ASN Wikibase Occurrence # 357585
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| Date: | Thursday 4 April 1996 |
| Time: | 10:20 LT |
| Type: |  Bell UH-1H |
| Owner/operator: | Northwest Helicopters, Inc. |
| Registration: | N6166R |
| MSN: | 157199 |
| Year of manufacture: | 1995 |
| Total airframe hrs: | 5020 hours |
| Engine model: | Lycoming T53-L-13BA |
| Fatalities: | Fatalities: 0 / Occupants: 1 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Rainier, WA -
 United States of America
|
| Phase: | Manoeuvring (airshow, firefighting, ag.ops.) |
| Nature: | Unknown |
| Departure airport: | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
While preparing to sling a load of logs, the pilot noticed several changes in engine noise level followed by two loud bangs and a total loss of power. He executed an autorotation/landing into a small clearing directly beneath the rotorcraft as no other suitable site was available. During the forced landing, the helicopter was damaged. Disassembly of the ex-military, Allied Signal (Lycoming) T53-L-13BA turboshaft engine revealed that the number 21 forward bearing (P/N 1-300-082-01B) had disintegrated. The engine had a total of 4202.4 operating hours of which 199.4 were accrued since entering the civilian operating environment. Nonmandatory Service Bulletin No. 0056 provided procedures for replacing this bearing with an improved bearing (P/N 1-300-082-03), within 400 hours after receipt of the bulletin.
Probable Cause: failure of the forward power shaft (number 21) bearing. A factor relating to the accident was: the lack of suitable, unobstructed terrain for an emergency landing.
Accident investigation:
 |
|
Sources:
NTSB SEA96FA076
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 13-Mar-2024 19:28 | ASN Update Bot | Added |
Corrections or additions? ... Edit this accident description
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