# AD 74-10-04: Main Gearbox

- Type: Airworthiness directive
- Status: Current
- Products: Pratt & Whitney Division JT9D-3A and JT9D-7
- Effective: May 14, 1974
- Superseded by: Nothing supersedes this AD
- Product type: Engine
- Amendment: 39-1831
- Registered aircraft: 18 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/6CCED2657928BF018625685B0068E98B.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/74-10-04

## The airworthiness directive

74-10-04 PRATT & WHITNEY: Amendment 39-1831. Applies to all Pratt & Whitney Model JT9D-3A and JT9D-7 turbofan engines.

Compliance required not later than February 1, 1975.

1. To prevent the possibility of internal main gearbox fires in the event of an internal gearbox failure, rework the main gearbox in accordance with Pratt & Whitney Service Bulletin No. 4043, dated February 5, 1973, or later Federal Aviation Administration approved revisions.

2. To prevent leakage of oil around carbon face seals, replace present seal assemblies with the redesigned carbon face seal assemblies per Pratt & Whitney Service Bulletin No. 3902, dated August 8, 1972, or later Federal Aviation Administration approved revisions or Federal Aviation Administration approved equivalent.

3. Equivalent methods of compliance to the requirements of paragraph 2 above must be approved by the Chief, Engineering and Manufacturing Branch, Federal Aviation Administration, New England Region.

Themanufacturer's specifications and procedures identified and described in this directive are incorporated herein and made a part hereof pursuant to 5 U.S.C. 552(a)(1). All persons affected by this directive who have not already received these documents from the manufacturer may obtain copies upon request to the Chief Engineer, Pratt and Whitney Aircraft, Division of United Aircraft Corporation, 400 Main Street, East Hartford, Connecticut 06108. These documents may also be examined at the Office of the Regional Counsel, New England Region, FAA, 12 New England Executive Park, Burlington, Massachusetts 01803 and at FAA Headquarters, 800 Independence Avenue, S. W., Washington, D. C. A historical file on this AD which includes the incorporated material in full is maintained by the FAA at its headquarters in Washington, D. C., and at the New England Regional Office in Burlington, Massachusetts.

This amendment becomes effective May 14, 1974.

## Affected data sheets (1) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS E20EA](https://openairdocs.org/tcds/E20EA): Pratt & Whitney; names 2 of 9 models: JT9D-7, JT9D-3A

## 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: 18 (0 by airframe model, 18 by engine model)
- Makers: Boeing 14, Airbus Industrie 2, Douglas 1, Mcdonnell Douglas 1

Models with the most aircraft:

- [Pratt & Whitney JT9D series](https://openairdocs.org/engine/pratt-whitney-jt9d-series): 13 aircraft (engine model)
- [Pratt & Whitney JT9D-3A](https://openairdocs.org/engine/pratt-whitney-jt9d-3a): 4 aircraft (engine model)
- [Pratt & Whitney JT9D-7](https://openairdocs.org/engine/pratt-whitney-jt9d-7): 1 aircraft (engine model)

All 3 models: https://openairdocs.org/ad/74-10-04/models.md
Every aircraft: https://openairdocs.org/ad/74-10-04/aircraft.md

Its text cites no advisory circulars or STCs.

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