ASN Wikibase Occurrence # 31087
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| Date: | Wednesday 16 April 1997 |
| Time: | 15:50 LT |
| Type: |  Bell 204B |
| Owner/operator: | U.s. Forest Svc./state Of Tn. |
| Registration: | N4580Y |
| MSN: | 2066 |
| Year of manufacture: | 1967 |
| Total airframe hrs: | 6645 hours |
| Engine model: | Lycoming T-53 |
| Fatalities: | Fatalities: 0 / Occupants: 1 |
| Aircraft damage: | Destroyed |
| Category: | Accident |
| Location: | near Calderwood, TN -
 United States of America
|
| Phase: | Unknown |
| Nature: | Unknown |
| Departure airport: | Copperhill, TN (1A3) |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
The main drive failed at the transmission end resulting in loss of transmission drive. The pilot performed a autorotation landing in trees and the helicopter rolled inverted and descended through the trees coming to rest on a river bank. Metallurgical examination showed the main drive shaft teeth had separated at the transmission end due to wear from frictional overheating which is a result of loss of lubrication. The helicopter manufacturer instructions require that the main drive shaft be inspected by a mechanic for loss of lubrication and signs of overheating during a daily inspection before the first flight of each day. The operator did not have records to show that the daily inspection had been performed prior to the accident flight.
Probable Cause: The inadequate maintenance inspection of the helicopter resulting in loss of lubrication from the main drive shaft going undetected until failure of the drive shaft.
Accident investigation:
 |
|
Sources:
NTSB MIA97TA139
History of this aircraft
Other occurrences involving this aircraft
| 29 July 1987 | N4580Y | Bill Williams-southern Aero | 0 | Dubois, WY | |
sub |
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 27-Sep-2008 01:00 | ASN archive | Added |
| 17-Jan-2009 11:21 | harro | Updated |
| 25-Feb-2020 07:35 | samfulton08 | Updated [Narrative] |
| 08-Apr-2024 15:57 | ASN Update Bot | Updated [Time, Operator, Other fatalities, Nature, Departure airport, Source, Narrative, Category, Accident report] |
Corrections or additions? ... Edit this accident description
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