ASN Wikibase Occurrence # 175341
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| Date: | Saturday 28 February 2004 |
| Time: | 14:00 |
| Type: |  Schweizer 269C |
| Owner/operator: | Private |
| Registration: | N75070 |
| MSN: | 1404 |
| Total airframe hrs: | 4811 hours |
| Engine model: | Lycoming HIO-360 |
| Fatalities: | Fatalities: 0 / Occupants: 1 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Media, PA -
 United States of America
|
| Phase: | Landing |
| Nature: | Training |
| Departure airport: | Medford, NJ (VAY) |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
The student pilot was flying the helicopter in cruise flight, at 800 feet, when a loss of tail rotor thrust occurred, with a "sharp metallic-sounding squeal." The student pilot then performed an autorotation which resulted in a hard landing. Examination of the tail rotor drive shaft, forward fitting teeth, revealed smearing and rubbing in the middle of the tooth surfaces. A wear/rubbing failure mechanism had been previously seen on other helicopters, that resulted from insufficient lubrication. Although the forward fitting had a significant amount of grease on it, it could not be confirmed whether grease had always been present. No significant manufacturing defects were found. With over 3,000 helicopters in service, only two similar events had been attributed to insufficient lubrication, and both occurred on same helicopter model within the previous year. Shaft loading, which was "relatively light," only required minimal lubrication to a design that had remained essentially unaltered since the 1960s. The shaft, which required an inspection every 300 hours, had last been inspected 180 hours before the accident.
Probable Cause: A lack of previous lubrication to the tail rotor drive shaft forward fitting teeth, which resulted in their gradual wear, the eventual slippage of the shaft, and the subsequent loss of tailrotor thrust and forced landing.
Accident investigation:
 |
|
Sources:
NTSB: https://www.ntsb.gov/_layouts/ntsb.aviation/brief.aspx?ev_id=20040307X00288&key=1
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 12-Apr-2015 21:37 | Noro | Added |
| 21-Dec-2016 19:30 | ASN Update Bot | Updated [Time, Damage, Category, Investigating agency] |
| 07-Dec-2017 17:41 | ASN Update Bot | Updated [Cn, Other fatalities, Nature, Departure airport, Source, Narrative] |
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