Bell 47G-3B-1 N83701

Summary

On 13 July 1997 at about 10:50 local time, a Bell 47G-3B-1 registered N83701 was involved in an accident near Crossett, Arkansas, United States. One person was on board and one was seriously injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

13 July 1997 at 10:50

Classification

Accident

Location

Crossett, Arkansas, United States

Coordinates

33.1196, -91.9596

Aircraft

Bell 47G-3B-1

Registration

N83701

Category

Helicopter

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Positioning

Phase of flight

Not recorded

Aircraft damage

Substantial

Weather

VMC

Light

Dawn

NTSB number

FTW97LA264

1 person was seriously injured.

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.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

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.

Quoted verbatim from the NTSB record.