Accident Overview
During cruise flight at 6,000 feet, the pilot reported to air traffic control that he had an engine fire and needed to land immediately. Subsequently, the airplane's left wing separated in-flight, and the airplane crashed in an uncontrolled descent.
Investigation Findings
An investigation revealed that the number six cylinder on the left engine had separated in-flight. Metallurgical examination of the cylinder revealed a fatigue fracture. The fatigue originated at a corrosion pit between the cylinder's cooling fins.
Fire and Wing Separation
There was evidence that fire erupted and spread to the left wing fuel tank, leading to separation of the wing. Additionally, heat streaking was noted on the left engine cowling and left horizontal stabilizer.
Engine Service History
Aircraft records showed that the engine had accumulated 1,682 hours of flight time since it was last overhauled on May 19, 1975.