What happened
On 22 August 1998, a Piper PA-28, registration G-BXVC, was conducting a private training flight when the engine experienced a sudden power surge followed by a rapid drop in oil pressure. As the engine ceased operation, the pilot attempted to declare an emergency to Lydd. During this period, smoke was observed emerging from the engine cowling, though the smoke dissipated as the aircraft began a rapid descent.
The pilot managed to execute a forced landing using full flaps, touching down at 65 kt. During the subsequent ground roll, the aircraft reached a speed of 20 kt when the pilot attempted to steer away from a nearby ditch. The aircraft failed to respond to the control input and crossed the ditch, causing the nose and right landing gear to collapse and the propeller to strike the ground. There were no injuries to the two crew members on board.
The investigation
Investigators examined the aircraft and conducted a strip examination of the engine. They noted oil residue on the underside of the fuselage and found oil accumulating in the bottom of the rudder. The engine crankcase contained holes, though the external surfaces of the engine showed no signs of oil contamination.
Upon inspection of the engine, approximately 4 pints of oil were drained. The internal examination revealed that the big end bearings had overheated due to insufficient lubrication, particularly at the rear of the engine. Evidence showed that one connecting rod had detached from its big end and become bent around the camshaft, a condition indicating that extreme temperatures had been reached during the failure.
Findings
- The engine failure was caused by overheating of the big end bearings resulting from a lack of oil.
- The loss of oil was consistent with the oil filler cap being missing during the latter portion of the flight.
- Internal engine pressure, potentially caused by a gas leak past a piston or air entering through the filler tube, may have forced oil out through the crankcase breather.