Accident Bell TH-1 N106SR,
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ASN Wikibase Occurrence # 367593
 
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Date:Wednesday 20 December 1989
Time:10:20 LT
Type:Bell TH-1
Owner/operator:Scott Paper Company
Registration: N106SR
MSN: 157806
Total airframe hrs:8403 hours
Engine model:LYCOMING T53-L13B
Fatalities:Fatalities: 0 / Occupants: 1
Aircraft damage: Substantial
Category:Accident
Location:Creola, AL -   United States of America
Phase: Taxi
Nature:Unknown
Departure airport:Mt Vernon, AL
Destination airport:Mobile, AL
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
THE ENGINE FAILED WHILE THE PILOT WAS HOVERING AT 110 FT DURING AN EXTERNAL LOAD OPERATION. THE PILOT RELEASED THE LOAD AND AUTOROTATED INTO A SWAMPY AREA. ENGINE TEARDOWN SHOWED EVIDENCE OF SEIZURE AND HEAVY WEAR AT THE #21 BEARING ASSEMBLY ROLLER/SHAFT INTERFACE. METALLURGICAL EXAM REVEALED A BREAKDOWN OF THE TUNGSTEN CARBIDE AND COBALT COATING REPAIR. THE DETONATION GUN (DGUN) REPAIR BUILDUP ON THE BEARING/SEAL JOURNAL, SEO T53-LO-R0035, WAS USED IN 1969, AND CANCELED IN 1970. THE PROCEDURE WAS NOT APPROVED OR PRACTICED BY LYCOMING, AND THE MANUFACTURER RECOMMENDED THAT PARTS REPAIRED IAW THE SEO NOT BE INSTALLED IN ENGINES. THE PILOT WAS OPERATING WITHIN THE 'AVOID OPERATION' AREA OF THE AIRSPEED VELOCITY CHART.

Probable Cause: THE LOSS OF ENGINE POWER DUE TO A #21 BEARING FAILURE. THE BEARING FAILED AS A RESULT OF INADEQUATE MAINTENANCE. A FACTOR IN THE ACCIDENT WAS THE PILOT OPERATING THE HELICOPTER WITHIN THE AVOID OPERATING ENVELOPE.

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: ATL90LA042
Status: Investigation completed
Duration: 2 years and 9 months
Download report: Final report

Sources:

NTSB ATL90LA042

Location

Revision history:

Date/timeContributorUpdates
22-Mar-2024 16:46 ASN Update Bot Added

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