What happened
On 30 July 2007, a Miles M65 Gemini 1A, registration G-AKHP, was involved in a ground collision at Shoreham Airfield, Sussex. The aircraft, which had been recently acquired by its owner for the purpose of a planned familiarisation flight, was taxiing away from the fuel pumps following a refuelling session. While the engines were running and the aircraft was waiting for another aircraft to finish refuelling, the plane began to move forward.
In an effort to halt the movement, the pilot attempted to use the parking brake lever on the instrument panel. During this attempt, the lever fractured at its base and bent backwards, rendering the parking brake ineffective. The pilot subsequently shut down both engines to stop the roll; however, the aircraft continued to move at a slow walking pace. The movement resulted in a collision with the tail of a parked Tiger Moth, causing minor damage to the latter's rudder. There were no injuries to the pilot or the passenger on board the Gemini.
The investigation
Following the incident, the owner conducted an inspection of the braking system. The investigation found no mechanical failures other than the broken parking brake lever, which the owner believed had failed due to the excessive force applied during the emergency stop.
Technical examination of the Miles M65 Gemini 1A braking system revealed that it utilizes cable-operated drum brakes. This system uses a mixing unit to allow for both simultaneous application to both main wheels via the parking brake and differential braking via the rudder pedals. The investigation noted that the rigging of this system is complex, and even a minor error in the rigging process can lead to a significant reduction in braking performance.