# AD 89-07-09: Main Rotor Gearbox

- Type: Airworthiness directive
- Status: Current
- Products: Sikorsky S-61A, S-61D, S-61E, S-61L, S-61N, S-61NM, S-61R and S-61V
- Effective: April 20, 1989
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Rotorcraft
- Amendment: 39-6172
- Docket: 89-ASW-4
- Registered aircraft: 54 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/E677197E212950A186256A4D0074648E.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/89-07-09

## The airworthiness directive

89-07-09 SIKORSKY AIRCRAFT: Amendment 39-6172.

Applicability: All Model S-61 series helicopters, certificated in any category, equipped with main rotor gearbox helical gear Part Number S6135-20620-003, Serial Numbers 1086, 1087, 1089, and 1090 through and including 1099, 1101, 1103, through and including 1113, 1116, 1117, 1130, 1132. (Docket No. 89-ASW-4).

Compliance: Required within the next 100 hours' time in service, unless already accomplished.

To prevent possible failure of the helical gear, accomplish the following:

  (a) Inspect the main rotor gearbox to identify the serial number of the helical gear installed. If the helical gear is identified with a serial number listed in this AD, replace it with an airworthy helical gear which has a serial number other than listed in this AD.

NOTE: Sikorsky Aircraft message CBT-TS-89-002 dated January 23, 1989, applies to this AD.

  (b) Aircraft may be ferried in accordance with the provisions of FAR Sections 21.197 and 21.199 to a base where the provisions of the AD can be accomplished.

  (c) An alternate means of compliance or an adjustment of the initial compliance time which provides an equivalent level of safety may be used if approved by the Manager, Boston Aircraft Certification Office, Federal Aviation Administration, 12 New England Executive Park, Burlington, MA 01803.

The noted service information may be obtained from Sikorsky Aircraft, 6900 Main Street, Mail Stop S409A, Stratford, CT 06601-1381.

This amendment (39-6172, AD 89-07-09) becomes effective on April 20, 1989.

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

## 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: Sikorsky 53, 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-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)
- [Carson Helicopters / Sikorsky S61A](https://openairdocs.org/model/carson-helicopters-sikorsky-s61a): 1 aircraft (airframe model)

All 6 models: https://openairdocs.org/ad/89-07-09/models.md
Every aircraft: https://openairdocs.org/ad/89-07-09/aircraft.md

Its text cites no advisory circulars or STCs.

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