What happened
On 23 September 2013, a Socata TB10 Tobago, registration G-FAIR, was performing a private flight when the pilot noticed irregular engine performance during the late downwind leg of the approach to Rayne Hall Farm, Essex. The pilot felt the engine was running unevenly and suspected the presence of carburettor ice, prompting the application of carburettor heat and a decision to perform a precautionary high approach.
While the landing itself was completed successfully, the engine ceased running as the aircraft came to a stop on the runway. Shortly after, smoke was observed emerging from the right side of the upper engine cowling. The passenger exited the aircraft and identified a small fire beneath the cowling, which was promptly suppressed using the onboard fire extinguisher. There were no injuries to the two occupants, though the engine and cowlings sustained fire damage.
The investigation
Following the incident, the aircraft's cowlings were removed, revealing significant soot and fire-related damage. Upon activating the electrical fuel pump, investigators observed fuel leaking from the underside of the carburettor.
To further investigate, a maintenance organisation removed the carburettor for laboratory testing. During their examination, the technicians were unable to replicate the leak, and a detailed strip inspection of the component revealed no permanent defects. The maintenance team suggested that the incident may have been caused by a transient instance of the float sticking, which would have resulted in the carburettor overfuelling.