What happened
On May 14, 2011, a Beechcraft 35, registration OO-TMM, was performing a flight from Lydd, United Kingdom, to Courtrai, Belgium, carrying the pilot and one passenger. While cruising at approximately 2,000 feet over the English Channel, roughly 8 nautical miles from the French coast, the engine suddenly lost power.
In an attempt to restore power, the pilot adjusted the mixture and switched fuel tanks, but these actions failed to stabilize the engine. Although activating the electric pump caused a momentary increase in engine RPM, the available power remained insufficient to maintain level flight. After declaring an emergency, the occupants prepared for a ditching. Due to the low tide, the pilot opted to land on the beach at Sangatte. The pilot deployed the landing gear and flaps for the approach. During the landing roll, the nose gear collapsed, causing the aircraft to slide several meters before coming to a halt. The aircraft sustained heavy damage.
The investigation
The investigation focused on the mechanical failure of the Continental IO470K engine. Examination of the engine components revealed that the exhaust valve of cylinder number 1 had failed. Specifically, the valve suffered a fatigue fracture that subsequently caused significant damage to the engine.
Investigators also reviewed the maintenance history and environmental factors. The engine's last overhaul had been completed in April 2006, with approximately 500 flight hours logged since that service. The aircraft had flown roughly 63 hours in the nine months preceding the accident. While the pilot regularly washed the aircraft following Channel crossings, the aircraft had been stored outdoors in Scotland, an area with high salt exposure. The engine manufacturer does not mandate specific maintenance or storage protocols for aircraft exposed to salt air.