Navion NAVION G N249KC accident near Adrian, Michigan

Probable cause

A leak in the gascolator, which allowed air to enter the fuel system and resulted in a partial loss of engine power.

NTSB analysis

The flight instructor and private pilot had completed training maneuvers and were returning to the airport when the engine experienced a partial loss of power about 1,000 to 1,500 ft above ground level. They were unable to glide the airplane to an open field and descended into a wooded area. The airplane impacted trees and became wedged between trees, suspended above the ground. The engine and empennage separated from the rest of the airplane and came to rest on the ground nearby. The fuel tanks were damaged and most of the remaining fuel spilled onto the ground.

A postaccident examination of the engine revealed no pre-impact anomalies that would have precluded normal operation or production of rated horsepower; however, an examination of the gascolator showed that it had been leaking fuel from three locations and contained a significant amount of debris. In a postaccident examination, the gascolator was subjected to the relevant service bulletin testing and did not pass the test due to the leaking seals and drain valve. Since the gascolator was unable to seal properly, it would have allowed air into the fuel system, which would have resulted in a loss of engine power. A review of the airplane maintenance records revealed no record of compliance with the service bulletin, nor was compliance mandatory.

Text from the NTSB. Open the NTSB docket for CEN17LA316 for the full record.