What happened
On the morning of 22 June 2021, the pilot of a Piper PA-32-300 Cherokee Six, registered VH‑CWK, prepared for a private flight at Moorabbin Airport. The pilot was the only occupant and intended to conduct several circuits to maintain experience in the aircraft type. Between 1129 and 1200 Eastern Standard Time, the pilot performed an engine run up and completed three circuits using runway 35 right without incident or abnormal engine indications.
At 1200, as the aircraft climbed through 505 ft above ground level to complete a fourth circuit, fuel flow to the engine significantly reduced. Within 12 seconds, the engine lost power. Soon after, the aircraft commenced descending. The pilot identified one of few clear areas available for a forced landing and manoeuvred the aircraft towards that area. As the aircraft approached the selected landing area, the pilot recognised that insufficient height remained to clear trees along the southern edge. The aircraft impacted the trees before colliding with rising ground about 35 m beyond the trees. The aircraft was destroyed, and the pilot sustained serious injuries.
ATSB findings
The ATSB found that as the aircraft climbed upwind from the departure runway, fuel flow reduced and the engine lost power. Despite extensive examination, the reason for the fuel flow reduction could not be determined. Recorded data showed a significant reduction in fuel flow leading to the power loss. Notably, after the power loss, fuel flow varied between 20 and 16 l/h, indicating that fuel starvation did not cause the power loss. Wreckage examination, flight records, and witness reports confirmed sufficient fuel on board.
The pilot’s head injuries greatly limited their recollection of actions before and after the power loss. Recorded data showed that RPM reduced at the time and by the amount the pilot intended, suggesting the propeller control was manipulated correctly. At the same time, fuel flow reduced from 113 l/h to 22 l/h. The mixture lever movement required for this reduction was significantly larger than that associated with the intended RPM change and required the lever to be near the cut-off stop. After the accident, the mixture lever was found at a mid-travel position, but impact damage prevented determination of its pre-impact position. Overall, insufficient evidence existed to determine if the mixture control was inadvertently moved.
Examination of the engine and fuel system found no defects that could have caused the fuel flow reduction. The engine was dismantled, and all fuel system components functioned correctly when tested. In summary, a reason for the fuel flow reduction could not be determined.
Incorrect engine variant
The ATSB identified that the incorrect engine variant for the aircraft serial number was inadvertently fitted to VH-CWK. The type certificate data sheet did not specify a serial number range for the K1A5 engine variant but did for the K1G5 variant. This led the maintainer to interpret the data sheet as permitting fitment of the K1A5 instead of the correct K1G5. Past fitment by other maintenance organisations indicated similar interpretations.
However, the aircraft flight manual and illustrated parts catalogue stated the only applicable engine variant for VH-CWK was the K1G5, confirmed by the aircraft manufacturer. The differences between the fitted variant and the correct variant were minor and did not affect the aircraft’s operation or contribute to the power loss and collision with terrain.