What happened
On 18 April 2015, a private flight operation involving a Minicab (JB01 Standard), registration G-ATPV, resulted in an accident at Fenland Airlag, Lincolnshire. The aircraft, which lacks a starter motor, was being started by the pilot using the manual hand-swinging method.
As the pilot attempted to start the engine, the aircraft experienced an unexpected high-power start. The engine ignited with the throttle in the fully open position, causing the aircraft to pitch forward abruptly. In an attempt to move toward the cockpit to shut down the engine, the pilot was struck repeatedly on the forearm by the rotating propeller. The forward momentum of the aircraft caused the propeller to strike the ground, destroying it and subsequently stopping the engine. The pilot sustained one serious injury.
The investigation
The investigation established that the pilot's intended procedure involved pumping the throttle to use the carburettor's acceleration jet, leaving it fully open, and then retarding it to a specific start position before swinging the propeller. However, evidence from the aircraft's position and the throttle lever indicated the throttle remained fully open during the start.
The pilot, an experienced flyer with 394 total hours, noted that he had likely omitted the step of retarding the throttle. He also noted a personal decision to not tie back the control stick to prevent the aircraft from becoming airborne during a high-RPM start, a choice that contributed to the aircraft tipping forward.
Findings
- The primary cause of the accident was an unintentional lapse in the starting procedure, where the pilot failed to retard the throttle from the fully open position.
- The pilot's decision not to use a checklist or secure the control stick contributed to the sequence of events.
- The pilot experienced a cognitive error where he perceived the throttle to be in the correct position because he saw what he expected to see rather than the actual setting.
- The unconventional control layout of the aircraft hindered airfield personnel attempting to assist in shutting down the engine during the emergency.