Engine failure and collision with terrain involving Jodel D11 VH-WBL 34 km north-north-west of Mackay Airport, Queensland

Overview of the investigation

The occurrence

On 24 December 2021, the ATSB commenced a transport safety investigation into a fatal accident involving an amateur-built Jodel D11 aircraft, registered VH-WBL, at Ball Bay about 34 km north‑north-west of Mackay Airport, Queensland, on the same day.

At about 0740 Eastern Standard Time,^[1] the pilot reported starting the aircraft at the Ball Bay airstrip and conducting engine run-ups before the passenger boarded for a private pleasure flight. After the passenger boarded, the pilot taxied the aircraft to the northern end of the runway and conducted a second engine run-up and magneto check, with no anomalies detected. The aircraft was then lined up for a take-off towards the south-east. The ground run and take‑off were uneventful until the aircraft reached a height of about 60 ft, when the engine started to intermittently cut-out. The pilot ‘pumped’ the throttle lever. However, the engine failed and power could not be restored. As there was insufficient runway remaining to land ahead, the pilot turned the aircraft left towards the beach for a forced landing.

Impact marks in the sand indicated that, during the landing, the left main wheel struck the ground first followed by the aircraft nose. One propeller blade (wooden) broke off, and the aircraft rotated and rolled onto its right side before coming to rest partially inverted about 22 m from the initial impact mark. The passenger was fatally injured, and the aircraft was destroyed. The pilot was taken to Mackay Hospital and self-discharged on the same day.

The wreckage was removed from the accident site by the Queensland Police Service Mackay Forensic Crash Unit and transported to a secure facility for examination.

Pilot and aircraft history

The ATSB visited Mackay from 12 to 16 January 2022 and the investigation found that:

• The pilot did not hold a Civil Aviation Safety Authority aeroplane pilot licence, aircraft maintenance engineer licence or authorisation to perform or certify for maintenance on the accident aircraft.
• The aircraft was issued with a standard certificate of airworthiness in 1978.
• The pilot purchased the aircraft from the owner-builder in 2011.
• The aircraft logbook statement specified that it was to be maintained in accordance with the Civil Aviation Authority^[2] Schedule 5. All components were lifed ‘on condition’, except those within the scope of relevant airworthiness directive requirements and the engine. The time‑in‑service between maintenance release issue was at 100‑hours or 12‑month intervals, whichever was earlier. The operational category was ‘private’.
• The most recent maintenance release was issued in 2015 by the pilot, who was not authorised to do so. The expiration date was recorded as ‘27/1/16’, the system of maintenance was recorded as in accordance with ‘Schedule 5’ and the operating category as ‘experimental private’. It contained the pilot’s daily inspection certifications for 2015 and further entries in 2021, after the maintenance release had expired (none recorded for the period 2016–2020).
• The aircraft logbook entries for periodic inspections in accordance with Schedule 5 ended with the last entry in March 2011. There was no entry for the maintenance release issued in 2015.
• The engine logbook entries ended in January 2014, with the last entry certified by the pilot.
• The last entry in the pilot’s logbook for VH-WBL was in 2015.

Wreckage examination

The ATSB conducted a preliminary examination of the wreckage, but did not identify anything obvious that would lead to the engine completely failing. Relevant observations are noted below:

• The tachometer indicated a time of about 6 minutes between engine start and the accident.
• The remaining propeller blade did not exhibit any damage, which was consistent with a loss of power.
• The core of the engine was intact with the crankcase free from impact damage and the cylinders securely attached. The engine rotated freely and the valve train was observed to respond to crankshaft rotation.
• A differential pressure (leak) check was performed on the engine cylinders with the engine at ambient temperature. One cylinder recorded a low result for a compression check of 16/80. The others recorded 55/80, 74/80 and 76/80.
• There was sufficient engine oil and the oil filter was relatively clean with no significant debris.
• An internal examination of the exhaust system showed that the muffler inner matrix had collapsed with loss of matrix material to both mufflers. However, the condition of the matrix should not have prevented the operation of the engine.
• The gascolator was dislodged in the accident and no fuel was found in the carburettor float bowl.
• The main fuel tank dip stick was bent during the accident and indicated there was sufficient fuel for flight at impact. This was the tank selected for the flight and was gravity-fed to the engine. The tank had split open, resulting in the loss of all the contents, and therefore no examination of this fuel was possible. The right-wing fuel tank contained blue aviation gasoline (100LL) and the left-wing fuel tank contained green fuel, which was likely a blend of aviation gasoline with yellow unleaded motor gasoline. Both wing tanks passed a water test.
• Although not used on the accident flight, the electric fuel pump for the wing tanks contained fuel that failed a water test. The pump filter was found to be clean and unobstructed.
• A functional check of the engine ignition switch did not reveal any defect with the magneto switching.
• The flight controls were connected and free to move in the correct sense. However, the aileron control cables were significantly corroded at their outboard thimble and sleeve.
• The passenger’s seat belt had completely failed at 2 locations. Both the pilot and passenger’s seat belts were manufactured in May 1973 and were required to be removed from service prior to 1 January 1990 in accordance with Civil Aviation Safety Authority airworthiness directive AD/RES/24: Aeronautique Seat Belts and Harnesses. At the time the airworthiness directive was issued in 1990, the aircraft was being maintained by an approved maintenance organisation.

Safety message

This accident highlights the importance of following standards for the maintenance and operation of aircraft. The Civil Aviation Safety Authority airworthiness directive AD/RES/24 regarding seat belt replacement was cancelled in 2009 with the explanation that ‘As all affected aircraft would have been modified long ago, this AD is no longer required’. However, compliance with this airworthiness directive was missed on this aircraft for about 30 years, despite both seat belts displaying the affected manufacturer’s label and their inspection was a requirement under Schedule 5.

Reasons for the discontinuation

The Civil Aviation Safety Authority have put in place regulations designed to ensure aircraft are airworthy and pilots are properly trained and qualified. When owners operate outside of the rules, they remove the built-in safety defences and undetected problems are more likely to emerge. Given that the aircraft and engine had not been maintained in accordance with the regulations for about 10 years, a more detailed investigation to find the source of the engine failure would have unlikely led to the identification of broader systemic safety issues. On that basis, the ATSB determined that there was limited safety benefit in continuing to direct resources at this investigation when compared with other priorities and elected to discontinue this investigation.

__________

1. Eastern Standard Time (EST): Coordinated Universal Time (UTC) + 10 hours.
2. Predecessor to the Civil Aviation Safety Authority.