# AD 72-25-04: Loss of Main Rotor Control

- Type: Airworthiness directive
- Status: Current
- Products: Sikorsky S-61A, S-61D, S-61L, S-61N, S-61R and S-61V
- Effective: December 15, 1972
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Rotorcraft
- Amendment: 39-1571
- Registered aircraft: 53 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/E337E55733CC6B9086256A5600445591.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/72-25-04

## The airworthiness directive

72-25-04 SIKORSKY: Amdt. 39-1571. Applies to all Sikorsky S-61A, S-61B, S-61D, S- 61L Series prior to SS No. 61454, S-61N Series prior to SS No. 61493, S-61R, S-61V helicopters certificated in all categories.

Compliance required as indicated.

To prevent hazards in flight due to loss of main rotor control as a result of cracked primary servo mounting bracket retaining nuts, accomplish the following:

  (a) Within the next 25 hours time in service after the effective date of this Airworthiness Directive, remove all MS21042-6 or MS20365-624C retaining nuts from the primary servo mounting brackets, P/N S613520249, and replace with P/N MS21045-6 retaining nuts in accordance with Sikorsky Service Bulletin No. 61B35-18 dated 10 November 1972 or later revision approved by the Chief, Engineering and Manufacturing Branch, FAA, New England Region.

  (b) Upon request with substantiation data submitted through an FAA maintenance inspector, the compliance time specified in this AD may be increased by the Chief, Engineering and Manufacturing Branch, FAA, New England Region.

  (c) Equivalent methods of compliance must be approved by the Chief, Engineering and Manufacturing Branch, FAA, New England Region.

This amendment becomes effective December 15, 1972.

## Affected data sheets (2) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS 1H15](https://openairdocs.org/tcds/1H15): Sikorsky Aircraft; names 3 of 4 models: S-61R, S-61N, S-61L
- [TCDS H2EA](https://openairdocs.org/tcds/H2EA): Sikorsky Aircraft Corporation; names 3 of 4 models: S-61A, S-61D, S-61V

## 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: 53 (53 by airframe model, 0 by engine model)
- Makers: Sikorsky 52, Carson Helicopters / Sikorsky 1

Models with the most aircraft:

- [Sikorsky S-61N](https://openairdocs.org/model/sikorsky-s-61n): 45 aircraft (airframe model)
- [Sikorsky S-61A](https://openairdocs.org/model/sikorsky-s-61a): 5 aircraft (airframe model)
- [Sikorsky S-61L](https://openairdocs.org/model/sikorsky-s-61l): 1 aircraft (airframe model)
- [Sikorsky S-61R](https://openairdocs.org/model/sikorsky-s-61r): 1 aircraft (airframe model)
- [Carson Helicopters / Sikorsky S61A](https://openairdocs.org/model/carson-helicopters-sikorsky-s61a): 1 aircraft (airframe model)

All 5 models: https://openairdocs.org/ad/72-25-04/models.md
Every aircraft: https://openairdocs.org/ad/72-25-04/aircraft.md

Its text cites no advisory circulars or STCs.

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