Event Description
While cruising at 8,000 feet, the right alternator light illuminated in the cockpit. The pilot performed the required procedures for an alternator failure. Shortly thereafter, he observed an area of discoloration on the inboard nacelle of the right engine and saw flames inside the nacelle. The pilot secured the engine, declared an emergency, and executed a single-engine landing at Tallahassee, Florida.
Findings
Examination of the engine revealed a broken turbocharger exhaust clamp. This break allowed the exhaust tube to separate from the turbocharger. High-temperature exhaust gases then escaped and ignited a fire. The fire subsequently disabled the alternator wiring, consistent with the earlier alternator warning light.
Metallurgical Examination
Metallurgical analysis of the failed clamp and several others that had also failed indicated that the failures were due to high temperature embrittlement. The lack of high-temperature ductility was attributed to improper heat treatment during the manufacturing process of the clamps.