# AD 89-25-02: Engine Idle Circuitry

- Type: Airworthiness directive
- Status: Current
- Products: Boeing 737-300 Series and 737-400 Series
- Effective: December 11, 1989
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Large airplane
- Amendment: 39-6402
- Docket: 89-NM-225-AD
- Registered aircraft: 30 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/71807A9747AB1A2D8625695E00604061.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/89-25-02

## The airworthiness directive

89-25-02 BOEING: Amendment 39-6402. Docket No. 89-NM-225-AD.

Applicability: Model 737-300 and -400 series airplanes, identified in Boeing Alert Service Bulletins 737-77A1026, Revision 2, dated October 27, 1989, and 737-77A1025, dated October 12, 1989, certificated in any category.

Compliance: Required within 60 days after the effective date of this AD, unless previously accomplished.

To reduce the risk of engine flameout during inadvertent airplane immersion into thunderstorm activity, accomplish the following:

A. For Model 737-300 series airplanes: Modify the engine idle circuitry in accordance with Boeing Alert Service Bulletin 737-77A1026, Revision 2, dated October 27, 1989.

NOTE: This action is in addition to the actions required by AD 88-13-51 R1, Amendment 39-6088, for the Model 737-300 series airplanes.

B. For Model 737-400 series airplanes: Modify the engine idle circuitry in accordance with Boeing Alert Service Bulletin 737-77A1025, dated October 12, 1989.

C. An alternate means of compliance or adjustment of the compliance time, which provides an acceptable level of safety, may be used when approved by the Manager, Seattle Aircraft Certification Office, FAA, Northwest Mountain Region.

NOTE: The request should be forwarded through an FAA Principal Maintenance Inspector (PMI), who will either concur or comment, and then send it to the Manager, Seattle Aircraft Certification Office.

D. 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 Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124. This information may be examined at the FAA, Northwest Mountain Region, Transport Airplane Directorate, 17900 Pacific Highway South, Seattle, Washington, or Seattle Aircraft Certification Office, 9010 East Marginal Way South, Seattle, Washington.

This amendment (39-6402, AD 89-25-02) becomes effective on December 11, 1989.

## Affected data sheets (1) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS A16WE](https://openairdocs.org/tcds/A16WE): The Boeing Company; names 2 of 17 models: 737-300 Series, 737-400 Series

## 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: 30 (30 by airframe model, 0 by engine model)
- Makers: Boeing 30

Models with the most aircraft:

- [Boeing 737-400](https://openairdocs.org/model/boeing-737-400): 8 aircraft (airframe model)
- [Boeing 737-436](https://openairdocs.org/model/boeing-737-436): 6 aircraft (airframe model)
- [Boeing 737-300](https://openairdocs.org/model/boeing-737-300): 4 aircraft (airframe model)
- [Boeing 737-490](https://openairdocs.org/model/boeing-737-490): 3 aircraft (airframe model)
- [Boeing 737-484](https://openairdocs.org/model/boeing-737-484): 3 aircraft (airframe model)
- [Boeing 737-301](https://openairdocs.org/model/boeing-737-301): 1 aircraft (airframe model)
- [Boeing 737-401](https://openairdocs.org/model/boeing-737-401): 1 aircraft (airframe model)
- [Boeing 737-306](https://openairdocs.org/model/boeing-737-306): 1 aircraft (airframe model)
- [Boeing 737-319](https://openairdocs.org/model/boeing-737-319): 1 aircraft (airframe model)
- [Boeing 737-330](https://openairdocs.org/model/boeing-737-330): 1 aircraft (airframe model)
- [Boeing 737-405](https://openairdocs.org/model/boeing-737-405): 1 aircraft (airframe model)

All 11 models: https://openairdocs.org/ad/89-25-02/models.md
Every aircraft: https://openairdocs.org/ad/89-25-02/aircraft.md

Its text cites no advisory circulars or STCs.

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