Loss of control

History of the flight

The Lancair, registered VH-CIV, was a homebuilt aircraft operating under an experimental certificate of airworthiness. The owner had recently built the aircraft and had commenced a test flight program. The aircraft departed with a test pilot occupying the pilot seat, and the owner/builder occupying the right seat. Witnesses reported seeing the aircraft flying in the Drysdale area before descending steeply. It subsequently impacted the ground and the two occupants were fatally injured.

The pilot departed from Point Cook and flew along the coast, southwest of Point Cook aerodrome, at altitudes between 3,000 ft and 4,000 ft. After crossing Port Phillip Bay to the Bellarine Peninsula the pilot climbed the aircraft to between 5,000 ft and 6,000 ft. Recorded flight data indicated that the aircraft was slowed, and stalled at an altitude of 5,200 ft. The pilot recovered from the stall, but the aircraft entered another stall during the recovery at 4,950 ft. The pilot recovered the aircraft from that stall, and then repositioned it and entered a third stall at an altitude of 6,200 ft. The aircraft rolled at the initiation of the stall, and continued to roll as it then descended rapidly, accelerating to approximately 150 kts at an angle of approximately 40 degrees from the horizontal, with low engine power. The engine power increased shortly before the aircraft impacted the ground.

The aircraft impacted the ground upright, with the wings level, at a pitch angle of 40 degrees nose down. The landing gear was retracted at the time of impact, and the flaps were either completely or nearly retracted. There was no indication of any mechanical failure prior to impact. The accident was not survivable.

Flight crew

The pilot was an experienced ex-military pilot with 6,500 hours total aeronautical experience, including experience over many years in aircraft with a wide range of performances.

The owner/builder had a Commercial Pilot (Aeroplane) Licence issued 16 October 2001. He had 352 hours total aeronautical experience in a range of general aviation aircraft with a level of complexity and performance up to four-seat single-engine aircraft, with a constant speed propeller and retractable landing gear.

Aircraft

The aircraft was originally being constructed to comply with the requirements of Civil Aviation Safety Authority (CASA) Civil Aviation Order (CAO) 101.28. During construction, the experimental designation concept was developed and the aircraft construction was subsequently changed and completed in accordance with the experimental designation under Advisory Circular (AC) 21.4(2) issued September 2000. The certification requirements in the experimental category were less prescriptive than those in CAO 101.28 as experimental aircraft are not type-certificated. 'Experimental' is not a category but rather a designation. It is also important to note that an experimental certificate does not attest to an aircraft being fully airworthy (Civil Aviation Safety Authority Advisory Circular 21.1(1) - Aircraft Airworthiness Certification Categories and Designations Explained - Revised December 2000).

The aircraft was based on a Lancair IV-T kit plane that was originally designed to use a high-performance piston engine. The owner/builder decided to replace the engine with a turbo-propeller engine and sought assistance from a number of people to redesign the aircraft to accommodate the new engine.

Documentation indicated that during construction, numerous changes had been made to the original design, including the engine type and the design of the aircraft from the firewall forward. The propeller had been modified by removing 20 cm of the propeller tips. No evidence was found to indicate that any form of risk assessment had been undertaken to consider the safety implication of these aircraft design changes. A risk assessment was not required for aircraft constructed under the experimental designation.

Aircraft equipment

The aircraft was equipped with an integrated electronic flight information system (EFIS) comprised of a number of data acquisition units and three liquid crystal multi-function display (MFD) units, that could be configured to present operational information in different ways. The instrumentation system received data from a variety of sources, and integrated that data to present operational information to the pilot. Each MFD also contained a memory unit that recorded information that was sent to it. This information was used by the ATSB to determine the flight profile prior to the accident.

The MFDs could be selected by the pilot to display primary flight information, navigation information, or engine system information. The primary flight information consisted of an electronically generated artificial horizon display upon which a number of other information displays were overlayed. Indicated airspeed (IAS) was also displayed on the left side of this display. The IAS was presented as a vertical tape display of airspeed with a range of approximately 100 kts, in increments of 10 kts. The actual airspeed was also displayed numerically on the left side of the artificial horizon display, adjacent to the IAS speed tape display. The airspeed tape display contained a number of coloured regions to indicate various speed ranges and included the stall speed of the aircraft. The stall speed was dynamically generated and changed with varying flight loads on the aircraft. The displayed stall speed was known as the G-corrected stall speed. The EFIS derived the G-corrected stall speed from the aircraft's static 1G stall speed. The 1G stall speed had to be manually entered into the EFIS. The aircraft instrumentation system had been programmed with a 1G indicated stall speed of 69 kts with flaps and landing gear retracted.

