Accident Bell 206L-1 LongRanger II N79SP,
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ASN Wikibase Occurrence # 34609
 
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Date:Thursday 4 April 1996
Time:12:19 LT
Type:Silhouette image of generic B06 model; specific model in this crash may look slightly different    
Bell 206L-1 LongRanger II
Owner/operator:West Virginia State Police
Registration: N79SP
MSN: 45540
Year of manufacture:1980
Total airframe hrs:2898 hours
Engine model:Allison 250-C30P
Fatalities:Fatalities: 2 / Occupants: 2
Aircraft damage: Destroyed
Category:Accident
Location:Charleston, WV -   United States of America
Phase: En route
Nature:Unknown
Departure airport:, WV (KCRW)
Destination airport:S. Charleston, WV
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
Three minutes after takeoff, an ATC controller heard a garbled transmission with an ELT signal in the background. Witnesses observed the helicopter in level flight, about 300 feet above a hill, when a tail section separated from the helicopter, followed by the helicopter entering a spin, rolling inverted, and descending into trees. The tail boom section aft of boom station 167, which included the upper and lower vertical fin, the tail rotor gear box, and the tail rotor hub and blades, was found 650 feet from the main wreckage. Examination revealed fatigue cracks at the separated area of the tail section. Due to reports of tail boom cracking, an Alert Service Bulletin had been published by the manufacturer in 1987 recommending an inspection of the tail boom every 100 hours, which had been complied with by the operator. The manufacturer and the FAA certification office were aware of a few reports of tail boom cracking, and were not aware of over 220 Service Difficulty Reports that concerned cracks in the Bell 206L tail booms. A doubler was added to the failed area on recent production models; however, no modifications were developed to add a doubler to the failed area of the older models.

Probable Cause: the helicopter manufacturer's inadequate maintenance service bulletin inspection interval which failed to provide timely detection of preexisting fatigue cracks in the tail boom. Factors were: the manufacturer's failure to develop a modification of the failed area, and the failure of the FAA certification office to monitor and act upon the significant number of reports of tail boom cracking that were reported by industry.

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: NYC96GA083
Status: Investigation completed
Duration: 1 year
Download report: Final report

Sources:

NTSB NYC96GA083

Location

Revision history:

Date/timeContributorUpdates
24-Oct-2008 10:30 ASN archive Added
09-Apr-2024 07:37 ASN Update Bot Updated [Time, Other fatalities, Departure airport, Destination airport, Source, Narrative, Category, Accident report]

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