Amateur-built IVP N4YB accident near Lovelock, Nevada

Probable cause

A total loss of engine power due to the failure of the intake valve in the No. 3 cylinder for reasons that could not be determined based on the available information.

NTSB analysis

The airline transport pilot reported that, while climbing to cruise altitude, about 9 minutes into the cross-country flight, he felt a severe shudder and the engine experienced a total loss of power. Simultaneously, oil began to coat the windscreen. The pilot maneuvered for a nearby airport; however, as he neared the airport, he realized that the airplane would not reach the runway and elected to land in an open area of desert vegetation.

Postaccident examination of the engine revealed a hole in the crankcase above the Nos. 3 and 4 connecting rod journals. The Nos. 3 and 4 pistons were fractured into several pieces, which were located within the engine. The No. 3 connecting rod had separated from the crankshaft. The No. 3 cylinder intake valve head was broken at the bottom of the valve guide; the valve head was not located within the engine.

A visual examination by a metallurgist was unable to determine the initial failure mode given the postfracture mechanical damage to the fractured end of the valve stem and the absence of the separated valve head; however, due to the quantity and severity of damage found throughout the engine, the likely initial point of failure was a fracture to the intake valve in the No. 3 cylinder.

Text from the NTSB. Open the NTSB docket for WPR17LA012 for the full record.