The aircraft was also equipped with a video camera mounted on the ceiling just behind the two front seats, which was aimed at the instrument panel. This camera operated for some of the test flights, and some of the recordings were recovered from the camera after the accident.

The original aircraft design (with a piston engine) had a declared indicated stall speed of 84 mph, or 73 kts with flaps and landing gear retracted. The Comparative Aircraft Flight Efficiency (CAFE) foundation test flight of this version of the aircraft type recorded a stall speed of 78 kts with flaps and landing gear retracted. That test flight was conducted with a calibrated pitot/static boom, so the indicated airspeed would have been accurate in that instance. A theoretical aerodynamic calculation for the accident aircraft indicated a stall speed of 82 kts. Recorded information indicated that the aircraft stalled at 82 kts at the commencement of the accident sequence.

A flight path marker symbol, in the centre of the primary flight display, indicated the current pitch attitude of the aircraft. At an airspeed of 20 kts above the G-corrected stall speed, an amber pitch limit indicator symbol appeared above the flight path marker. The pitch limit indicator symbol moved down toward the flight path marker symbol as the airspeed decreased towards the stall speed. At 5 kts above the stall speed, the pitch limit indicator symbol turned red. At the point of stall, the pitch limit indicator symbol overlayed the flight path marker symbol. Coincident with the pitch limit indicator symbol changing to red, an aural annunciator would repeat a voice warning of 'stall' and a red stall flag symbol would display in the bottom left corner of the primary flight display.

The aircraft was also equipped with an angle of attack sensing device that used pressure information from two ports on the upper and lower sides of the left wingtip to derive the angle of attack. This instrument could have indicated when the aircraft was approaching a stall. The investigation did not determine if it had been calibrated before the accident flight.

During a test flight on 9 December 2002, the test pilot had decelerated the aircraft until it was approaching the stall as a part of the test flight program. Written records from that flight noted:

'A/c [aircraft] becomes laterally unstable below 80 Kts.'

Recorded flight data indicated that the aircraft stalled three times during this flight, from speeds of 72, 75 and 76 kts. The test pilot had also noted:

'Close to stall at 75 Kts with 10 [degrees] flap
Close to stall at 72 Kts with full flap'.

Video recordings from the flight indicated that the aircraft had stalled, and rolled 45 degrees to the left, and then 45 degrees to the right of horizontal during the recovery from the stall. Stalls were not a part of the test flight program for the flight.

Test program

A friend of the owner/builder developed a program for the flight testing of the aircraft. That program followed the guidelines in the Federal Aviation Administration (FAA) Advisory Circular 90-89A - Amateur-built Aircraft and Ultralight Test flighting Handbook. The CASA Advisory Circular 21.4(2) - Amateur Built Experimental Aircraft - Certification, advised that CASA:

'...most strongly urges [Amateur-built experimental aircraft builders] to make detailed reference to [this document], prior to their flight programs commencing, and [to] follow the guidance provided.' (section 14.4).

The test flight program was detailed, and was clearly developed in accordance with the recommendations of Advisory Circular 90-89A. Neither the advisory material, nor the test flight program considered action to be taken if aircraft handling or performance produced unexpected results.

CASA Advisory Circular 21.4(2) stated:

'14.5 Those undertaking test flight programs may also derive benefit in consulting the following additional references, as applicable to the class of aircraft involved:

'(a) CAA publication dated January 91, Flight Test Guide for Certification of CAO 101.28 Category Aeroplanes...'

This document recommended calibration of aircraft flight instruments, so that the limits of the flight envelope could be accurately determined. The test flight program for the accident aircraft did not include the in-flight calibration of aircraft flight instruments, including the airspeed indicator. Comparison of the recorded airspeed from the satellite navigation system, fitted to the aircraft as apart of the EFIS, with the recorded airspeed from the pitot/static system showed no inaccuracy in airspeed indication.

