Amateur-built LANCAIR LEGACY N368W accident near Reno, Nevada

Probable cause

The shearing of mounting bolts that attached the right turbocharger to its mounting bracket during an air race, which resulted in hot exhaust gases leaking into the engine compartment and starting a fire.

NTSB analysis

The pilot reported that he was participating in an air race when an in-flight fire in the engine compartment and a loss of engine power occurred. He was unable to discharge the fire extinguisher and declared an emergency. He flew off the racecourse and touched down the airplane in rough terrain short of a runway.

Each side of the engine had exhaust pipes from each cylinder that connected to a manifold via a slip joint on each pipe. The manifold connected to a turbocharger at the rear end of the engine, and the turbocharger was mounted to the airframe. Postaccident examination revealed that the two bolts that attached the right turbocharger to its mounting bracket had sheared. The exhaust pipes had pulled down and away from the cylinders, likely due to the weight of the turbocharger and exhaust manifold, which created a gap at the slip joint for the No. 1 cylinder, which was the most aft cylinder and closest to the turbocharger. This allowed hot exhaust gases to escape into the engine compartment and start a fire in the immediate vicinity of the gap. There was also a broken weld at the induction tube that carried turbocharged air from the right turbocharger.

Text from the NTSB. Open the NTSB docket for WPR14LA394 for the full record.