Casualties unknown

Engine failure due to fuel injector servo seal separation (N8646P)

Bend, OR, US

On September 28, 1990, a Piper PA-24-260 (registration N8646P) operated by Richard C. Hall was involved in an aviation accident near Bend, OR. Investigators recorded the probable cause as: The separation of a synthetic seal inside the fuel injector servo, which allowed fuel to migrate to the impact tubes. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.

Sourcesthe U.S. National Transportation Safety Board (NTSB) historical archivePrimary reportUpdated 2026-06-10Data APIEditorial standards

A pilot reported severe engine trouble and rough running before crashing into an open field. Investigation revealed a separated synthetic seal in the fuel injector servo allowed fuel migration.

What happened

The pilot communicated with air traffic control to report experiencing severe engine trouble. The engine was described as running roughly, with symptoms suggesting it was starving for fuel. Subsequently, the aircraft wreckage was located in an open field. Investigators noted a tree situated 500 feet from the main wreckage site that exhibited impact damage.

The investigation

A detailed examination of the aircraft components was conducted to determine the mechanical cause of the failure. Inspectors focused on the fuel system components, specifically looking for evidence of fuel starvation or blockage.

Findings

The investigation identified a critical mechanical failure within the fuel system. A synthetic seal located inside the fuel injector servo was found to be separated into two distinct pieces. This separation compromised the integrity of the component, which allowed fuel to migrate to the impact tubes. This mechanical failure is consistent with the pilot's report of engine roughness and fuel starvation prior to the crash.

Safety message

Regular inspection of fuel system seals and injector servos is critical to prevent similar failures. Ensuring the integrity of synthetic seals can help maintain proper fuel flow and prevent engine malfunction during flight.

Probable cause

The separation of a synthetic seal inside the fuel injector servo, which allowed fuel to migrate to the impact tubes.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001212X24366. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.