There was no evidence that any significant risk assessment was undertaken during construction of the aircraft and in the development of the test flight program. Such a risk assessment could have examined the planned activities and considered any potential hazards for their likely impact on the aircraft's safety during test flights.

The friend who developed the test program stated that he conducted the first two flights of the aircraft, but subsequently did not participate any further in the test program. Prior to those initial flights, he conducted an operational pre-flight briefing with the owner. These briefings included hazards and potential actions. The investigation did not determine whether the test pilot for the accident flight conducted similar operational pre-flight briefings for subsequent flights.

There was no evidence that any significant re-evaluation of risk was done during the subsequent conduct of the test flight program. Such a risk assessment process could have examined the results of test flights for hazards that became apparent from analysis of observations and data from each flight. This could have allowed for a considered assessment of any risk mitigators for their likely impact on the aircraft's safety during subsequent test flights, as the aircraft flight envelope was expanded. For example, if unexpected handling characteristics had been encountered during a stall sequence, then previously identified mitigation procedures, such as moving the centre of gravity forward, could have been considered.

Aircraft design

An aircraft operated as an experimental aircraft does not have to comply with any specific design. Builders may comply exactly with a design, or may deviate from that design as much as they wish, or may build an aircraft independent of any previously developed design.

If an aircraft is built mainly in accordance with an established design, but with some design differences, then it may perform differently from an aircraft built exactly in accordance with that established design. If design differences are incorporated one at a time, then it is possible to measure the effect of any single design difference. If many design differences are incorporated at one time, the effect of a single design difference on the behaviour of the aircraft may be impossible to predict due to the compounding effect of other incorporated design differences. The accident aircraft had been constructed with many differences compared with the original Lancair IV-T design.

Required persons on board during test flights

A CASA delegate had issued a special certificate of airworthiness authorising flight in accordance with the test flight program. The approval included operating limitations for the test flight program, such as geographical limitations, minimum weather conditions for flight and the maximum number of persons to be on board the aircraft.

Test flights are hazardous compared with normal flight. Accordingly, there is normally a requirement for only operational persons to be on board an aircraft during a test flight. The special certificate of airworthiness under which the accident flight was made stated 'Only personnel essential for the conduct of the testing may fly on board the aircraft. The carriage of passengers is prohibited.'

This aircraft type was normally flown as a single crew operation, and the cockpit of this aircraft was configured for single crew operation. There was no evidence that the test flighting required two persons on board.

The pilot hired the de Havilland DH82A Tiger Moth aircraft, registered VH-AJG, to undertake a local pleasure flight with a friend. The aircraft took off from a grassed area parallel to the Royal Australian Air Force (RAAF) base Williamtown's main runway between the eastern end of the runway and taxiway `A'. During the take-off, the aircraft was observed to veer right and strike and destroy two taxiway lights with the right wheel. The pilot continued the take-off and the aircraft departed the Williamtown circuit area at 1428 Eastern Summer Time.

Based on witness reports and radio transmissions by the pilot, the aircraft initially conducted a sightseeing flight over the coastal suburbs of Newcastle City. About 20 minutes after takeoff, the pilot broadcast that he was transiting north through the Williamtown Mandatory Broadcast Zone west of the coast. The aircraft subsequently joined the Williamtown circuit from the north at 1519. The actual flight profile and manoeuvres conducted during the flight are not known. Shortly after joining the circuit, the aircraft was observed to depart level flight and impact the ground approximately 2 km southwest of the Williamtown airport. Both occupants were fatally injured and there was no evidence of fire in flight or after the impact.

A helicopter with an instructor and student on board was in the circuit area, about 1.5 km behind the Tiger Moth. The helicopter was about 800 ft above ground level and maintaining approximately 60 kts. The helicopter crew estimated that the Tiger Moth was flying at the same speed and altitude. The helicopter's pilots reported observing the left wings fold up, the aircraft rotate and fall almost vertically in a steep nose-down attitude rotating only a couple of times before impacting the ground.

A witness on the ground reported observing the aircraft's right wings fold back, followed by the aircraft spinning or spiralling to the ground. Another witness reported seeing the right wings folding up, making the wings into an `L' shape and about a metre long silver pole flying up from the cockpit area. The aircraft then started turning to the right. None of the witnesses reported observing the aircraft changing altitude or commencing a turn prior to the loss of control.

