# AD 49-47-02: Tail Rotor Drive Shaft

- Type: Airworthiness directive
- Status: Current
- Products: Scotts-Bell 47 47B, 47B3, 47D and 47D1
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Rotorcraft
- Registered aircraft: 54 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/7277BB8B87908C6286256A34004E7026.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/49-47-02

## The airworthiness directive

49-47-02 BELL: Applies to All Models 47B, 47B3, 47D, and Model 47D1 Serial Numbers 145 Through 164.

Compliance as indicated.

As a result of recent failures occurring to the tail rotor drive system the following inspections and replacements must be accomplished:

1. Not later than the next 25 hours of operation and at each 50-hour period thereafter the following inspection procedure must be accomplished until the tail rotor drive shaft parts as described below are incorporated:

  (a) Remove and disassemble tail boom extension for complete inspection.

  (b) Visually inspect bearings for wear, cracks, chips, and brinelling.

  (c) Inspect surfaces of shaft for dents, cuts, and signs of fatigue.

  (d) Conduct a magnaflux inspection of the tail boom extension drive shaft, examining particularly the shaft surface for approximately 3 inches of length from each end of the shaft.

  (e) Magnaflux 47-644-C14 sleeve inspecting for cracks at thread roots closestto flange.

2. To compensate for shaft misalignment and flight distortion of the shaft assembly, the following modifications shall be accomplished not later than February 15, 1950:

  (a) Installation of a redesigned extension drive shaft P/N 47-644-126 and 47- 644-181.

  (b) Installation of a spline coupling in tail rotor drive shaft forward of the universal joint P/N 47-644-177 and 47-644-130.

(Bell Service Bulletin No. 69, dated November 11, 1949, covers this subject.)

## Affected data sheets (1) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS H-1](https://openairdocs.org/tcds/H-1): Scott's-Bell 47 Inc; names 4 of 9 models: 47B, 47B3, 47D1, 47D

## Registered aircraft it may apply to (OpenAirDocs)

Matched by airframe and engine model; the AD's applicability may narrow it by serial number, part number or equipment.

- Aircraft: 54 (54 by airframe model, 0 by engine model)
- Makers: Bell 52, Bell Kitz Kopters 1, Bell-Allied Helicopter 1

Models with the most aircraft:

- [Bell 47D1](https://openairdocs.org/model/bell-47d1): 47 aircraft (airframe model)
- [Bell 47D](https://openairdocs.org/model/bell-47d): 4 aircraft (airframe model)
- [Bell 47B](https://openairdocs.org/model/bell-47b): 1 aircraft (airframe model)
- [Bell Kitz Kopters 47D1](https://openairdocs.org/model/bell-kitz-kopters-47d1): 1 aircraft (airframe model)
- [Bell-Allied Helicopter 47D1](https://openairdocs.org/model/bell-allied-helicopter-47d1): 1 aircraft (airframe model)

All 5 models: https://openairdocs.org/ad/49-47-02/models.md
Every aircraft: https://openairdocs.org/ad/49-47-02/aircraft.md

Its text cites no advisory circulars or STCs.

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