# AD 74-15-05: Compressor Discs

- Type: Airworthiness directive
- Status: Current
- Products: Pratt & Whitney Division JT3D-1, JT3D-1-MC6, JT3D-1-MC7, JT3D-1A, JT3D-1A-MC6, JT3D-1A-MC7, JT3D-3, JT3D-3B, JT3D-3C, JT3D-5A, JT3D-7 and JT3D-7A
- Effective: July 25, 1974
- Superseded by: Nothing supersedes this AD
- Product type: Engine
- Amendment: 39-1898
- Registered aircraft: 5 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/0301340F3602851C8625685B006DE2A0.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/74-15-05

## The airworthiness directive

74-15-05 PRATT & WHITNEY: Amendment 39-1898. Applies to all Pratt & Whitney Aircraft JT3D turbofan engines containing 14th stage compressor disc, P/N 657814.

Compliance required as indicated.

To ensure adequate life limit margin for 14th stage compressor discs, P/N 657814, the cyclic life limits on these discs have been reduced below the figures currently approved. Unless already accomplished, remove from service 14th stage compressor discs prior to exceeding the revised life limit listed below or within the next 25 cycles in service after the effective date of this airworthiness directive whichever comes later.

Engine Model Previous Life Limit (Cycles) Revised Life Limit (Cycles) JT3D-1 19,000 10,000 JT3D-3B 15,000 8,000 JT3D-7 15,000 8,000

If a disc has been used in more than one engine model, the disc is limited to the lowest cycle life permitted for the engine models in which it has been exposed.

This amendment becomes effective July25, 1974.

## Affected data sheets (2) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS 1E8](https://openairdocs.org/tcds/1E8): Pratt & Whitney Division; names 11 of 11 models: JT3D-3, JT3D-3C, JT3D-1A-MC7, JT3D-1-MC6, JT3D-7, JT3D-1-MC7, JT3D-1A, JT3D-3B…
- [TCDS E3EA](https://openairdocs.org/tcds/E3EA): Pratt & Whitney Division; names 1 of 3 models: JT3D-5A

## 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: 5 (0 by airframe model, 5 by engine model)
- Makers: Boeing 3, Mcdonnell Douglas 2

Models with the most aircraft:

- [Pratt & Whitney JT3D-3B](https://openairdocs.org/engine/pratt-whitney-jt3d-3b): 3 aircraft (engine model)
- [Pratt & Whitney JT3D series](https://openairdocs.org/engine/pratt-whitney-jt3d-series): 2 aircraft (engine model)

All 2 models: https://openairdocs.org/ad/74-15-05/models.md
Every aircraft: https://openairdocs.org/ad/74-15-05/aircraft.md

Its text cites no advisory circulars or STCs.

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