Personnel information

The pilot held a valid Australian Special Pilot Licence and had accumulated 360.6 hours total of which 4.1 hours were on the Tiger Moth. The pilot's tail-wheel experience totalled 7.9 hours. He was endorsed on the type and flew earlier that day with an instructor. The accident flight was his first unsupervised flight on the type.

The Australian Special Pilot Licence authorises a pilot with a current overseas private or higher class of licence to undertake private flights in Australia. The pilot held a United Kingdom private licence. He held an Australian Class 2 (private) medical certificate valid until October 2005, issued by the Civil Aviation Safety Authority (CASA) on the basis of his United Kingdom medical. There was no evidence of any physiological condition affecting the pilot that may have contributed to the occurrence.

Operation and weather

The aircraft was operated by the RAAF Williamtown Flying Club located on the base and the accident flight was the aircraft's third flight of the day. The weather was reported to be fine with a light north-easterly breeze.

The aircraft and its history

The Tiger Moth was a fabric covered biplane aircraft with two open cockpits in tandem arrangement. The pilot sat in the rear cockpit. The truss type fuselage was made from steel tubes while the wings and tail surfaces were constructed from wood. The two-spar, single-bay wings were reinforced by a system of drag struts, drag and anti-drag wires. Each spar was made from a single piece of wood with a reinforcing doubler glued at the interplane strut attachment. The spars were fitted with metal fittings used to attach the wings to the fuselage and cabane centre section upper struts. The flying, landing and cabane wires, tie rods and interplane struts gave the wings the required rigidity.

The aircraft was stressed to withstand maximum loads of approximately 7.5g (acceleration due to earth gravity). Information from the manufacturer indicated that even with the reinforcing doubler delaminated and ineffective, the aircraft was designed to withstand manoeuvre loads of about 5g.

The aircraft was manufactured in 1942 and used by the RAAF until August 1947, when it was decommissioned and received civilian registration. The aircraft was substantially damaged during an accident in 1967. It was then dismantled and stored until 1988 when it was rebuilt and had since accumulated approximately 48.35 flying hours. The fuselage truss structure was repaired and an overhauled engine was installed. The aircraft was fitted with four wings and propeller of original manufacture. The previous history of the wings and the propeller could not be determined.

In November 2001, the left lower wing was damaged when the landing gear collapsed on landing in Newcastle after a ferry flight from Bankstown. A new wing was manufactured and fitted in December 2001. On 13 January 2002, the left lower wing contacted the ground while the aircraft taxied after a flight.

The aircraft was used to perform only limited aerobatic manoeuvrers such as barrel rolls, loops and stalls. A few steep turns and dives were performed during the flights on the morning of 16 February 2002.

The aircraft was maintained in accordance with the applicable and current maintenance requirements. The maintenance release was valid until 9 March 2002. Examination of maintenance documents indicated that all required maintenance had been carried out. The aircraft had no known maintenance deficiencies and was considered capable of normal operation prior to the accident.

Accident site and wreckage examination

The impact site was an area of dense undergrowth, tall grass and 10 to 12 m high trees. The ground was soft and waterlogged. The wreckage was contained within a small area at the foot of a tall tree, its distribution indicated that the aircraft impacted in a steep nose-down attitude while rotating to the left. The aircraft and its four wings were extensively damaged. The wing spars were splintered and broken at numerous locations. The right wings struck a tree during impact and their damage was significantly more severe than the damage sustained by the left wings.

With the exception of both propeller blades and parts of the right wing rear spar interplane struts, all aircraft components and extremities were accounted for at the accident site. The propeller boss that remained attached to the engine shaft was the only part of the propeller recovered. Propeller contact marks on the tree indicated that the propeller was rotating at the time of impact. A part of the missing interplane strut was found some six months after the accident approximately 73 m from the accident site.

Examination of the engine, systems and flight controls did not reveal any pre-impact defect that would have prevented them from normal operation. The left front and rear flying wires and the left cabane wire were severed in overload. There was no fuel remaining in the ruptured fuel tanks, but fuel was evident at the accident site.

