What happened
On 31 July 2014, during a public air display at RNAS Culdrose in Cornwall, a Hawker Sea Fury T Mk 20, registration G-RNHF, experienced a sudden loss of thrust accompanied by intense engine vibration. The pilot managed to bring the aircraft down on the runway; however, upon touchdown, the landing gear collapsed. The aircraft veered off the runway and came to a rest on the grass approximately 1,500 feet from the initial touchdown point. The pilot exited the aircraft without assistance and sustained no injuries.
The investigation
Following an initial report, further forensic analysis was conducted by the Royal Navy's 1710 Naval Air Squadron to determine the precise cause of the engine failure. Investigators examined the remains of the Bristol Centaurus eighteen-cylinder radial engine. Despite the extreme destruction within the front section of the engine, forensic work established that severe overheating occurred in the crankpin sleeve bearing of the front bank of cylinders.
This overheating triggered a highly destructive chain of events. The failure caused the bearing to disintegrate, leading to the embrittlement of the master rod through the penetration of liquid tin. As the master rod fractured, fragments of the engine's internal components—including pistons and articulating rods—were propelled through the engine core, damaging the sleeve valve gear and the rear bank of cylinders. The engine continued to rotate until the landing gear collapse caused the propeller to strike the ground.
Findings
- The primary cause of the accident was a localized lubrication problem that led to the severe overheating of the crankpin bearing.
- While the exact initiator of the overheating could not be conclusively identified, several contributing factors were considered:
- The presence of fibrous cellulose debris within the engine, which may have obstructed oil flow to a wrist pin.
- The severe embrittlement of the crankshaft oil retainer gland, which may have caused a loss of internal oil pressure.
- The possibility of hard debris or an unbalanced load causing abrasive wear or excessive stress on the bearing.
- The destruction was intensified by the radial engine's design, where the failure of the crankpin bearing subjected the wrist pins to excessive heat, accelerating the mechanical breakdown.