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ASN Wikibase Occurrence # 42587
Last updated: 4 December 2019
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Date:11-JUN-1985
Time:12:00
Type:Silhouette image of generic UH1 model; specific model in this crash may look slightly different
Bell UH-1B
Owner/operator:Temsco Helicopters
Registration: N99676
C/n / msn: 63-8513
Fatalities:Fatalities: 1 / Occupants: 1
Other fatalities:0
Aircraft damage: Written off (damaged beyond repair)
Category:Accident
Location:Juneau, AK -   United States of America
Phase: Landing
Nature:Unknown
Departure airport:Juneau, AK (JNU)
Destination airport:
Investigating agency: NTSB
Narrative:
WHILE ENGAGED IN A LOG SLINGING OPERATION OVER MOUNTAINOUS, DENSELY FORESTED TERRAIN THE ROTOR CRAFT SUFFERED A TOTAL POWER LOSS FORCING THE PILOT TO EXECUTE AN AUTOROTATIVE LANDING INTO HIGH CONIFER TREES. DISASSEMBLY OF THE ENGINE REVEALED EVIDENCE THAT THE SPACER BETWEEN THE NO. 5 COMPRESSOR AND THE IMPELLER HAD NOT BEEN POSITION SEATED DURING THE LAST OVERHAUL AND THAT DURING THE ACCIDENT FLIGHT THE SPACER SLIPPED INTO ITS PROPER POSITION THUS RELEASING THE COMPRESSIVE TORQUE LOAD UNDER WHICH THE ASSEMBLY HAD BEEN SUFJECTED DURING BUILDIP. THE COMPRESSOR ASSEMBLY SUBSEQUENTLY BECAME UNCOUPLED FORCING THE IMPELLER FORWARD INTO ITS MAGNESIUM HOUSING. THIS ACTION RESULTED IN AN OVERTEMPERATURE CONDITION AND BREAKUP WITHIN THE TURBINE ASSEMBLY BROUGHT ON BY THE COMBUSTION OF MAGNESIUM PARTICLES. CAUSE:

Sources:

NTSB: http://www.ntsb.gov/ntsb/brief.asp?ev_id=20001214X36910


Revision history:

Date/timeContributorUpdates
24-Oct-2008 10:30 ASN archive Added
21-Dec-2016 19:24 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]

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