Sections of the wing spars were examined by a timber specialist who concluded that the wood was of high quality and in good condition. It was free of decay and there was no evidence to indicate that a failure of the wood was a factor in the accident. Some blue colouring of wood was present in one laminate of the propeller boss, but there was no evidence to link this discolouration with failure of the propeller. The specialist reported that many of the wood failures, on the three wings of the original manufacture, were brash rather than splintering, indicating some embrittling associated with the age of the wood.

Adhesive failure

The specialist also reported that some laminated members on the three wings of the original manufacture and the propeller failed at the glue line rather than in the wood. The failure was due to the glue line being devoid of the adhering adhesive. The adhesive was identified as Casein. The specialist reported that the observed failure was typical of that of Casein that was exposed to attack by micro-organisms and that the attack was evident all over the glued area of the joint except on small areas close to the edges of the glued components. No delamination was observed on the new wing fitted in December 2001. This wing was manufactured using modern synthetic resin adhesive.

Casein is a milk-based glue that was particularly popular around the 1940s, when the three wings and the propeller were most likely manufactured. Since it contains protein, it could be subject to attack by micro-organisms and weakened if the moisture content of the wood and the adhesive is allowed to increase above a certain level. The Casein glued joints, however, do not degrade instantaneously when wet. The amount of degradation is proportional to the time the joint is allowed to remain moist.

The specialist advised that the attacks by micro-organisms occurs when the wood and adhesive moisture content is approximately 18% or greater. A moisture content of 18% could be achieved if the wood was exposed to a relative humidity of 85% or greater. While such humidity is experienced in tropical Australia, the average moisture content of the wood and the adhesive is not likely to reach this level due to lower values during various times of the day. The evidence, however, indicated that the glued joints were probably subjected to a number of periods when the moisture content was high, allowing micro-organisms to attack the adhesive. Such periods were further evidenced by the presence of corrosion around the nails, bolts and screws securing the joints.

However, the specialist concluded that there is little or no evidence indicating that any single glue failure may have resulted in a catastrophic failure of a major structural element of the aircraft or the propeller.

Propeller

The numbers stamped on the propeller boss were consistent with the propeller having been manufactured in the 1940s. The wooden propeller consisted of a number of laminates. After the propeller was manufactured, the centre part of each blade was wrapped with a layer of `Irish linen'. The entire propeller was then coated with a relatively thick coat of dark coloured cellulose-based paint.

The pilot of a Cessna 206 (C206), departed from Badu Island, Qld at about 1210 Eastern Standard Time (EST) on a positioning flight to Horn Island, Qld in accordance with the visual flight rules (VFR). The aircraft had an estimated fuel endurance of 270 minutes. The pilot, who was the sole occupant, had been tasked to conduct a charter flight from Horn Island at 1330 with passengers who were reported as arriving on a scheduled flight from Cairns.

At about 1221 the pilot broadcast on the Torres Mandatory Broadcast Zone (MBZ) frequency that he was over Wednesday Island and tracking for a 3 NM final approach to runway 26 at Horn Island. A short time later he broadcast that he was holding until the weather over the runway cleared. At about 1238 the pilots of two aircraft in the Bamaga area reported hearing a MAYDAY broadcast from the pilot of the C206 on the MBZ frequency. The pilot did not describe the nature of the emergency. Further efforts by the pilots operating in the Bamaga area to contact the pilot of the C206 were unsuccessful and they advised air traffic services of the MAYDAY they had heard on the MBZ frequency.

An air and sea search was commenced. Later that day floating debris, identified as belonging to the C206, was located. The recovered items included the left main wheel and landing gear leg, the nose wheel and part of the nose gear landing leg and a seat. The following day divers located the aircraft approximately 3 NM east of Horn Island in 7 m of water but the pilot was not found.

The aircraft was recovered from the sea floor where it had been submerged for just over two days. It had been extensively damaged by impact forces. The nature of the recovery process resulted in further disruption of the wreckage. The outer left wing, left aileron and the engine cowls were not recovered. Salt-water corrosion had affected many of the aircraft components. The flaps were found in the retracted position and damage to the propeller blades was consistent with low engine power at the time of impact. Damage was consistent with the aircraft having struck the water at a moderate to high speed in a nose-down, left wing low attitude. The collision with the water was not survivable.

