ASN Wikibase Occurrence # 296573
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| Date: | Sunday 29 September 2002 |
| Time: | 07:54 LT |
| Type: |  Eurocopter AS350-B3 |
| Owner/operator: | U.S. Forest Service |
| Registration: | N352SA |
| MSN: | 3348 |
| Year of manufacture: | 2000 |
| Total airframe hrs: | 736 hours |
| Engine model: | Turbomeca Arriel 1D1 |
| Fatalities: | Fatalities: 0 / Occupants: 4 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Bishop, CA -
 United States of America
|
| Phase: | Unknown |
| Nature: | Unknown |
| Departure airport: | Bishop Airport, CA (BIH/KBIH) |
| Bridgeport, CA (O57) | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
The helicopter was performing a hydraulic actuator check for the first flight of the day. The collective had been placed in the down position, the collective lock was engaged, and the rotor powered up to 100 percent flight idle. After depressing the hydraulic test switch, the pilot moved the cyclic fore and aft to confirm there was pressure remaining in the accumulators for a few control movements. The collective rose uncommanded and the helicopter moved forward in a nose down attitude. The main rotor struck the ground and the helicopter made two revolutions before rolling over onto its side, destroying both the main and tail rotor systems. A small fire ensued in the exhaust area, but was quickly extinguished. Examination of the collective locking mechanism (P/N 350A-27 3455-20 and P/N 350A-27 3107-26) found that it failed to hold the collective in the full down position due to wear on the locking tab. During servo accumulator checks, movement of the cyclic control after accumulator depletion caused the collective to move due to feedback in the control system. The locking device disengaged and the collective increased causing the aircraft to move.
Probable Cause: the disengagement of the collective locking mechanism due to component wear.
Accident investigation:
 |
|
Sources:
NTSB LAX02TA299
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 14-Oct-2022 08:11 | ASN Update Bot | Added |
| 12-Nov-2022 02:24 | Ron Averes | Updated [Operator, Location, Narrative] |
Corrections or additions? ... Edit this accident description
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