On 11 July 2012, the pilot of a Piper Seneca I, registered VH-LCK, was conducting a freight-carrying flight between Broome and Port Hedland, Western Australia. The flight was conducted at night under the instrument flight rules. Witnesses who heard or saw the aircraft take-off reported hearing unusual noises from the engines during the climb. Other witnesses closer to the accident site reported hearing the engine sound suddenly cut out before the aircraft banked left and descended steeply towards the ground. The aircraft wreckage was located amongst sand dunes, about 880 m beyond the upwind runway threshold. The aircraft was destroyed and the pilot sustained fatal injuries.
What the ATSB found
The take-off towards the ocean was conducted in dark night conditions with limited external visual cues. An on-board global positioning system (GPS) recorded a reducing ground speed as the aircraft approached and passed overhead the upwind runway threshold, but without a significant increase in climb performance. That reduction in ground speed occurred about the same time witnesses heard unusual noises from the aircraft’s engines.
In the absence of any identified environmental, airframe or structural factors, the witness reports and GPS data were consistent with the aircraft’s performance being affected by a reduction in engine power. Following the likely loss of engine power, the aircraft speed reduced significantly, resulting in uncontrolled flight, a steep descent and collision with terrain.
Although not identified as a factor contributing to this occurrence, post-accident examination of the aircraft’s fuel selector valves found the internal seals had deteriorated and allowed fuel to flow to the engines when the valves were in the OFF position. A review of the aircraft manufacturer’s maintenance instructions revealed this type of internal leakage may not be evident during routine maintenance, although a non-scheduled valve leak procedure was available.
What's been done as a result
The aircraft manufacturer has been advised that their maintenance instructions may not identify deteriorated fuel selector internal seals during routine maintenance. Airworthiness bulletin AWB 28-105, published by the Civil Aviation Safety Authority, recommended that owners and operators of Piper Seneca, and other aircraft fitted with similar fuel selector valves, regularly check their function.
This accident highlights the need for pilots to closely monitor their aircraft’s airspeed and initial climb performance during take-off. The need for prompt identification of any performance degradation and optimisation of the aircraft’s available climb performance is emphasised. The accident also highlights the elevated risk associated with dark night conditions, which increase pilot workload, particularly in the case of abnormal aircraft operations.
The investigation also identified the potential for inadvertent operation of the engine magneto switches due to their close proximity to the landing and taxi lights and auxiliary fuel pumps, potentially increasing risk if these switches are operated at a critical stage of flight.