What happened
On 30 July 2000, a Piper PA-25-235, registration G-BPWL, was engaged in a private glider towing operation at Tibbenham Airfield, Norfolk. The pilot was preparing to commence the second tow of the day. Upon receiving the signal to depart, the pilot applied power to the engine. However, the aircraft failed to move forward and instead pitched forward onto its nose.
In an attempt to rectify the situation, the pilot closed the throttle, but the momentum caused the four-blade wooden propeller to strike the runway surface. The impact resulted in the ends of all four propeller blades breaking off. There were no injuries to the pilot during the incident.
The investigation
The investigation focused on why the aircraft failed to accelerate despite the application of power. The pilot, who possessed significant experience in glider towing but had only two hours of experience on this specific aircraft type, provided information regarding the aircraft's behavior.
It was determined that the aircraft's toe brakes were likely still engaged during the takeoff roll. The pilot noted that he typically wore hiking boots for towing operations and believed his feet were clear of the brakes; however, he accepted that the brakes must have been applied. The investigation also considered that because the towing rope was at full tension when power was applied, the pilot may have misinterpreted the resistance felt as tension from the glider rather than braking force.