What happened
Following routine maintenance completed the day before the flight, an aircraft experienced a mechanical failure during its initial mission. While in flight, the upper cowling of the right engine became detached from the airframe. In response to the loss of the component, the pilot managed to secure the right engine; however, the aircraft's performance was significantly degraded, leaving it unable to sustain its previous altitude.
Unable to maintain flight levels, the pilot searched for a suitable location for an emergency descent. Due to an insufficient glidepath to bypass nearby buildings and a line of trees, the pilot executed a forced landing in a cleared area located approximately 1,500 yards from the original intended destination. The aircraft settled in a field of scrub brush. Shortly after the pilot exited the aircraft, a fire ignited beneath the left engine area, eventually consuming the entire airframe.
Findings
Investigations into the incident revealed that the maintenance performed on the previous day was not completed according to the required procedures. Specifically, the mechanics failed to properly secure the right engine cowling using the methods prescribed in the aircraft's maintenance manual. An examination of the hardware showed that the outboard latching fasteners were left in the open position. While the pilot performed a preflight inspection, the unsecured fasteners were not identified prior to takeoff.