# AD 89-23-03: Glide Slope Antenna

- Type: Airworthiness directive
- Status: Current
- Products: Embraer - Empresa Brasileira de Aeronautica EMB-120 and EMB-120RT
- Effective: November 27, 1989
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Large airplane
- Amendment: 39-6368
- Docket: 89-NM-86-AD
- Registered aircraft: 3 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/73B2B772F54358EA862569ED006A9B76.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/89-23-03

## The airworthiness directive

89-23-03 EMPRESA BRASILEIRA DE AERONAUTICA, S.A. (EMBRAER): Amendment 39-6368. Docket No. 89-NM-86-AD.

Applicability: Model EMB-120 series airplanes, as listed in EMBRAER Service Bulletin 120-034-0072, dated April 14, 1989, certificated in any category.

Compliance: Required within 100 days after the effective date of this AD, unless previously accomplished.

To prevent erratic glide slope information during IFR approaches, accomplish the following:

A. Replace the Chelton glide slope antenna, P/N 17-21F6P3, with a Collins glide slope antenna type 37P5, P/N 522-0700-023, and install a pedestal-type support P/N 120-47294- 001, in accordance with EMBRAER Service Bulletin 120-034-0072, dated April 14, 1989.

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, Northwest Mountain Region.

NOTE: The request should beforwarded through an FAA Principal Maintenance Inspector (PMI), who will either concur or comment and then send it 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 EMBRAER, 276 S.W. 34th Street, Fort Lauderdale, Florida 33315. These documents may be examined at the FAA, Northwest Mountain Region, Transport Airplane Directorate, 17900 Pacific Highway South, Seattle, Washington, or Atlanta Aircraft Certification Office, 1669 Phoenix Parkway, Suite 210C, Atlanta, Georgia.

This amendment (39-6368, AD 89-23-03) becomes effective on November 27, 1989.

## Affected data sheets (1) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS A31SO](https://openairdocs.org/tcds/A31SO): Embraer S.A.; names 2 of 5 models: EMB-120, EMB-120RT

## 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: 3 (3 by airframe model, 0 by engine model)
- Makers: Embraer 3

Models with the most aircraft:

- [Embraer EMB-120](https://openairdocs.org/model/embraer-emb-120): 3 aircraft (airframe model)

All 1 models: https://openairdocs.org/ad/89-23-03/models.md
Every aircraft: https://openairdocs.org/ad/89-23-03/aircraft.md

Its text cites no advisory circulars or STCs.

---
OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.