History of the Flight
On 13 August 2005 at 1517 UTC, a private Mooney M20J, registration N201YK, departed from Archerfield for a local flight with the sole pilot on board. The pilot, who also owned the aircraft, reported that the engine began to run roughly while en route. He turned the aircraft back toward the departure airfield but before reaching it, the engine emitted smoke and then failed completely overhead a large field. The pilot noted that this field coincided with a proposed future airstrip, making it suitable for a forced landing. He deployed the flaps and landing gear and executed a successful landing in the field, touching down more than halfway into it and stopping in approximately 170 meters, close to the end. He had selected the magnetos and battery master switch to off shortly before touchdown. The pilot, aged 56, held an Airline Transport Pilot's Licence with 12,000 hours total flying experience, including 25 hours on type. His recent flying experience included 85 hours in the last 90 days and 24 hours in the last 28 days. No injuries were reported, and the airframe was undamaged, though the engine sustained damage.
Engine Failure Assessment
The pilot's initial assessment suggested the engine failure resulted from a loss of oil through a hole in the crankcase. The oil level had been satisfactory during the pre-flight inspection. Other information received indicated an internal failure had caused the crankshaft to fail and a connecting rod to penetrate the crankcase. The AAIB determined that an examination of the engine was necessary and contacted the pilot to arrange for the engine and its log books to be sent to the AAIB facility at Farnborough. However, due to a misunderstanding, the engine was shipped to a supplier in the USA. The AAIB has been unable to trace or contact the named US supplier, and as of the report, the cause of the engine failure has not been determined. The aircraft had been laid up for approximately three years before receiving an annual inspection and flying a small number of hours between that inspection and the accident. The engine log books contained no record of preventive maintenance, such as inhibiting or periodic ground running, during the laid-up period, which could provide possible reasons for the failure.
Additional Information
The pilot submitted an Aircraft Accident Report Form, and the AAIB conducted inquiries. The AAIB expressed that if a report from the US supplier becomes available, it is unlikely to contain the necessary depth of information to determine whether further safety issues exist concerning this engine type.