Examination of the damaged gyroscopic flight instruments did not reveal any indication of pre-impact malfunction. The vacuum pump was found in good condition and capable of normal operation. Although the aircraft was equipped with appropriate instrumentation for flight in instrument meteorological conditions (IMC) it was maintained to the VFR standard, as appropriate to the category of operation. Maintenance requirements were certified as having been performed and no evidence was found to indicate that the aircraft was other than serviceable prior to the flight. Analysis of recorded audio data determined that engine operation was normal during the pilot's radio transmissions.

The pilot was reported to have obtained a forecast from Airservices electronic briefing facility using the company computer terminal at Badu Island. That forecast predicted north-westerly stream weather characteristic of conditions normally experienced during the wet season in the Torres Strait area between October and April. The terminal area forecast for Horn Island, valid from 0600 to 1800, indicated light showers of rain and a visibility greater than 10 km. Throughout the forecast period, a temporary deterioration in conditions (up to 60 minutes) was forecast due to thunderstorms, with visibility reduced to 2000 m in rain and a cloud base of 800 ft. Approximately 40 minutes before he departed Badu Island, the pilot received a telephone call from the senior base pilot. The senior base pilot had flown from Badu Island to Horn Island that morning and advised him of the actual weather conditions he had encountered, including 20 minutes holding east of Horn Island while awaiting a rain shower to move from over the aerodrome.

Witnesses reported that the weather conditions at Horn Island aerodrome between 1230 and 1245 were less than visual meteorological conditions. Heavy rain had reduced visibility to less than 100 m. One witness reported seeing lightning to the north of the aerodrome. A Bureau of Meteorology assessment of weather conditions for the area east of Horn Island at the time of the occurrence indicated that the generally low overcast cloud contained embedded thunderstorm cells, with associated heavy rain and a cloud base less than 1,000 ft. The recorded rainfall intensity was heaviest between 1230 and 1300. Weather conditions at Horn Island at the time of the occurrence were described by witnesses as being the most severe seen that season.

The pilot held a Commercial Pilot (Aeroplane) Licence and a valid Class 1 medical certificate. He had obtained his commercial pilot licence in September 2000 and qualified for a command multi-engine instrument rating in April 2001. The pilot's logbook was not found. A compilation of flight time records showed that at the time of the occurrence the pilot had between 270 and 290 hours total flying experience that included approximately 45 hours on type. The company did not require the pilot to maintain IFR currency there was no evidence that the pilot had met recency requirements for instrument flight. The pilot was not reported to be suffering from any physiological condition that may have affected his capability as a pilot. He had been off duty for the two days prior to commencing duty on the morning of the accident.

In July 2001 the pilot moved to the Torres Strait area and gained some occasional flying experience with another operator. In November 2001 the pilot commenced employment with the operator he was working for at the time of the accident as a VFR charter pilot on C182 and C206 aircraft. On 19 November 2001, before commencing operational duties, the pilot had flown a familiarisation flight under supervision of the senior base pilot. On 27 November he had demonstrated proficiency on the C182 in normal and emergency procedures to an approved company check pilot. That flight of one and a half hours also incorporated a short area familiarisation. The pilot was then certified as competent to conduct company charter flights. On 1 December 2001 he flew the C206 while acting in-command under the supervision of the senior base pilot.

The flight was being conducted under the VFR, at an altitude that required the aircraft to remain clear of cloud, and with a minimum flight visibility of 5,000 m. The operator's operations manual instructed pilots to consider uplifting additional fuel for diverting or holding when the forecast indicated elements of weather below the minimum required for the flight. The pilot had departed with ample fuel reserves for holding or diverting. Company pilots reported that diversions and holding, due to rain showers and associated poor visibility, were not unusual during the wet season. The pilot had broadcast his intention to hold until weather conditions improved.

Although the pilot of the C206 had flown in IMC during his training he did not have any instrument flight recency and had very little exposure to tropical wet season weather conditions and its characteristic heavy rain shower activity.

The circumstances of the occurrence were consistent with a loss of control at low level and at an altitude from which recovery was not considered possible. Due to the limited information available to the investigation, the reason for the loss of control could not be determined. However, the circumstances were consistent with VFR flight into IMC.