What happened
The aircraft experienced an in-flight engine fire while cruising at altitude. Despite the severity of the situation, no emergency calls were transmitted by the crew. The pilot did not shut down the engine, which was the source of the fire. A rear seat passenger attempted to open a rear door to vent smoke but was unable to hold it open and lost consciousness before impact. The aircraft subsequently crashed in an open field.
The investigation
Post-accident examination revealed that the engine manifold was found unbolted, with all bolts missing. Maintenance records indicated the manifold had been removed two weeks prior for repairs. However, no torque value was specified for reinstalling the manifold nuts; the correct specification is 160-180 inch-pounds. Furthermore, the release was not signed off by a mechanic but by the director of maintenance, who was aboard as a passenger.
Findings
The primary contributing factor was fuel exhaustion caused by the engine fire resulting from improper reassembly of the manifold. The absence of specified torque values and the unauthorized sign-off by a non-mechanic passenger contributed to the mechanical failure. The crew's failure to initiate emergency procedures and shut down the engine exacerbated the outcome.
Safety message
Maintenance personnel must strictly adhere to specified torque values during reassembly. Release forms should only be signed by qualified mechanics, not passengers or non-technical staff.