# AD 79-20-01: Aft Mount To Pylon Bulkhead Bolts

- Type: Airworthiness directive
- Status: Current
- Products: Boeing DC-10-10, DC-10-10F and DC-10-40
- Effective: November 1, 1979
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Large airplane
- Amendment: 39-3604
- Registered aircraft: 6 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/92392F3CC10BCD4486256E0C00739134.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/79-20-01

## The airworthiness directive

79-20-01 MCDONNELL DOUGLAS: Amendment 39-3575 as amended by Amendment 39-3604. Applies to McDonnell Douglas Model DC-10-10, -10F, and -40 Series airplanes certificated in all categories with more than 3,000 hours' total time in service.

Compliance required as indicated.

To prevent failures of the bolts attaching the aft engine mount to the pylon bulkheads of the Number 1, 2, and 3 engines on the DC-10-10 and -10F, and the Number 1 and Number 3 engines of the DC-10-40 airplanes accomplish the following, unless already accomplished subsequent to July 19, 1979, or unless the bolts have been replaced within the last 3,000 hours' time in service:

  (a) Before further flight, check the integrity of each of the four main aft mount to pylon bulkhead bolts, by applying heavy manual force using a box wrench approximately twelve inches long.

  (b) If there is any movement of the nut, the bolt must be removed and replaced with a serviceable bolt of the same part number or an FAA approved equivalent bolt, before further flight.

NOTE: Douglas Telex DC-10-COM47/HEW covers this same subject.

  (c) Within 600 hours' time in service after the effective date of this AD and thereafter at intervals not to exceed 3,600 hours' time in service, inspect the four main aft mount to pylon bulkhead bolts, in accordance with the nondestructive test procedures in McDonnell Douglas DC-10 Service Bulletin 54-72 dated 27 August 1979.

  (d) If there is a crack indication, before further flight, replace with a serviceable bolt of the same part number or an FAA approved equivalent bolt.

  (e) These special inspections may be discontinued and normal maintenance inspections resumed after installation of inconel bolts (77711-10-34 and 77711-8-21, Series 10) or (77711-12-34, Series 40).

  (f) Alternate inspections, modifications or other actions which provide an equivalent level of safety may be used when approved by the Chief, Aircraft Engineering Division, FAA Western Region.

  (g) Special flight permits may be issued in accordance with FARs 21.197 and 21.199 to operate airplanes to a base for the accomplishment of the inspections required by this AD.

Amendment 39-3575 became effective October 1, 1979.

This Amendment 39-3604 becomes effective November 1, 1979.

## Affected data sheets (1) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS A22WE](https://openairdocs.org/tcds/A22WE): The Boeing Company; names 3 of 11 models: DC-10-40, DC-10-10F, DC-10-10

## 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: 6 (6 by airframe model, 0 by engine model)
- Makers: Douglas 6

Models with the most aircraft:

- [Douglas DC-10-40](https://openairdocs.org/model/douglas-dc-10-40): 6 aircraft (airframe model)

All 1 models: https://openairdocs.org/ad/79-20-01/models.md
Every aircraft: https://openairdocs.org/ad/79-20-01/aircraft.md

Its text cites no advisory circulars or STCs.

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