# AD 74-22-01: Engine Mounts

- Type: Airworthiness directive
- Status: Current
- Products: Boeing DC-9-11, DC-9-12, DC-9-13, DC-9-14, DC-9-15, DC-9-15F, DC-9-21, DC-9-31, DC-9-32, DC-9-32 (VC-9C), DC-9-32F, DC-9-32F (C-9A) and 5 more
- Effective: June 12, 1979
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Large airplane
- Amendment: 39-3487
- Registered aircraft: 13 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/8A57E928680BDF8F86256E0C0071FE83.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/74-22-01

## The airworthiness directive

74-22-01 MCDONNELL DOUGLAS: Amendment 39-1995, as amended by amendment 39-3487. Applies to all Model DC-9 -10, -20, -30, -40 and military C-9A and C-9B Series airplanes equipped with welded aft engine isolator mount(s), P/N K2219-6SA3, certificated in all categories.

To detect cracks in the welded aft engine mounts, accomplish the following:

For airplanes equipped with welded aft engine isolator mount(s) with more than 4,000 hours time-in-service on the effective date of this AD, within the next 300 hours time-in-service, unless previously accomplished within the last 450 hours time-in-service, and thereafter at intervals not to exceed 850 hours time-in-service, inspect the aft engine mount per McDonnell Douglas All Operators' Letter AOL 9-786, dated December 13, 1973, AOL 9-786A dated March 27, 1974, AOL 9-786B dated April 8, 1974, or an equivalent approved by the Chief, Aircraft Engineering Division, FAA Western Region. If any cracks are detected replace the part before further flight with a forged part, P/N's K2219-6SA5 and K2219-7SA3, or an uncracked welded part K2219-6SA3. Upon installation of a forged part the requirements of this A.D. are terminated.

NOTE: (A) For the purposes of this A.D. if the time-in-service hours of the aft engine isolator mount cannot be established the part will be considered to have the same number of time-in-service hours as the airplane on which it is installed.

      (B) The airplane may be flown in accordance with FAR's 21.197 21.199 to a base where the inspection can be performed.

Amendment 39-1995 became effective November 25, 1974.

This amendment 39-3487 becomes effective June 12, 1979.

## Affected data sheets (1) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS A6WE](https://openairdocs.org/tcds/A6WE): The Boeing Company; names 14 of 25 models: DC-9-12, DC-9-15F, DC-9-41, DC-9-13, DC-9-34F, DC-9-33F, DC-9-11, DC-9-31…

## 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: 13 (13 by airframe model, 0 by engine model)
- Makers: Mcdonnell Douglas 8, Douglas 5

Models with the most aircraft:

- [Mcdonnell Douglas DC-9-15F](https://openairdocs.org/model/mcdonnell-douglas-dc-9-15f): 3 aircraft (airframe model)
- [Mcdonnell Douglas DC-9-33F](https://openairdocs.org/model/mcdonnell-douglas-dc-9-33f): 3 aircraft (airframe model)
- [Douglas DC9-15](https://openairdocs.org/model/douglas-dc9-15): 1 aircraft (airframe model)
- [Douglas DC-9-15F](https://openairdocs.org/model/douglas-dc-9-15f): 1 aircraft (airframe model)
- [Douglas DC-9-21](https://openairdocs.org/model/douglas-dc-9-21): 1 aircraft (airframe model)
- [Douglas DC-9-32F](https://openairdocs.org/model/douglas-dc-9-32f): 1 aircraft (airframe model)
- [Mcdonnell Douglas DC-9-32](https://openairdocs.org/model/mcdonnell-douglas-dc-9-32): 1 aircraft (airframe model)
- [Mcdonnell Douglas DC-9-32F](https://openairdocs.org/model/mcdonnell-douglas-dc-9-32f): 1 aircraft (airframe model)
- [Douglas DC-9-33F](https://openairdocs.org/model/douglas-dc-9-33f): 1 aircraft (airframe model)

All 9 models: https://openairdocs.org/ad/74-22-01/models.md
Every aircraft: https://openairdocs.org/ad/74-22-01/aircraft.md

Its text cites no advisory circulars or STCs.

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