What happened
On 30 July 2015, a Pitts Super Stinker 11-260 (registration G-IIIV) was conducting a private flight for the purpose of aerobatic practice. During the execution of a routine maneuver, the pilot noted that the engine began to run roughly and experienced a significant drop in available power.
In an attempt to rectify the issue, the pilot adjusted the mixture to rich and activated the electric fuel pump; however, these actions failed to restore engine performance. Faced with declining power, the pilot performed a forced landing in a nearby field adjacent to Leicester Airport. The landing site featured a 30° upslope and was occupied by sheep. While the aircraft sustained substantial damage to the engine, propeller, landing gear, rudder, and top wing, the pilot escaped the wreckage without injury.
The investigation
Investigators examined the aircraft and the circumstances surrounding the power loss. An initial inspection of the engine by the aircraft's constructor and maintainer did not identify any immediate mechanical defects.
It was noted that because of the specific configuration and the length of the pipework on this modified model, it is possible that air entered the fuel supply system during the aerobatic maneuvers. The investigation considered that such air ingestion might have persisted in the system for some time before clearing.
Findings
- The engine experienced a loss of power and rough running during aerobatic flight.
- Air ingestion into the fuel supply system during maneuvering is a suspected factor due to the extended length of the fuel pipework on this specific aircraft model.
- The pilot successfully executed a forced landing despite the terrain conditions.