NAVION NAVION G near Adrian, MI — 2017-08-11

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 narrative

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.

Analysis

Primary failure mode

Fuel management

First missed decision gate

Failure to inspect and maintain the fuel system as per service bulletin requirements.

NTSB coding

• Loss of engine power (partial) · Maneuvering
• Maintenance

Evidence available

• Photos
• 10 docket documents

Docket documents10

• Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1form
• Release of Aircraft Wreckage, NTSB Form 6120.15form
• FAA Inspector's Statementinterview
• Statement of Party Representatives to NTSB Investigationinterview
• FAA Airworthiness Concern Sheetother
• Maintenance Recordsother
• Navion Service Bulletin No. 106Aother
• Photosphotos
• Reports from Local Agencies - Sheriffreport
• Reports from Parties to the Investigation - Continental Motorsreport

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