Casualties unknown

Left Stabilizer Spar Fracture Causes In-Flight Vibration and Control Oscillation (N4641D)

Arlington, WA, US

On September 15, 1993, a Beech G35 (registration N4641D) operated by Philips, J. B. was involved in an aviation accident near Arlington, WA. Investigators recorded the probable cause as: FRACTURE OF THE LEFT STABILIZER SPAR. 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 landing pattern entry, a pilot felt a bump followed by vibration and control column oscillation. After throttle reduction and RPM increase, vibration stopped. Post-flight inspection found left stabilizer spar completely fractured at outboard bolts; metallurgical exam showed overstress separation with no preexisting crack.

Incident Description

While entering the landing pattern, the pilot perceived a bump. This was immediately followed by a vibration and a fore-and-aft oscillation of the control column. In response, the pilot increased engine RPM and reduced throttle and speed. The vibration subsequently ceased. The aircraft then landed without further incident.

Examination Findings

A post-flight inspection of the aircraft revealed that the left stabilizer spar had sustained a complete fracture through the upper and lower outboard bolts. The ruddevators were weighed and found to be within balance tolerance limits.

Metallurgical Examination

Metallurgical analysis of the fractured spar indicated that there were no preexisting cracks. The fracture characteristics were described as typical of an overstress separation.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001211X13497. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.