# AD 78-20-03: Fire Suppression System

- Type: Airworthiness directive
- Status: Current
- Products: MD Helicopters 369D and 369H
- Effective: November 7, 1979
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Rotorcraft
- Amendment: 39-3307
- Registered aircraft: 212 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/0771548A138348F386256E12004985DB.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/78-20-03

## The airworthiness directive

78-20-03 HUGHES: Amendment 39-3307 as amended by Amendment 39-3599. Applies to Hughes Model 369D and 369H helicopters which have either the C-500 aerial spray system, STC No. SH184NW or the Chadwick C-500 fire suppression kit, STC No. SH567NW installed.

To prevent hydraulic fluid from entering the engine after a seal failure of the Chadwick hydraulic motor, accomplish the following:

Within the next 100 hours time in service or 30 days, whichever comes first, after the effective date of this AD, install a drain line on the engine mounting flange, Chadwick P/N 500- 60405-1, in accordance with Chadwick Service Bulletin 500-78-02 dated September 1, 1978, or later FAA approved revisions, or in a manner approved by the Chief, Engineering and Manufacturing Branch, FAA Northwest Region.

To prevent possible fatigue cracking of the helicopter undercarriage, accomplish the following: Within the next 50 hours flying time or six months, whichever comes first, after the effectivedate of this amended AD, install a doubler, P/N 500-60487-1, and grommet, P/N AN931-7-11, in accordance with Chadwick Service Bulletin 500-79-01 dated September 27, 1979, or later FAA approved revisions, or in a manner approved by the Chief, Engineering and Manufacturing Branch, FAA Northwest Region.

The manufacturer'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 Chadwick Inc., 11969 SW Herman Road, Sherwood, Oregon 97140. These documents may also be examined at FAA Northwest Region, 9010 East Marginal Way South, Seattle, Washington 98108.

Amendment 39-3307 became effective November 2, 1978.

This Amendment 39-3599 becomes effective November 7, 1979.

## Affected data sheets (1) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS H3WE](https://openairdocs.org/tcds/H3WE): MD Helicopters LLC; names 2 of 12 models: 369D, 369H

## 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: 212 (212 by airframe model, 0 by engine model)
- Makers: Hughes Helicopters 207, Summa 4, Hughes 1

Models with the most aircraft:

- [Hughes Helicopters HUGHES 369D](https://openairdocs.org/model/hughes-helicopters-hughes-369d): 207 aircraft (airframe model)
- [Summa 369D](https://openairdocs.org/model/summa-369d): 4 aircraft (airframe model)
- [Hughes 369H](https://openairdocs.org/model/hughes-369h): 1 aircraft (airframe model)

All 3 models: https://openairdocs.org/ad/78-20-03/models.md
Every aircraft: https://openairdocs.org/ad/78-20-03/aircraft.md

## Related documents

- [STC SH184NW](https://openairdocs.org/stc/SH184NW): Installation of Chadwick C-500 aerial spray system. Tower Aerospace, Inc, Named in the applicability
- [STC SH567NW](https://openairdocs.org/stc/SH567NW): Installation of tanks, pumps, and spray nozzles. Tower Aerospace, Inc, Named in the applicability

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