NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.
The pilot stated that, during a postmaintenance operational check flight and while on final approach for landing, the fuel pressure indicator light illuminated, and the engine “flamed out.” The pilot lowered the collective to initiate an autorotation; however, due to the low altitude and airspeed, the helicopter subsequently landed hard and rolled over.
During a postaccident examination of the wreckage, a main fuel supply line B-nut fitting was found without the safety wire, and the nut was loose when turned by hand. Before the accident flight, the line had been disconnected during a task to replace the bidirectional suspension cross-bar assembly, and the accident flight was the first flight since the task was performed. According to the noncertificated maintenance technician who performed the task, the line was removed to defuel the fuel tank, which was contrary to manufacturer’s maintenance manual instructions. Based on the evidence, it is likely that the B-nut fitting was not properly tightened and safety-wired during reassembly, which allowed it to back off due to normal engine vibration and resulted in the interruption of the fuel flow during flight.