failure, such as a previous hot start leading to or exacerbating the temperature-related damage, could not be discounted.

Apart from issues associated with the left engine, there was no indication of any fault in any aircraft system that may have contributed to the accident. The ECTM data for the right engine suggested that a potential problem had also been developing in the cold section of that engine for a period of time.

The last maintenance of the left engine most probably occurred on 7 June 2001. Based on the requirements of AD/ENG/5, a compressor performance recovery wash was required to be conducted in response to trend monitoring parameter deviations, or at intervals not to exceed 3 months or 220 hours, whichever came first. Had the performance recovery wash been conducted on the left engine at the appropriate time, it may have been effective in removing the source of deterioration in cold section efficiency.

Prior to March 2001, maintenance on the operator's aircraft was conducted by an external maintenance organisation. From March 2001, maintenance was conducted by a newly formed internal maintenance organisation. The ratio of the operator's available maintenance personnel resources relative to the maintenance resources reasonably required, resulted in the operator's chief engineer experiencing a significant workload. In August 2001, the maintenance controller left the operator and the chief engineer took over the maintenance controller responsibilities. His workload increased significantly when he took on these additional responsibilities.

In addition to the level of maintenance resources, the investigation noted that the defences within the operator's maintenance organisation were deficient in a number of other areas. The chief engineer had minimal preparation for his role as maintenance controller. He had also not completed ECTM training, and therefore the operator arranged to send the data to the engine manufacturer's field representative for analysis. However, the ECTM data were not being recorded or submitted for analysis as frequently as required by the engine manufacturer's requirements or AD/ENG/5. In addition, there were deficiencies in the operator's maintenance scheduling processes.

CASA was aware that the chief engineer had not completed ECTM training and that the operator had an arrangement to send ECTM data to the engine manufacturer's field representative for analysis. However, CASA surveillance had not detected any problems with the operator's ECTM program prior to the accident. Following the accident, CASA inspectors conducted a review of the engine condition monitoring programs of operators in their region. The review found that a number of the operators were not complying with relevant requirements.

The introduction of AD/ENG/5 allowed life extensions to be approved for PT6A engines in Australia under less restrictive circumstances compared with those required by the engine manufacturer. By allowing a wider range of operators to extend TBOs, there was an onus on CASA to take measures to assure itself, during its surveillance activities, that operators were complying with the AD and conducting ECTM appropriately. However, CASA's surveillance system was not sufficiently rigorous to ensure that the mitigators it had introduced within AD/ENG/5 for allowing TBO extensions were effective.

The investigation also noted that the CASA system for approving maintenance organisations and maintenance controllers did not appropriately consider the maintenance organisation's resource requirements.

Flight operations issues

The investigation determined that the pilot was appropriately licensed to conduct the flight, and that it was unlikely that any medical or physiological factor's adversely affected the pilot's performance. There was also no evidence that incorrect aircraft loading or meteorological conditions were factors in the accident.

Several factors would have contributed to the aircraft's speed not being sufficient for the pilot to maintain control of the aircraft during the accident flight. These factors included the significant loss of power from the left engine just prior to, or at about the time, the aircraft became airborne, and the substantial aerodynamic drag resulting from the landing gear remaining extended and the left propeller not being feathered. In addition, the aircraft's speed when it became airborne was probably close to V_mca and not sufficient to allow the aircraft to accelerate to the best one-engine inoperative rate-of-climb speed (V_yse) of 107 kts with an engine failure.

With an engine failure or malfunction near V_mca, the safest course of action would be to reject the takeoff due to the likelihood of the aircraft not being able to accelerate to V_yse. Although in some cases this will mean that the aircraft will overrun the runway and perhaps sustain substantial damage, the consequences associated with such an accident will generally be less serious than a loss of control after becoming airborne.

In this case, the engine failure occurred during a critical phase of flight, in a situation that was among the most difficult for a pilot to respond to in a manner that would ensure a safe outcome. In addition to the timing of the engine failure, a number of factors could have influenced the pilot's decision to continue with the takeoff, including the nature of the operator's procedures, the length of the runway, and the visual appearance of the runway and buildings beyond the runway at the time of the engine failure.

The operator specified a rotation speed of 90 kts, which was less than the 96 kts rotation speed specified by the aircraft manufacturer for King Air C90 aircraft. The operator's specified rotation speed had the effect of degrading the one-engine inoperative performance capability of the aircraft during takeoff. In addition, the operator's procedures did not provide appropriate guidance for pilots regarding decision speeds or decision points to use for an engine failure during takeoff.

While aircraft manufacturers have provided guidance material in operating manuals regarding engine failures leading to power loss in multi-engine aircraft, CASA had not published formal guidance material. The level of training available for emergencies in this category of aircraft during critical phases of flight and at high aircraft weights was less than desirable.

Toowoomba aerodrome was licensed and met the relevant CASA standards. However, runway 29 did not meet the ICAO standard in relation to the runway end safety area (RESA).

Safety action

Since the accident, CASA has made changes to the requirements of AD/ENG/5 and the processes for assessing the suitability of maintenance controllers.

As a result of this investigation, the ATSB issued six recommendations to CASA relating to the following areas:

• reviewing operator compliance with the requirements of mandatory turbine engine condition monitoring programs.
• surveillance processes for confirming operator compliance with mandatory engine condition monitoring programs.
• processes for identifying priority areas for consideration during airworthiness surveillance and approval activities.
• processes to assess whether a maintenance organisation has adequate resources to conduct its required activities.
• the provision of formal advisory material to operators and pilots about managing engine failures and other emergencies during takeoff.
• the assessment of synthetic training devices for the purpose of training pilots in making decisions regarding emergencies during critical stages of flight.

As a result of this accident, the ATSB has issued a recommendation to the aerodrome operator for it to liaise with CASA to evaluate an engineering solution to enhance aircraft deceleration in the runway end safety area of runway 11/29 at Toowoomba aerodrome.

A number of issues identified during the investigation related to the aircraft operator, and would normally have resulted in safety recommendations to that organisation. However, subsequent to the accident the operator ceased operations.