# AD 90-21-20: Relay box wiring & angle of attack sensors

- Type: Airworthiness directive
- Status: Current
- Products: Airbus A320-111, A320-211 and A320-231
- Effective: November 19, 1990
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Large airplane
- Amendment: 39-6770
- Docket: 90-NM-91-AD
- Registered aircraft: 14 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/18078AEBCA3C99BB8625695A00707B1A.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/90-21-20

## The airworthiness directive

90-21-20 AIRBUS INDUSTRIE: Amendment 39-6770. Docket No. 90-NM-91-AD.

Applicability: All Model A320-111, A320-211, and A320-231 series airplanes, certificated in any category.

Compliance: Required within the next 350 hours time-in-service after the effective date of this AD, unless previously accomplished.

To prevent the simultaneous activation in flight of two angle of attack sensors and subsequent incorrect pitch-down command to the elevator, accomplish the following:

A. Perform one of the following: 1. Disconnect and modify the wiring in the relay box 103VU, in Zone 127, and in Zone 232, in accordance with Airbus Industrie Service Bulletin A320-34-1012, Revision 1, dated April 10, 1990; or Revision 2, dated June 8, 1990; or 2. Accomplish Modification No. 21824P1953, which consists of moving the test control wires of the angle of attack sensors, in accordance with Airbus Industrie Service Bulletin A320-34-1013, dated June 1, 1990.

B. 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, Standardization Branch, ANM-113, FAA, Transport Airplane Directorate.

NOTE: The request should be submitted directly to the Manager, Standardization Branch, ANM-113, and a copy sent to the cognizant FAA Principal Inspector (PI). The PI will then forward comments or concurrence to the Manager, Standardization Branch, ANM-113.

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 documents from the manufacturer may obtain copies upon request to Airbus Industrie, Airbus Support Division, Avenue Didier Daurat, 31700 Blagnac, France. These documents may be examined at the FAA, Northwest Mountain Region, Transport Airplane Directorate, 1601 Lind Avenue S.W., Renton, Washington.

This amendment (39-6770, AD 90-21-20) becomes effective November 19, 1990.

## Affected data sheets (1) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS A28NM](https://openairdocs.org/tcds/A28NM): Airbus SAS; names 3 of 50 models: A320-111, A320-211, A320-231

## 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: 14 (14 by airframe model, 0 by engine model)
- Makers: Airbus Industrie 9, Airbus 5

Models with the most aircraft:

- [Airbus Industrie A320-211](https://openairdocs.org/model/airbus-industrie-a320-211): 6 aircraft (airframe model)
- [Airbus A320-211](https://openairdocs.org/model/airbus-a320-211): 3 aircraft (airframe model)
- [Airbus Industrie A320-231](https://openairdocs.org/model/airbus-industrie-a320-231): 2 aircraft (airframe model)
- [Airbus A320-231](https://openairdocs.org/model/airbus-a320-231): 2 aircraft (airframe model)
- [Airbus Industrie A320-111](https://openairdocs.org/model/airbus-industrie-a320-111): 1 aircraft (airframe model)

All 5 models: https://openairdocs.org/ad/90-21-20/models.md
Every aircraft: https://openairdocs.org/ad/90-21-20/aircraft.md

Its text cites no advisory circulars or STCs.

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