Introduction
On Saturday, 14 May 2011, at 16:15 local time, a Beechcraft 35 aircraft registered as OO-TMM, powered by a Continental IO-470K engine, was involved in an accident near Sangatte, France. The aircraft was privately operated.
Flight Details
The pilot, accompanied by a passenger, departed from Lydd Aerodrome in the United Kingdom with the intention of returning to Courtrai, Belgium. The flight was proceeding normally until the aircraft reached an altitude of approximately 2,000 feet over the English Channel, about 8 nautical miles from the French coast.
Engine Failure and Forced Landing
At that point, the pilot reported that the engine abruptly stopped delivering power. The pilot adjusted the mixture and switched fuel tanks, but these actions had no effect. Activating the electric fuel pump resulted in a brief momentary increase in engine RPM, but insufficient power remained to maintain level flight. The pilot declared an emergency with air traffic control, and the occupants prepared for a ditching. Noting that the tide was low, the pilot chose to land on the beach. He extended the landing gear and flaps and touched down. During the landing roll, the nose gear collapsed, causing the aircraft to slide several meters before coming to rest. The aircraft sustained substantial damage.
Investigation Findings
Examination of the engine revealed that the exhaust valve on cylinder number 1 had failed due to fatigue, leading to engine damage. The initiation of the fatigue crack was likely facilitated by the presence of oxidation. The last major overhaul of the engine had been performed on 14 April 2006, and the engine had accumulated approximately 500 hours since that overhaul. The aircraft had flown about 63 hours in the nine months preceding the accident. The pilot regularly used the aircraft for cross-Channel flights, having made 11 such crossings in the nine months prior to the accident. The engine manufacturer did not prescribe specific maintenance actions for aircraft exposed to salt air. The aircraft owner regularly washed the aircraft after Channel crossings. The aircraft was stored in a hangar at its home base and was parked outdoors when at a coastal location in Scotland.
Conclusion
The accident was due to the failure of the exhaust valve of cylinder number 1, probably favored by the presence of oxidation.