The ATSB investigation into the fatal accident at Canley Vale, New South Wales (NSW) on 15 June 2010 has yielded important safety messages for pilots when flying twin-engined aircraft with one engine shut down:
- The optimal speed must be flown and the maximum continuous power selected on the operative engine to achieve the aircraft’s published one engine inoperative performance.
- It is important to verify the aircraft’s performance before conducting a descent.
- Pilots should use the appropriate PAN or MAYDAY phraseology when advising Air Traffic Control (ATC) of non-normal or emergency situations.
The accident occurred during a flight from Bankstown Airport, NSW to Archerfield Airport in Queensland. The Piper PA-31P-350 Mojave, with a pilot and a flight nurse on board, was being positioned to Archerfield for a medical patient transfer flight from Archerfield to Albury, NSW. Twelve minutes after taking off, the pilot reported to ATC that he was turning the aircraft around as he was having ‘a few problems.’ He shut one engine down due to an unspecified ‘engine issue.’
The Civil Aviation Safety Authority has since started a project to amend advisory material relating to multi-engine aircraft training and operations to include guidance information about engine problems encountered during the climb and cruise phases of flight.
Over the next 13 minutes, as the situation worsened, the pilot and ATC maintained communications, attempting to work out the best options. The pilot advised that he would have to land the aircraft on a road. Although clearly in an emergency situation, the pilot did not use the PAN or MAYDAY terminology in his communications.
At about 0806 Eastern Standard Time, the aircraft collided with a powerline support pole at Canley Vale. Both occupants were fatally injured and the aircraft was destroyed by the impact forces and an intense post-impact fire.
The Australian Transport Safety Bureau (ATSB) commenced an in-depth investigation immediately. The investigators constructed a detailed chronology, using information from recordings of radio communication between the pilot and ATC, recordings of radar data, ATC documentation, meteorological data and post-accident witness interviews. The aircraft’s position and altitude were obtained from radar data recordings and plotted on an extract of the Sydney Visual Terminal Chart.
The fact that the pilot had not given much detail about the nature of the problems he was experiencing created a challenge for the investigation. Examination of the engines, propellers and governors and other aircraft components found no evidence of any pre-impact faults. In order to understand the engine performance during the occurrence, the ATSB conducted a spectral analysis of the pilot’s radio transmissions. The changes in frequencies of signals from the aircraft’s propellers and alternators throughout the transmissions gave valuable indications about the operation of the engines. The investigator's discovered that, when the pilot reported to ATC that he was turning the aircraft around, there had been surging of an engine which was consistent with uneven fuel distribution to the cylinders.
It was found that, following the shutdown of the right engine, the aircraft’s airspeed and rate of descent were not optimised for flight with one inoperative engine. In addition, the spectral analysis indicated it was unlikely that the left engine was being operated at maximum continuous power as the aircraft descended. As a result, the aircraft descended to a low altitude over a suburban area and the pilot was then unable to maintain level flight, which led to the collision with terrain.
The Civil Aviation Safety Authority has since started a project to amend advisory material relating to multi-engine aircraft training and operations to include guidance information about engine problems encountered during the climb and cruise phases of flight. This amended guidance material will include information about aircraft handling, engine management, and decision-making during these phases of flight.
Read the report: Collision with terrain - Piper PA-31P-350, VH-PGW, 6 km north-west of Bankstown Airport, New South Wales, on 15 June 2010