Accident Bell 206B N83139,
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ASN Wikibase Occurrence # 363047
 
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Date:Tuesday 25 August 1992
Time:10:43 LT
Type:Silhouette image of generic B06 model; specific model in this crash may look slightly different    
Bell 206B
Owner/operator:Alaska Public Safety
Registration: N83139
MSN: 1018
Year of manufacture:1973
Total airframe hrs:11658 hours
Engine model:Allison 250-C20
Fatalities:Fatalities: 0 / Occupants: 2
Aircraft damage: Substantial
Category:Accident
Location:Fairbanks, AK -   United States of America
Phase: En route
Nature:Unknown
Departure airport:(KFAI)
Destination airport:Tok, AK (TKJ)
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
THE STATE OF ALASKA HELICOPTER EXPERIENCED A FUEL LEAK AND AN UNEVENTFUL PRECAUTIONARY LANDING. THE LEAKING FUEL LINE WAS REPLACED IN FIELD MAINTENANCE WITHOUT MANUFACTURER'S REQUIRED SECURING CLAMPS. A SECOND FUEL LEAK, PRECAUTIONARY LANDING AND FUEL LINE REPLACEMENT WAS EFFECTED, AGAIN WITHOUT CLAMPS. A THIRD FUEL LEAK AT THE SAME REPLACEMENT LINE WAS FOLLOWED BY A FIRE FOLLOWING A PRECUATIONARY LANDING. THE NTSB SUPERVISED MANUFACTURER'S ENGINE EXAMINATION REVEALED VIBRATION IN ROTATING COMPONENTS OF 15 TIMES THE ALLOWED LIMITS, AS WELL AS A FATIGUE CRACK IN THE HOT SECTION. THESE VIBRATIONS AND CRACKS WERE NOT DISCOVERED DURING ENGINE MAINTENANCE AND INSPECTIONS BY COMPANY CONTRACT MAINTENANCE PERSONNEL. THE METALLURGICAL EXAMINATION OF THE FUEL LINES IN EACH EVENT REVEALED FATIGUE PROPAGATION AND THE LACK OF CLAMP MARKS ON THE FUEL LINES FROM EVENTS 2 AND 3.

Probable Cause: POOR MAINTENANCE AND INSPECTION PROCEDURES BY THE CONTRACT MAINTENANCE PERSONNEL, AS WELL AS IMPROPER MAINTENANCE AND INSTALLATION OF THE FUEL LINE BY THE CONTRACT MAINTENANCE PERSONNEL. FACTORS RELATING TO THE ACCIDENT WERE THE TURBOSHAFT ENGINE VIBRATIONS AND THE CRACKED FUEL LINE(S).

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: ANC92GA155
Status: Investigation completed
Duration: 1 year
Download report: Final report

Sources:

NTSB ANC92GA155

Location

Revision history:

Date/timeContributorUpdates
18-Mar-2024 12:57 ASN Update Bot Added

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