North American NAVION N8884H accident near El Cajon, California

Probable cause

A total loss of engine power for reasons that could not be determined because postaccident examination of the airframe and engine did not reveal any anomalies that would have precluded normal operation.

NTSB analysis

The private pilot was conducting a cross-country flight. He reported that the takeoff was normal and that, shortly after takeoff, the engine experienced a sudden loss of all power. The pilot banked the airplane to return to the airport but determined that the airplane would be unable to reach the airport. Subsequently, the pilot initiated an off-airport landing to a parking lot, where the airplane landed hard and slid into an embankment near a fence. A postimpact fire ensued.

A postaccident examination of the airframe and engine found that the fuel manifold valve had thermal discoloration of its housing. The valve was disassembled, and the plunger internal parts (the collar, valve, and spring) were found separated in the plunger cavity. The plunger internal parts likely did not separate during flight; such a condition would have resulted in a rich-running engine, which would not have caused a significant loss of engine power and would have been revealed as a sooty residue on the spark plug electrode areas. The examination of the spark plugs revealed light amounts of deposits, consistent with normal fuel-air mixture and operation. Thus, the separation of the plunger internal parts was consistent with thermal exposure during the postimpact fire.

The melted plastic material found in the fuel selector valve cavity during the disassembly was likely the material that made up the internal control shaft. The throttle control rod end remained secured to the throttle control arm, but the rod end could slide about ½ inch along the bolt that attached the rod end to the control arm. It is unlikely that this movement caused the loss of power during flight given that the pilot did not report an engine control problem.

The examination of the airframe and engine did not reveal any preimpact anomalies that would have precluded continued flight and caused the loss of engine power.

Text from the NTSB. Open the NTSB docket for WPR18LA049 for the full record.