What happened
During a local skydiving operation, the pilot experienced a complete loss of engine power immediately following takeoff. In an attempt to return to the airport, the pilot initiated a turn; however, it became apparent that the aircraft lacked sufficient altitude and energy to reach the runway. Consequently, the pilot executed a forced landing into an open field.
During the subsequent landing roll, the aircraft type exited the field and crossed a roadway, where it struck a truck. The aircraft then proceeded into a vineyard, where the aircraft nosed over. There were no reported fatalities or injuries in the accident.
Findings
An investigation of the engine identified a fracture in the fuel pressure line connecting the fuel control unit to the airframe fuel pressure transducer. This fracture occurred below the swaged seat of the fitting. Additionally, a supporting clamp intended to secure the fuel line was found to be fractured and separated from the assembly.
Records from the operator indicated that the fuel line had been replaced only the previous night and had been in service for approximately four hours. The previous line had also suffered a fracture. Metallurgical analysis of both the new and old lines showed that they failed due to reverse bending fatigue caused by vibration. The investigation concluded that the failure of the supporting clamp was the primary driver of this sequence, as the broken clamp could no longer prevent the vibration of the tube. It is believed the clamp was either not inspected or was inadequately inspected during the recent maintenance performed on the fuel line.