Incident Overview
Eleven minutes after departure, the pilot reported smoke and a problem with the right engine. Shortly thereafter, the pilot transmitted that the aircraft was 'going down'. During the event, the right wing and engine assemblies separated in flight.
Fire and Damage
Fire damage was concentrated in the vicinity of the right engine's left turbocharger. The tailpipe assembly had separated. Heavy smoke and heat damage were observed between the right wing's forward and aft spars.
Exhaust System Failure
Examination of the exhaust system revealed that the tailpipe had failed in fatigue near the flange where it attached to the turbocharger exhaust port. Evidence indicated that the gasket between the flanges was not uniformly seated. Additionally, the right engine's lower left engine mount was deteriorated, with a significant portion of rubber missing.
Maintenance History
A service bulletin (Piper SB #818, AD87-07-09) had been accomplished on May 21, 1988. This bulletin required removal and inspection of the exhaust system for cracks, and reinstallation with new flange gaskets.
Investigation Findings
The official probable cause states: Inflight engine/wing fire due to a failure of the right engine's left exhaust tailpipe. The exhaust tailpipe failed in fatigue as a result of fluctuating stresses induced by a deteriorated engine mount in conjunction with unevenly distributed clamping loads caused by an improperly seated gasket.