What happened
On 27 April 2025, a Piper PA-28-181, registration G-JACS, was involved in a serious incident at Fowlmere Aerodrome, Cambridsire. During a private flight operation, the pilot attempted to start the engine after two previous unsuccessful attempts. Following advice from a maintenance engineer, the pilot attempted a further start.
Upon ignition, the engine immediately produced high power. The aircraft began to move, performing a 180-degree right turn followed by a left turn. The pilot was unable to stop the movement using the toe brakes or the parking brake. The aircraft subsequently struck a building. The impact caused the engine to stop and resulted in minor injuries to the pilot's forehead and elbow. The aircraft sustained damage to the engine cowling and both wings, while the propeller was destroyed. The building involved also sustained damage.
The investigation
The AAIB examined the aircraft's braking system and found that both the parking brake and the toe brakes were fully functional. A review of the aircraft's pre-start checklist revealed that the instructions required the throttle to be set to 1/4 inch open. However, investigators determined that the pilot had likely set the throttle to 1/4 of its total operating range. Given that the full throttle movement on this Piper PA-28-181 is approximately 2 inches, the pilot's setting was roughly double the required amount.
Findings
- The engine started at an unexpectedly high power level because the throttle was set excessively open.
- It is probable that the pilot misinterpreted the checklist instruction of 1/4 inch by setting the throttle to 1/4 of its total travel.
- The parking brake was likely not fully engaged, allowing the aircraft to move immediately upon start.
- The pilot's reaction was likely influenced by the startle response, leading to a focus on steering the aircraft rather than reducing the throttle or applying the brakes.