What happened
On January 26, 2008, at Sion Airport, a pilot prepared a Robin DR400/180, registration HB-KED, for a private VFR flight through the Alps with three passengers. After completing external inspections and refueling, the pilot boarded the aircraft and performed cockpit checks. Relying on his extensive experience with this aircraft type, the pilot opted not to use the official checklist.
When the pilot attempted to start the engine using the starter button, the engine failed to ignite. After a second unsuccessful attempt, the pilot exited the cockpit to manually rotate the propeller. While applying force to one of the metal blades, the pilot was struck in the head by the propeller's leading edge. The incident occurred while the three passengers remained seated inside the aircraft. The pilot sustained serious injuries and required emergency medical transport to a hospital.
The investigation
Investigators examined the aircraft and found no mechanical defects in the engine, ignition, or electrical systems. However, they discovered that the starter circuit breaker had been pulled to the 'OFF' position, which prevented the engine from cranking. It was suggested that the pilot might have accidentally bumped the breaker while exiting the cockpit.
Technical analysis revealed that the propeller was installed in a position (7 o'clock to 1 o'clock) that makes manual priming particularly difficult, as it requires the pilot to lean forward significantly. Furthermore, the investigation noted that the aircraft's checklist did not specifically require a check of the circuit breaker positions, and the club's internal checklist did not specify the required state for these components.
Findings
- The primary cause of the accident was the pilot being struck by the metal propeller blade during manual rotation.
- A contributing factor was the lack of systematic procedure by the pilot, specifically the decision to bypass the checklist.
- The use of the checklist might have identified the disengaged starter circuit breaker.
- The pilot's decision to perform manual priming while leaving passengers inside the cabin presented an unnecessary risk.