CEN11LA327 · Piper PA 46-350P

While en route to the destination airport, the pilot noted fluctuation in the engine speed. He diverted to a nearby airport and detected smoke, which increased in intensity. While performing an emergency landing to a highway, the airplane's nose landing gear would not extend. The pilot landed the airplane, which slid to a halt. A postaccident examination revealed thermal distortion to the airplane's nose gear door, which impeded normal operation of the nose landing gear. Clamps on the turbocharger's intermediate exhaust crossover tube were found to be unsecured, which would allow exhaust gases to damage the engine's accessories. The examination also found signatures of thermal distress to the fuel flow transducer and fuel flow transducer line. The unsecured clamps and heat signatures were consistent with exhaust gases compromising the fuel flow transducer line, which resulted in a source of ignition and fuel for the in-flight fire. No additional preimpact mechanical malfunctions or failures were found that would have precluded normal operation. A review of maintenance logbooks noted that a propeller strike had occurred about 3 months before the accident and that repairs were completed about 1 month later, when the engine, including the turbocharger, was removed, cleaned, and inspected. The airplane had flown about 4 hours since the repair.

Verbatim NTSB analysis and probable cause from the NTSB dataset