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ASN Wikibase Occurrence # 175980
Last updated: 8 February 2020
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Type:Silhouette image of generic UH1 model; specific model in this crash may look slightly different
Bell UH-1B
Registration: N46969
C/n / msn: 63-8548
Fatalities:Fatalities: 0 / Occupants: 1
Aircraft damage: Substantial
Location:Near Pierre Lake, Orient, Washington -   United States of America
Phase: Manoeuvring (airshow, firefighting, ag.ops.)
Departure airport:Kettle Falls, WA
Destination airport:Kettle Falls, WA
Investigating agency: NTSB
The commercial pilot was conducting an external load logging flight in the helicopter. A review of maintenance records revealed that, on the day of the accident, the engine had been replaced with an overhauled engine. Following the maintenance, the pilot completed one logging cycle without incident. The pilot reported that, about 50 minutes into the second cycle, she heard a loud screeching/grinding noise followed by a muffled “bang.” The low rotor rpm horn sounded, and she initiated an autorotation. The helicopter touched down, impacted trees, rolled down sloped terrain, and then came to rest.
A postaccident examination of the engine’s particle separator assembly revealed that it was intact and installed properly on the air inlet section; however, the inlet guide vanes exhibited signatures consistent with foreign object damage, and a material consistent with a towel was found within the vanes. Given the damage signatures and the found material, it is likely that maintenance personnel did not adequately inspect the engine area after installing the overhauled engine and left a towel in its compressor section, which the engine subsequently ingested and resulted in a total loss of power.

Probable Cause: A total loss of engine power due to foreign object (towel) ingestion. Contributing to the accident was maintenance personnel’s inadequate postmaintenance inspection of the engine.


FAA register:

Revision history:

08-May-2015 06:42 Iceman 29 Added
08-May-2015 06:43 harro Updated [Aircraft type, Total fatalities, Total occupants, Other fatalities, Location, Source, Damage, Narrative]
08-May-2015 16:52 Geno Updated [Aircraft type, Registration, Cn, Operator, Location, Phase, Nature, Source, Damage, Narrative]
07-Jun-2015 08:54 stevethehumbersider Updated [Cn, Narrative]
26-Jul-2015 16:42 Anon. Updated [Narrative]
21-Dec-2016 19:30 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]
01-Dec-2017 13:07 ASN Update Bot Updated [Cn, Operator, Other fatalities, Nature, Departure airport, Destination airport, Source, Narrative]

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