On May 7, 1991, a Bell 206B-3 (registration N717NH) was involved in an aviation accident near Houston, TX. Investigators recorded the probable cause as: Failure of the main drive shaft coupling due to misalignment resulting from an oil-soaked and delaminated engine mount, and a lack of lubrication in the coupling. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During an aerial video flight over Houston, a helicopter's main drive shaft coupling failed, forcing an autorotation. The pilot attempted to land in a parking lot but crash-landed on an apartment roof. Investigation revealed an oil-soaked, delaminated engine mount causing misalignment and a lack of lubrication in the coupling.
Incident Overview
A helicopter conducting an aerial video flight over metropolitan Houston experienced a failure of the main drive shaft coupling. The pilot was forced to perform an autorotation and attempted to land in a parking lot but was unable to reach it. The helicopter subsequently crash-landed on the roof of an apartment building.
Investigation Findings
An investigation disclosed that the engine mount was oil-soaked and had delaminated, causing misalignment of the drive shaft. Additionally, a lack of lubrication was noted in the main drive shaft coupling. Other maintenance discrepancies were also observed during the investigation.
Probable cause
Failure of the main drive shaft coupling due to misalignment resulting from an oil-soaked and delaminated engine mount, and a lack of lubrication in the coupling.
Frequently asked questions
What happened in the 7 May 1991 Bell 206B-3 accident near Houston, TX?
During an aerial video flight over Houston, a helicopter's main drive shaft coupling failed, forcing an autorotation. The pilot attempted to land in a parking lot but crash-landed on an apartment roof. Investigation revealed an oil-soaked, delaminated engine mount causing misalignment and a lack of lubrication in the…
What aircraft was involved and where did it happen?
The accident on 7 May 1991 involved a Bell 206B-3, registration N717NH, at Houston, TX.
What was the probable cause of the accident?
Failure of the main drive shaft coupling due to misalignment resulting from an oil-soaked and delaminated engine mount, and a lack of lubrication in the coupling.
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