What happened
On December 21, 1989, a Piper aircraft, registration N6894Y, was operating at an altitude of approximately 6,000 feet when the pilot encountered difficulties with the right engine. The flight crew initially reported an engine fire on the right side of the aircraft. Shortly after this report, the pilot communicated that efforts to shut down the malfunctioning engine had been unsuccessful.
At 10:34:37, the pilot transmitted a final message stating that the right engine had detached from the airframe and that the aircraft had entered a downward spin. The pilot was the only person on board the aircraft at the time of the accident and sustained one fatality.
Findings
Post-accident investigations determined that the exhaust tailpipe of the left turbocharger on the right engine had separated from its mounting. A metallurgical analysis of the component identified that the failure was caused by fatigue cracking within the tailpipe.
Maintenance records indicated that while a previous inspection related to Piper service bulletin 920 had been completed, the secondary requirement for adding a fire detection system remained unaddressed because the necessary kits were unavailable. The separation of the exhaust stack allowed intense heat to compromise the structural integrity of the right wing's main spar, leading to the engine's detachment.