ASN Wikibase Occurrence # 135327
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| Date: | Friday 4 July 2003 |
| Time: | 08:50 |
| Type: |  Sikorsky UH-19D |
| Owner/operator: | Americopter Aviation Services |
| Registration: | N37799 |
| MSN: | 56-1542 |
| Engine model: | Curtis Wright R1300-3D |
| Fatalities: | Fatalities: 0 / Occupants: 1 |
| Aircraft damage: | Destroyed |
| Category: | Accident |
| Location: | La Grande, OR -
 United States of America
|
| Phase: | Manoeuvring (airshow, firefighting, ag.ops.) |
| Nature: | Agricultural |
| Departure airport: | La Grande, OR (LGD) |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
During an aerial application flight, the pilot reported that during a turn he heard and felt three or four "clunking sounds in the airframe." The pilot continued the pedal turn to the left and then straightened out to approach a field. Rotor rpm was deteriorating as he attempted to auto rotate to the field. The pilot stated that he had "no auto-rotating capability" and landed hard in the field. The helicopter bounced once then touched down again coming to rest on its left side. A post-crash fire consumed the wreckage. On site inspection of the wreckage found that the free wheeling side of the clutch assembly and the main drive shaft assembly nut were disconnected. The items were sent to the NTSB materials laboratory for further inspection. The specialist reported that the drive from the main rotor gearbox to the clutch was severed when the bearing support separated from the drive housing. The threads on the bearing support displayed a shearing off of the crown of the forward full form thread. The flanks of the threads to the rear of the sheared thread displayed no indications of contact by the mating thread on the drive housing. Mechanical damage to the threads on the drive housing was limited to the first two rearmost threads. The flanks of the threads forward of the damaged threads displayed no indications of contact by the mating thread on the bearing support. Deformation of the rear ends of the splines forward of the threads and of the two rearmost threads indicate that it was not fully engaged with the drive housing.
Probable Cause: The cross threading and separation of the clutch assembly while maneuvering which resulted in a loss of engine power followed by a hard landing. An inadequate maintenance overhaul was a factor.
Accident investigation:
 |
|
Sources:
NTSB: https://www.ntsb.gov/_layouts/ntsb.aviation/brief.aspx?ev_id=20030714X01097&key=1
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 21-Dec-2016 19:26 | ASN Update Bot | Updated [Time, Damage, Category, Investigating agency] |
| 08-Dec-2017 18:56 | ASN Update Bot | Updated [Other fatalities, Departure airport, Source, Narrative] |
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