What happened
On 13 June 2015, a Team Minimax 91, registration G-MYLB, was conducting a private local flight departing from Fishburn Airfield. After flying northwest and then turning north towards Brandon, the pilot performed routine en-route checks and activated an aftermarket electrical carburettor heater due to humid conditions.
While the aircraft was descending south toward Fishfield at approximately 1,500 ft agl, the engine RPM began to decay before the engine stopped completely. After notifying Fishburn Airfield of the emergency, the pilot identified a field of crops as a potential landing site. Although the pilot attempted to utilize tractor tracks for the approach, the main landing gear struck the standing crops, causing the nose to pitch down and the aircraft to spin to the right. The impact resulted in the aircraft being damaged beyond economic repair, though the pilot escaped with only minor injuries.
The investigation
The AAIB examined the engine failure and the functionality of the carburettor heating system. The pilot initially suspected carburettor icing, which might have been caused by a failure in the electrical heating element. However, testing of the aftermarket heater confirmed that the element was drawing a normal amount of current. It was noted that while the manufacturer of the heater offered an optional cockpit light to indicate current flow, this specific aircraft, G-MYLB, was not equipped with that indicator.
Findings
- The engine power loss was characterized by a decay in RPM followed by a total engine stop.
- The pilot's primary suspicion regarding the cause of the failure was a partial internal engine seizure.
- The electrical carburettor heater was found to be functioning correctly during post-accident testing.