History of the Flight
On 18 February 2006, at approximately 1800 hours UTC, a Schweizer 269C-1 helicopter, registration G-CCJE, was engaged in a private flight at Sheffield City Airport. The purpose of the flight was to demonstrate the helicopter to a passenger who had five hours of experience as a PPL student on Robinson R22 helicopters and had recently purchased a similar Schweizer 269 CBi model. The takeoff and upper air work were uneventful. On return, the passenger requested an autorotation demonstration. The commander decided to perform a practice engine-off landing with power recovery due to light and variable winds. The appropriate checks were conducted on approach at around 1,000 ft agl, and a reference point was chosen on Runway 28.
The entry into autorotation was normal, with an initial speed of 60 kt, later reduced to 50-55 kt to reduce ground speed. At 500 ft agl, engine temperatures and pressures were checked and descent rate appeared normal. The flare was commenced at about 150 ft with an accompanying throttle opening, but no increase in engine noise was apparent. The flare was progressively tightened but had little effect. It became clear that the aircraft would strike the ground with a high rate of descent. The commander attempted to cushion the impact by raising the collective lever. The helicopter struck the ground, which had been softened by earlier rain. The front of the skids dug in, causing the helicopter to tip forward and to the right, coming to rest on its right side. The engine was not running at impact. The commander pulled the fuel shut-off lever and turned off the battery. Both occupants left via the shattered canopy, suffering only minor cuts and bruises. There was no fire. After leaving the aircraft, the commander observed that the wind sock indicated the approach had been flown with a tailwind component.
Examination of the Helicopter
Examination of the helicopter, including the engine, failed to find any pre-accident defects. The helicopter had been flying close to its maximum permitted weight. Photographs of the accident site showed the main rotor blades lying in a coned position, indicating low rotor speed at the time of ground impact.
Engine Testing
The engine, a Lycoming HIO-360-G1A piston engine, was removed from the airframe and installed in a test cell. It was run in the 'as found' condition. Apart from some smoke from accumulated oil, it ran normally throughout the test schedule, including checks of each magneto and 'slam' accelerations and decelerations. The engine picked up cleanly during each acceleration. Oil pressure was slightly low but considered not significant. The engine-driven fuel pump delivered satisfactory fuel pressure.
Analysis
The pilot reported that the combined weight of himself and passenger, along with an estimated 68 kg of fuel, brought the all-up-weight to within approximately 20 kg of the maximum. Higher all-up-weights result in higher descent rates during autorotation and additional height loss during the flare. Some instructors on this type maintain an airspeed of 60 kt or more to preserve rotor speed. The available evidence does not entirely discount an engine problem during the descent, but the test cell results did not suggest any such problem. The helicopter's fuel system is designed such that even with a failed boost pump, gravity feed and engine-driven pump would maintain supply. Induction icing was considered remote due to fuel injection.