Incident Overview
The airplane was returned to service on the day prior to the incident flight after undergoing routine maintenance. During the first flight following the maintenance, the right engine's top cowling separated from the aircraft in flight. The pilot responded by securing the right engine, but the airplane could not maintain altitude. A forced landing was initiated, and the pilot identified a suitable area. However, the glide path was insufficient to clear a tree line and buildings, resulting in the aircraft touching down in a clear area approximately 1,500 yards short of the intended landing zone.
Post-Landing Fire
The airplane came to rest in a field of scrub brush. About five minutes after the pilot deplaned, grass beneath the left engine ignited. The resulting brush fire consumed the entire aircraft.
Investigation Findings
Examination of the separated right engine cowling revealed that the outboard latching fasteners were set to the "open" position. The mechanics who performed the maintenance did not follow the procedure outlined in the airplane's maintenance manual to secure the cowling. One mechanic, who had worked on the outboard side of the right engine, could not recall fastening the three primary outboard cowl fasteners before returning the airplane to service.
When questioned, the pilot stated that during the preflight inspection, he "just missed it" regarding the security of the cowling.
Probable Cause
The mechanic's failure to secure the right engine cowling fasteners. Contributing to the incident was the pilot's inadequate preflight inspection.