What happened
While flying from Gunnedlar to Archerfield, the pilot of VH-UQI, a Lycoming powered aircraft, experienced a catastrophic engine failure approximately 22 km southwest of the destination. During the emergency, smoke and oil from the engine coated the windscreen, significantly reducing visibility. The pilot attempted an emergency landing in a 400-meter paddock, but because the approach was conducted with a 9 kt tailwind, the aircraft's groundspeed was higher than anticipated. The aircraft touched down late in the available clearing, bounced over undulating terrain, and ultimately struck trees at the boundary of the field. The impact resulted in one serious injury and the total destruction of the aircraft.
The investigation
The investigation focused on the mechanical failure of the engine and the circumstances of the landing. Investigators examined the engine's history and found that the number 2 connecting rod journal bearing had likely failed. While the exact cause of the bearing failure could not be conclusively determined, the engine was fitted with older, pre-modification aluminium-tin alloy bearings, which were known to be susceptible to material separation.
Records indicated the engine had not been overhauled since 1997, meaning it had exceeded the manufacturer's recommended 12-year overhaul interval. Had the overhaul occurred, the engine would have been upgraded to more durable copper-lead alloy bearings. Additionally, the aircraft had seen very low usage, averaging only 14 hours per year, and there was no evidence that specific engine preservation measures had been taken during periods of inactivity.
Findings
- The primary cause of the engine failure was a mechanical breakdown of the number 2 connecting rod journal bearing, likely due to material degradation.
- The pilot performed a downwind landing, which increased the required stopping distance and led to the aircraft overrunning the safe area.
- Reduced visibility caused by engine smoke and oil hindered the pilot's ability to manage the emergency landing.
- Limited aircraft familiarization regarding slow-speed performance contributed to the difficulty of the landing.
- Risk factors were increased by the absence of an emergency locator transmitter and the pilot's failure to leave a flight plan with a responsible person, which could have delayed search and rescue efforts.