# AD 57-12-03: Engine Sprag Spindle

- Type: Airworthiness directive
- Status: Current
- Products: Scotts-Bell 47 47J
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Rotorcraft
- Registered aircraft: 6 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/B66E4E93E122D8DF86256A340050AEBD.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/57-12-03

## The airworthiness directive

57-12-03 BELL: Applies to Model 47J Helicopters Serial Numbers 1420 Through 1426, 1429 Through 1433, 1435 Through 1439, and 1441, 1559, 1562, 1574.

Compliance required prior to July 1, 1957.

In order to preclude the failure of the engine sprag spindle P/N 47-612-167-1, due to overtorquing of the AN 320-10 nut, the following modification must be accomplished.

1. Remove spindle after first removing the 47-612-166 links from the spindle and 47-612-158 brace assemblies.

2. Install one AN 6-17 bolt with one AN 960-616L washer under the head in the spindle.

3. Reinstall the previously removed links on the spindle. Drill a No. 52 (.062 dia.) hole in one castellation of the AN 320-10 nut for safety wire. Reinstall an AN 960-1016 washer and AN 320-10 nut. After positioning links, torque AN 320-10 nut to 150 inch-pounds.

(NOTE: One AN 364-1018 nut may be substituted for the drilled AN 320-10 nut.)

4. Install one AN 960-616L washer and one AN 310-6 nut on end of AN 6-17 bolt. Torque to 160-190 inch-pounds and install one AN 381-3-12 cotter key.

5. Replace spindle. Resafety attach bolts and safety AN 320-10 nut (if used) to the spindle attach bolts.

6. Connect the links, using previously removed hardware.

(Bell Mandatory Service Bulletin No. 120 dated March 29, 1957, covers this same subject.)

## Affected data sheets (1) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS 2H1](https://openairdocs.org/tcds/2H1): Scott's-Bell 47 Inc; names 1 of 4 models: 47J

## 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: 6 (6 by airframe model, 0 by engine model)
- Makers: Bell 6

Models with the most aircraft:

- [Bell 47J](https://openairdocs.org/model/bell-47j): 6 aircraft (airframe model)

All 1 models: https://openairdocs.org/ad/57-12-03/models.md
Every aircraft: https://openairdocs.org/ad/57-12-03/aircraft.md

Its text cites no advisory circulars or STCs.

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