# AD 76-03-02: Fractures in Barrel Nuts

- Type: Airworthiness directive
- Status: Current
- Products: Sikorsky S-61L, S-61N, S-61NM and S-61R
- Effective: February 17, 1976
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Rotorcraft
- Amendment: 39-2507
- Registered aircraft: 48 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/9D142C5DEF88C49E86256A5600473A10.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/76-03-02

## The airworthiness directive

76-03-02 SIKORSKY AIRCRAFT: Amendment 39-2507. Applies to S-61L, S-61N, S- 61NM, and S-61R helicopters certified in all categories including Military CH-3C, HH-3C, CH- 3E, and HH-3E helicopters using NAS 577-10 or NAS 577-10A barrel nuts for attaching the transmission main gearbox to the fuselage structure.

Compliance required as indicated.

To prevent fractures in the attaching nuts accomplish the following:

Remove the NAS 577-10 or NAS 577-10A barrel nuts and replace with RMLH 2577-108 barrel nuts within the next 30 days after the effective date of this AD, unless already accomplished. (NOTE: Sikorsky Service Bulletin No. 61B35-36B covers this subject.)

This supersedes Amendment 39-2202 (40 FR 24355), AD 75-12-13.

This amendment becomes effective February 17, 1976.

## Affected data sheets (1) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS 1H15](https://openairdocs.org/tcds/1H15): Sikorsky Aircraft; names 4 of 4 models: S-61R, S-61N, S-61L, S-61NM

## 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: 48 (48 by airframe model, 0 by engine model)
- Makers: Sikorsky 48

Models with the most aircraft:

- [Sikorsky S-61N](https://openairdocs.org/model/sikorsky-s-61n): 45 aircraft (airframe model)
- [Sikorsky S-61L](https://openairdocs.org/model/sikorsky-s-61l): 1 aircraft (airframe model)
- [Sikorsky S-61NM](https://openairdocs.org/model/sikorsky-s-61nm): 1 aircraft (airframe model)
- [Sikorsky S-61R](https://openairdocs.org/model/sikorsky-s-61r): 1 aircraft (airframe model)

All 4 models: https://openairdocs.org/ad/76-03-02/models.md
Every aircraft: https://openairdocs.org/ad/76-03-02/aircraft.md

Its text cites no advisory circulars or STCs.

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