What happened
On 10 July 2003, a Pitts S-1C, registration G-BRJN, was prepared for a private local flight at Sherburn-in-Elmet. After retrieving the aircraft from its hangar and completing a pre-flight inspection, the pilot discovered that the battery was depleted due to the master switch being left in the 'ON' position. To facilitate the engine start, the pilot used jump leads connected to a car battery parked alongside the aircraft.
After starting the engine and adjusting the throttle to a low power setting, the pilot exited the cockpit to disconnect the jump leads. During this process, the aircraft moved forward, jumping the wheel chocks. The Pitts S-1C subsequently collided nose-to-nose with a Zlin aircraft parked inside the hangar. The impact pushed the Zlin into an Extra aircraft, resulting in damage to the propeller tips, engine cowlings, and the leading edge of the top left wing of the G-BRJN. The Zlin aircraft also sustained damage to its propeller, cowling, and an elevator tip, while the Extra aircraft suffered minor cowling damage. There were no injuries to the pilot.
The investigation
The investigation was based on an aircraft accident report submitted by the pilot. The examination focused on the sequence of events during the engine start-up and the effectiveness of the ground equipment used to secure the aircraft. The pilot identified that the use of undersized wheel chocks and a potentially high engine speed contributed to the uncontrolled movement of the aircraft.