Casualties unknown

Engine Failure During Test Flight Leads to Spin and Terrain Impact (N725AC)

Richmond Hts., OH, US

On February 7, 1992, an Aero Commander 500S (registration N725AC) operated by Michael Stanton-hicks was involved in an aviation accident near Richmond Hts., OH. Investigators recorded the probable cause as: THE PILOT'S IMPROPER EMERGENCY PROCEDURES AND FAILURE TO MAINTAIN CONTROL OF THE AIRPLANE, WHICH RESULTED IN AN INADVERTENT SPIN AT TOO LOW AN ALTITUDE TO ALLOW RECOVERY. 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

During a test flight after turbocharger waste gate adjustment, the airplane experienced an engine sputter, entered a left spin, and impacted terrain. Examination of the left engine found burnt exhaust valves in two cylinders, with one valve having a preexisting defect, causing power loss.

Incident

A pilot conducted a test flight after having the waste gates on the turbochargers adjusted. The airplane departed and climbed to about 1,000 feet when witnesses heard an engine sputter. The airplane then made a left turn and entered a nose-low, left spin before impacting the terrain.

Engine Examination

A teardown inspection of the left engine revealed that the exhaust valves in cylinders #3 and #5 were burnt through at the valve head. The #5 exhaust valve had a deep preexisting mark on the valve stem. The failures of both valves were sufficient to cause a power failure in the left engine.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001211X14164. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.