Primary finding
Probable cause
The loss of engine power during the initial climb due to the disconnection of the turbocharger air intake hose and clamp, and the pilot’s inadequate servicing and preflight inspection of the turbocharger air intake clamp.
Investigator assessment
Analysis narrative
The pilot of the experimental amateur-built helicopter reported that he had hovered around the airport for about 20 minutes without issue and then initiated a takeoff to remain in the traffic pattern. During the initial climb, about 20 to 30 ft above ground level, the engine suddenly lost power and the helicopter yawed to the right. The pilot entered an autorotation and performed a run-on landing on a grass surface. During the landing, the right skid dug into uneven terrain, the helicopter rolled over onto its right side, and a post-crash fire quickly ignited. The pilot was able to extract himself from the helicopter without injury, however, the helicopter was destroyed by the post-impact fire. The pilot reported that after the accident, he discovered an undamaged turbocharger air intake hose clamp directly in his departure path in the grass. Photographs of the turbocharger revealed that the air intake clamp was not installed, and the intake hose had been consumed by fire. The pilot reported that about a week prior to the accident, while the helicopter was being transported on a trailer, he personally adjusted this clamp and intake hose, and he may have forgotten to tighten the clamp. During the initial climb, it is likely that the turbocharger intake hose and clamp separated from its installation area, and as a result, engine power was lost.