# AD 88-03-09: Digital Flight Guidance Computer

- Type: Airworthiness directive
- Status: Current
- Products: Boeing DC-9-81 (MD-81), DC-9-82 (MD-82) and DC-9-83 (MD-83)
- Effective: March 11, 1988
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Large airplane
- Amendment: 39-5839
- Registered aircraft: 72 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/4AD1DDA87792EB84862569F2006DA5AE.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/88-03-09

## The airworthiness directive

88-03-09 MCDONNELL DOUGLAS: Amendment 39-5839. Applies to McDonnell Douglas Model DC-9-81, -82, and -83 series airplanes, as listed in McDonnell Douglas Service Bulletin 34-177, dated April 28, 1987, certificated in any category. Compliance required as indicated, unless previously accomplished.

To prevent erroneous information from being transmitted to the Digital Flight Guidance Computer (DFGC) from the Digital Air Data computer (DADC) in the event of an electrical transient, accomplish the following:

A. Within 12 months after the effective date of this airworthiness directive (AD), inspect Honeywell P/N HG280D80 DADC in affected airplanes to determine if Modification 8 has been installed, in accordance with Part 2 of the Accomplishment Instructions of McDonnell Douglas Service Bulletin 34-177, dated April 28, 1987, or later revisions approved by the Manager, Los Angeles Aircraft Certification Office, FAA, Northwest Mountain Region.

1. If Modification 8 has been installed and identified, no further action is necessary.

2. If Modification 8 has been installed but not identified, identify the DADC in accordance with the service bulletin.

3. If Modification 8 has not been installed, modify and identify the DADC in accordance with the service bulletin.

B. Alternate means of compliance which provide an acceptable level of safety may be used when approved by the Manager, Los Angeles Aircraft Certification Office, FAA, Northwest Mountain Region.

C. Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate airplanes to a base in order to comply with the requirements of this AD.

All persons affected by this directive who have not already received the appropriate service information from the manufacturer may obtain copies upon request to McDonnell Douglas Corporation, 3855 Lakewood Boulevard, Long Beach, California 90846, Attention: Director of Publications, C1-L00 (54-60); or Honeywell, Incorporated, Commercial Aviation Division Technical Services, Mail Station MN23-6345, P.O. Box 889, Minneapolis, Minnesota 55440. These documents may be examined at the FAA, Northwest Mountain Region, 17900 Pacific Highway South, Seattle, Washington, or the Los Angeles Aircraft certification Office, 4344 Donald Douglas Drive, Long Beach, California.

This Amendment becomes effective March 11, 1988.

## 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 3 of 25 models: DC-9-81 (MD-81), DC-9-83 (MD-83), DC-9-82 (MD-82)

## 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: 72 (72 by airframe model, 0 by engine model)
- Makers: Mcdonnell Douglas 71, Douglas 1

Models with the most aircraft:

- [Mcdonnell Douglas DC-9-83(MD-83)](https://openairdocs.org/model/mcdonnell-douglas-dc-9-83-md-83): 49 aircraft (airframe model)
- [Mcdonnell Douglas DC-9-82(MD-82)](https://openairdocs.org/model/mcdonnell-douglas-dc-9-82-md-82): 22 aircraft (airframe model)
- [Douglas DC-9-83](https://openairdocs.org/model/douglas-dc-9-83): 1 aircraft (airframe model)

All 3 models: https://openairdocs.org/ad/88-03-09/models.md
Every aircraft: https://openairdocs.org/ad/88-03-09/aircraft.md

Its text cites no advisory circulars or STCs.

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