What happened
During a flight originating from Kununurra towards Bellburn, the pilot initially reported that the aircraft was operating as expected. However, the flight was interrupted by a progressive degradation in engine performance. The pilot observed that while most engine indications remained within normal parameters, the fuel flow readings were lower than usual. As the power loss continued, the pilot decided to return to Bellburn Airfield. As the situation worsened, the pilot identified the necessity for a forced landing.
In managing the emergency, the pilot executed a turn into the wind and maintained the optimal glide speed, which helped extend the time available to evaluate landing sites. The pilot also utilized communication with a supporting aircraft, which carried the operator's chief pilot, to assist with troubleshooting during the descent.
The investigation
The investigation focused on the mechanical failure that led to the loss of power. Investigators determined that the performance degradation was consistent with the air intake pipe for the number six engine cylinder becoming loose and eventually detaching during flight. While the detachment of the intake pipe was identified as the primary driver of the power loss, the investigation could not establish why the pipe had become unfastened, noting that a similar incident had occurred in 201s.
Findings
- The detachment of the air intake pipe to the sixth engine cylinder caused the loss of engine performance.
- The specific cause for the intake pipe becoming loose remains undetermined.
- The pilot's recent training in forced landing procedures likely assisted in the effective management of the emergency.
- The use of best glide speed and wind direction considerations helped maximize landing options.
- The pilot's recent practice may have mitigated the risk of mishandling the aircraft and potentially prevented more significant injuries to the pilot and passengers.