Casualties unknown

1990-03-16: Butler AEROSTAR 601 (N7443S) — Lake Butler, FL

Lake Butler, FL, US

On March 16, 1990, a Butler AEROSTAR 601 (registration N7443S) was involved in an aviation accident near Lake Butler, FL. Investigators recorded the probable cause as: INFLIGHT FAILURE OF THE LEFT ENGINE WHICH WAS CAUSED BY INADEQUATE MAINTENANCE AND INSPECTION BY COMPANY MAINTENANCE PERSONNEL RESULTING IN HEAT DAMAGED MAGNETO LEADS AS A RESULT OF A MISSING EXHAUST FLANGE-TO-TURBOCHARGER SEAL. 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 1781061362Data APIEditorial standards

After leveling at 14,000 ft, the left engine failed. The pilot diverted, then the right engine failed 34 minutes later during fuel crossfeed. Forced landing resulted in collision with a roof and trees. Teardown revealed missing turbocharger seal and finger-tight clamp.

Narrative

Shortly after leveling off at 14,000 feet, the left engine ceased operation. The pilot declared a diversion to Tampa. Approximately 34 minutes later, while still en route, the right engine also failed. During the subsequent forced landing, the aircraft struck the roof of a covered sidewalk and then impacted trees.

Pilot Actions and Fuel Crossfeed

The pilot reported that after losing the left engine, he initiated a crossfeed procedure, transferring fuel from the left tank to the right engine. Approximately 20 minutes of single-engine flight in this configuration elapsed before the right engine quit. The aircraft's flight manual states that in the event of one engine failure, the pilot should land as soon as possible. It further warns that when operating on one engine with fuel crossfeed, absolutely coordinated flight is required to prevent the fuel pickup tube in the tank from becoming unported when the tank is not full.

Maintenance Findings

Teardown examination of the left engine revealed that the seal between the exhaust flange and turbocharger had not been installed. Additionally, the bolt clamp was found to be only finger-tight. The resulting heat had melted the insulation of the wiring harness and the magneto grounding leads. Both 'P' leads were found to be grounded.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001212X22758. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.