What happened
On 18 July 2010, a Reims Cessna FR172H, registration G-RABA, was involved in an accident at Compton Abbas Airfield in Dorset. The aircraft, which was being operated for a banner towing mission, had recently arrived from Blackpool. After landing, the pilot shut down the engine to allow for refuelling.
Following the refuelling process, one pilot entered the cockpit with the intention of taxiing the aircraft to a parking area. During the engine start sequence, the engine immediately surged to high power. This sudden acceleration caused the aircraft to move rapidly forward, striking a hangar. The impact caused severe damage to both wings and resulted in a fuel spillage. The pilot sustained minor injuries and was able to exit the aircraft via the normal door.
The investigation
The AAIB investigation examined the engine start procedure and the circumstances surrounding the aircraft's movement. The investigation established that the pilot had been attempting a "hot start" technique. This method involves setting the throttle to full power and the mixture to lean, then advancing the mixture and closing the throttle once the engine fires.
Investigators noted that the parking brake was not engaged during the refuelling period, and while the pilot believed the brake had been reapplied before the start, this could not be confirmed. CCTV footage showed the pilot moving toward the aircraft door just as the engine ignited and the aircraft accelerated.
Findings
- The engine reached high power immediately upon ignition.
- The short interval between engine shutdown and the subsequent restart likely caused the engine to fire and surge to full power before the pilot could manually close the throttle.
- The parking brake was not confirmed to be engaged during the start sequence.