Investigation Summary
Investigation into the 'Amana' crash focused heavily on the fuel system after investigators found evidence of intermittent power loss across all four engines. Post-crash examination revealed that propeller number four was feathered at impact, while the other three were producing power, though witnesses reported hearing the engines cut out and restart multiple times in the final minute of flight. At the time of impact, the aircraft was heading North, rather than East toward its intended track to Cunderdin and Kalgoorlie; investigators speculated the crew was either mid-turn to return to the airport or seeking a clear landing area to the north. A critical discovery was made two months after the accident when magnesium hydroxide corrosion was found in the fuel flow meter of engine number 4, suggesting water contamination. Tests by the Department of Civil Aviation demonstrated that fuel boost pumps could create a vortex holding water in suspension, which would then enter the engines once the pumps were turned off after takeoff. Despite these findings, the court of inquiry could not definitively prove how the water entered the system or if it was the sole cause of the total power loss, leading to an open verdict regarding the primary cause.
Final Conclusions
The official inquiry concluded that the aircraft experienced a total loss of engine power on at least one occasion, leading to a rapid loss of altitude. While evidence suggested fuel contamination by water, the court was unable to determine the exact source of the contamination or confirm it as the definitive cause. Consequently, the official cause of the accident remains undetermined.
Video Analysis
No video analysis linked for this case file yet.
Systems & Failure Modes
Fuel Boost Pumps
Pumps used during takeoff to ensure fuel flow; tests showed they could create a vortex that temporarily trapped water, preventing it from reaching the engines until the pumps were deactivated.
Propeller Feathering System
A system used to stop a propeller from spinning and reduce drag after an engine failure; propeller 4 was found feathered at the crash site.
Vapour Vent Floats
Components in the carburettor fuel strainer chambers that were found crushed by extreme fuel pressure, though this was deemed unlikely to have caused the engine failures.
Interesting Facts
- 01The aircraft was only four years old, manufactured in 1946.
- 02Propeller number 4 was found in the feathered position, indicating the crew had intentionally shut it down.
- 03Investigators found magnesium hydroxide in the fuel passages, a byproduct of magnesium reacting with water.
- 04The aircraft struck trees at an estimated speed of 250 miles per hour (400 km/h).
- 05Ground staff in Perth were pressed for time during the final refuelling due to an engineer's illness and did not check the fuel tanks for water.
Safety Actions & Advisories
Fuel Testing Procedures
The investigation highlighted the inadequacy of checking for water only before the first flight of the day, leading to recommendations for more frequent fuel tank drainage checks.