Air Accidents Investigation Branch
Summary:
During an IFR flight from Le Touquet to Wellesbourne, the pilot observed oil leaking from the left engine followed by engine vibration. He shut the engine down and descended but elected to continue the flight toward Wellesbourne. On reaching 2,000 ft he found he was unable to maintain level flight on one engine and decided to land in a field.
The investigation found the left engine failed due to a fatigue crack in one of the cylinder barrels. It is likely that the pilot was unable to maintain level flight on the right engine due to a combination of engine wear resulting in reduced power available and the prevailing weather conditions. His decision to continue the flight following the engine shutdown was likely to have been influenced by high workload and plan continuation bias.
The maintenance organisation has taken safety action to enhance its maintenance programme for aircraft fitted with piston engines operating beyond the manufacturers recommended overhaul life.