ASN Wikibase Occurrence # 46013
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| Date: | Wednesday 7 February 2001 |
| Time: | 14:00 |
| Type: | Western International UH-1H |
| Owner/operator: | Grim Logging Co., Inc. |
| Registration: | N205GL |
| MSN: | 74-22356 |
| Year of manufacture: | 1974 |
| Total airframe hrs: | 11387 hours |
| Engine model: | Lycoming T53-L-13B |
| Fatalities: | Fatalities: 1 / Occupants: 1 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Darby, MT -
 United States of America
|
| Phase: | Unknown |
| Nature: | External load operation |
| Departure airport: | Darby, MT |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
The pilot was on the last half of his first external load of the afternoon when he reported over the radio, " tail rotor failure, look out landing" (referring to the log landing crew.) The pilot released his logs from the lower hook, but retained his 150-foot line. He flew over the log landing to regain airspeed, but the helicopter's long line then snagged a tree on the far side of the landing, causing the aircraft to roll left and pitch nose down. The aircraft impacted the ground 250 feet from the snagged tree, nose low, with between 100 and 130 degrees of left roll, landing on the top left crew door post. During post-accident examination, one of the pitch links on the tail rotor hub was found disconnected from the pitch horn on the tail rotor grip. The attaching bolt, nut, cotter key and washers associated with the disconnected tail rotor pitch link were missing and were not located. No other evidence of inflight malfunction of the tail rotor drive train or tail rotor control system was noted. Examination of the tail rotor pitch change links and blade grip horns at the NTSB Materials Laboratory disclosed evidence of a complete loss of the pitch change link-to-blade grip horn attach bolt before ground impact, as a result of either its nut backing off inflight or of the bolt itself fracturing inflight.
Probable Cause: Inflight loss of a tail rotor pitch change link-to-blade grip attach bolt, resulting partial loss of tail rotor control, and subsequent entanglement of the helicopter's external load cable with a tree during emergency descent. Factors included the pilot's retention of external load equipment, and the tree in which the external load cable became entangled.
Accident investigation:
 |
|
Sources:
NTSB: https://www.ntsb.gov/_layouts/ntsb.aviation/brief.aspx?ev_id=20010226X00511&key=1
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 28-Oct-2008 00:45 | ASN archive | Added |
| 21-Dec-2016 19:24 | ASN Update Bot | Updated [Time, Damage, Category, Investigating agency] |
| 10-Dec-2017 10:32 | ASN Update Bot | Updated [Operator, Nature, Source, Narrative] |
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