What happened
On 31 October 2009, a Cessna 172S Skyhawk, registration G-SHSP, was involved in a ground collision at Sleap Airfield, Shropshire. Following a private flight in the local area, the pilot refuelled the aircraft. During the refuelling process, the parking brake was disengaged. After the engine was started, the pilot performed the necessary engine-start checklists.
While the engine was running, the pilot noticed the aircraft beginning to move forward. In an attempt to stop the movement, the pilot applied pressure to the brake pedals. Although the aircraft initially responded to the braking input, it continued to move until it struck an Enstrom 480 helicopter, registration G-LADZ, which was parked approximately 20 metres from the refuelling point. The collision caused damage to the inboard leading edge of both wings of the Cessna 172S Skyhawk and damage to the rear fin and fuselage of the Enstrom 480.
The investigation
Investigators examined the pedal assemblies of the aircraft involved. It was noted that the pilot had previously operated Piper PA-28 aircraft, where the rudder pedal pads and toe brakes are separate components. In contrast, the Cessna 172S Skyhawk utilizes a one-piece rudder pedal installation. While both types of aircraft require pressure applied to the top of the pedals to engage the toe brakes, the physical sensation and mechanical interface differ between the two models.
Findings
- The parking brake was not engaged during the engine start sequence.
- The pilot's initial braking attempt was influenced by muscle memory from operating different aircraft types with different pedal configurations.
- There were no injuries to the pilot of the Cessna 172S Skyhawk.