What happened
On 4 November 2002, a Commander 114B, registration G-RJCP, was conducting a private flight intended for instrument flying practice near Dartmouth. Approximately 15 minutes into the flight, the pilot observed a reduction in engine power, which was immediately followed by a significant influx of blue smoke into the cockpit.
As visibility within the cabin deteriorated, the pilot attempted to shut down the engine to prepare for a forced landing. During this process, the engine emitted a clicking sound and subsequently seized. The pilot declared an emergency with Exeter Radar and identified a suitable field adjacent to Newcott Farm.
During the approach, the pilot attempted to manage the descent by deploying the landing gear, but found it difficult to maintain the necessary airspeed. The aircraft performed a heavy landing in the field, resulting in the collapse of the landing gear and extensive structural damage to the airframe. The crew members escaped the aircraft without injury.
The investigation
The AAIB investigation focused on the sudden loss of engine power and the presence of smoke. Examination of the Lycoming IO-540-T4B5 engine revealed that the engine had suffered a catastrophic failure. Specifically, the connecting rod for the number four cylinder had detached from its piston and been forced upward, creating a large hole in the crankcase.
Investigators found evidence of overheating on the crankshaft and bearings for the number four, five, and six cylinders, which was consistent with operating under conditions of insufficient lubrication. While the underside of the aircraft showed significant oil staining, a detailed strip examination of the engine failed to identify the specific origin of the oil leak during flight. The oil pump was found to have seized due to extreme heat, though the drive itself remained intact.
Findings
- The engine experienced a catastrophic failure characterized by a detached connecting rod and a breached crankcase.
- The engine showed clear signs of overheating, suggesting a loss of engine oil in flight.
- Although the aircraft's underside and exhaust components showed evidence of oil contamination, the precise source of the leak could not be determined.
- The heavy impact during the forced landing caused the collapse of the landing gear and significant airframe distortion.