Background
On 25 January 2008, two pleasure flights were conducted with the Robin DR400/180, registration HB-KED, departing from Sion Airport. Pilots reported no issues. On the morning of 26 January, another pilot (Pilot B) flew the same aircraft for a pleasure flight and landed around 11:00, reporting no malfunctions.
Shortly before noon, the accident pilot (Pilot A) arrived alone at Sion Airport to prepare the aircraft for a private pleasure flight in the Alps with three passengers. He spoke briefly with Pilot B, who informed him that the main fuel tank had been topped up before his 67-minute flight and that the aircraft had no reported defects. Pilot A performed an external check and requested an additional 22 litres of fuel to be added to the main tank, without starting the engine or moving the aircraft.
Accident Sequence
Just before 14:00, Pilot A met his three passengers in the airport terminal and completed travel documents. They walked to the HB-KED. The pilot seated the passengers and took the left seat. He performed customary cockpit checks but did not use the checklist, citing his extensive experience on the type. He attempted to start the engine by pressing the starter button, but the engine did not start. He turned off the magnetos and removed the key from the selector. Leaving the passengers seated, he exited the aircraft, conducted an external visual check, manipulated the propeller slightly, and returned to the cockpit. A second start attempt using the same procedure also failed.
According to the pilot's statements, he again left the cockpit to hand-turn the propeller, still with the three passengers on board. He placed his hands on one of the two metal propeller blades and exerted force in the direction of engine rotation. The pilot was struck on the head by the leading edge of the metal propeller blade, approximately 35 cm from the blade tip. The engine did not start.
Emergency assistance was immediately arranged by one of the passengers and airport personnel. The pilot, seriously injured, was transported to a hospital. The propeller and aircraft were undamaged.
Aircraft Information
The aircraft was a Robin DR400/180, a four-seat, low-wing, single-engine monoplane with fixed tricycle landing gear, constructed of wood and fabric. It was manufactured in 1995 and had accumulated 5085:38 airframe hours. The engine was a Textron Lycoming O-360-A3A, producing 180 hp. The propeller was a two-blade, fixed-pitch metal Sensenich 76EM8S5-0-64. The aircraft had valid certificates of airworthiness and registration.
At the time of the accident, the fuel quantity was approximately 115 litres. The mass and centre of gravity were within limits. The last 1000-hour airframe inspection was performed on 20 December 2007, 32:49 hours before the accident. The last 200-hour engine inspection was also on 20 December 2007.
Examination Findings
After the accident, a witness (also a flight instructor) observed the following cockpit and engine control positions: canopy half open; pilot seat backrest against the instrument panel; flaps in takeoff position; battery and alternator off; throttle pushed forward about 1 cm; mixture rich; carburetor heat cold; fuel selector on main tank; magneto selector on both; parking brake pulled; no wheel chocks.
Inspection of the aircraft revealed that the starter drive was not engaged with the engine flywheel. The starter circuit breaker was found pulled. Some circuit breakers are located on the sidewalls of the front seats; the starter one is on the pilot's side. After resetting the circuit breaker, several engine start attempts were successful with no anomalies. The investigation determined that the aircraft had no defects in the electrical starting system, ignition, or powerplant.
The two-blade metal propeller is attached to the propeller flange with six bolts. The ignition click occurs when the propeller is at the 7-1 o'clock position. The propeller can be installed at the 9-3 or 11-5 positions. The manufacturer's maintenance manual does not specify a required position for propeller installation.
Probable Cause
The accident is due to the fact that the pilot was injured on the head by one of the two metal propeller blades after manually turning the propeller. A contributing factor was the pilot's lack of systematic approach.