Introduction
On 14 January 2001 at 1345 UTC, a Piper PA-15 (registration G-BTOT) sustained damage during a ground handling incident at Fishburn, County Durham. The aircraft was being operated on a private flight with the sole pilot on board. The pilot held a Private Pilot's Licence with 213 hours total flying experience, including 10 hours on type.
Events
After landing, the aircraft was parked near a fuel bowser and refuelled. It was then pushed away and turned 90 degrees for engine start in preparation for taxiing to the hangar. The control stick was lashed fully aft, and both mainwheels were chocked. The pilot intended to hand-swing the propeller without assistance.
The engine, neither hot nor cold, proved difficult to start. Between attempts, the pilot manipulated engine controls and tried priming and 'blowing out' procedures. For each start attempt, the throttle was set about 3/4 inch open, as was normal practice, with throttle friction set loosely.
When the engine finally fired, it accelerated to an abnormally high speed. The pilot attempted to run around the right wing to reach the throttle, but the left mainwheel rode over its chock. The aircraft swung right until free of the right chock, then accelerated toward a windsock mast, with the pilot still trying to enter the cockpit.
Damage
The left wing struck the mast, causing significant leading-edge damage. The impact pivoted the aircraft around the mast and further increased engine RPM. The pilot stepped clear but the aircraft turned toward him, then missed him and struck one corner of the fuel bowser with the right wing, propeller, and landing gear. The propeller blades penetrated the bowser, but no fire occurred, and the impacts stopped the engine.
The pilot then caught up with the aircraft, switched off fuel and magnetos, and noticed the throttle had moved to a high power setting. Temporary repairs were applied to the bowser holes.
Aftermath
While copying logbook sections for insurers, the pilot discovered a fax message sent to another syndicate member. It stated that the throttle linkage had a tendency to vibrate toward full power unless the throttle friction nut was tight. This information had not been shared with all syndicate members.
In addition to the self-advancing throttle tendency, the pilot attributed the accident to soft ground, which made it easier for the aircraft to overrun the chocks, and to his not expecting the engine to start so vigorously.
Findings
No official probable cause was determined. The pilot identified the throttle linkage issue, soft ground, and unexpected vigorous start as contributing factors.