ASN Wikibase Occurrence # 355564
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| Date: | Sunday 13 July 1997 |
| Time: | 05:50 LT |
| Type: |  Bell 47G-3B-1 |
| Owner/operator: | Private |
| Registration: | N83701 |
| MSN: | 3835 |
| Total airframe hrs: | 5175 hours |
| Engine model: | Lycoming VO-435 |
| Fatalities: | Fatalities: 0 / Occupants: 1 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Crossett, AR -
 United States of America
|
| Phase: | Landing |
| Nature: | Ferry/positioning |
| Departure airport: | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
The pilot (plt) said that during flight, he 'heard and felt flutter in the tail rotor.' He began an emergency descent, & about 25' above power lines, the helicopter (hel) began yawing (spinning) to the right. After 7 to 9 'revolutions,' the plt 'pulled pitch' to cushion impact. The hel landed hard in a ditch & was damaged (fuselage was bent & tail boom was twisted). An exam revealed the forward portion of the tail rotor drive shaft was disconnected from the transmission. The disconnect was due to an increase in distance between the forward & aft female couplings of the shaft. The increased distance was due to a fractured longeron tube on the upper left side of the fuselage center frame. The tube extended aft from airframe station -2.0 (where the left side engine Lord mount was bolted to the center frame) to the tube cluster at station -50.99. The fracture was not readily visible due to the tube's location behind a crop-spraying tank. Further exam revealed the crack was due to fatigue that originated at the toe of a weld for a gusset. Heavy corrosion & pitting on the fracture surface suggested the crack had been developing for some time. Records showed the center frame was manufactured as part of the hel; the hel was originally delivered as a U.S. Army TH-13T on 10/31/68.
Probable Cause: failure of maintenance personnel to perform an adequate inspection of the fuselage center frame and detect a fatigue fracture of a longeron tube on the upper left side of the center frame, which resulted in a disconnect of the tail rotor drive shaft from the transmission, loss of yaw (anti-torque) control, and a subsequent hard (emergency) landing. A related factor was the lack of suitable terrain for a forced landing.
Accident investigation:
 |
|
Sources:
NTSB FTW97LA264
History of this aircraft
Other occurrences involving this aircraft
| 16 July 2000 | N83701 | Sky Tractor, Inc. | 0 | HOLSTEIN, Nebraska | |
sub |
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 12-Mar-2024 13:20 | ASN Update Bot | Added |
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