# AC 20-134: Test Procedures for Maximum Allowable Airspeed Indicators

- Type: Advisory circular (guidance, not mandatory unless a rule or AD requires it)
- Status: Historical
- Approved: February 14, 1990
- Last reviewed: March 22, 2017
- Family: AC 20-134
- Cancels: AC 37-2A
- 14 CFR parts: 1
- Pages: 2
- PDF: https://openairdocs.org/files/sha256/4e/75/4e7559f1c697d70d9bf7a2139ce202643e06b4da0eb7b360f6b6348ad13189ef
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/7E0E80B8D4B1FE8D862569B50076929C.0001
- DRS record last changed: November 22, 2025
- Page: https://openairdocs.org/ac/20-134

## Versions

- [AC 20-134](https://openairdocs.org/ac/20-134) (Historical), approved Feb 14, 1990, 2 pages

## Text

Each page's text from the PDF; open the PDF at a page with #page=N. This is OCR from the scanned FAA advisory circular. OCR can misread letters and numbers.

### Page 1 (OCR)

Advisory of Transportation U.S. Department Circular Federal Aviation Administration Subject: Date: 2/14/90 AC No: 20-134 Initiated by: AIR-120 Change:

**TEST PROCEDURES FOR MAXIMUM**

**ALLOWABLE AIRSPEED INDICATORS**

1. PURPOSE. This advisory circular provides guidance concerning test procedures which may be used in showing compliance with the standards in Technical Standard Order C46a.

2. REFERENCE. Technical Standard Order (ISO) C46a, Maximum Allowable Airspeed Indicator Systems.

CANCELLATION. Advisory Circular 37-2A, Test Procedures for Maximum Allowable Airspeed Indicators, dated 10/22/74, is cancelled.

**4. TEST PROCEDURES.**

a. Test procedures set forth in the Society of Automotive Engineers (SAR) Aeronautical Standard (AS) 418A dated May 15, 1961, "Maximum Allowable Airspeed Instrument, Reciprocating Engine Powered Aircraft," or SAE AS 437 dated April 15, 1963, Maximum Allowable Airspeed Instrument, Turbine Powered Subsonic Aircraft, may be used for the purpose of showing compliance with related standards in TSO-C46a. However, environmental limits, or other limits, specified in these procedures must be adjusted if necessary to agree with those specified in TSO-C46a. Both aeronautical standards may be obtained from the Society of Automotive Engineers, 400 Commonwealth Drive, Warrendale, Pennsylvania 15096.

b. Other test procedures may also be adequate and valid for the purpose.

Willi Pullin William J. Sullivan Assistant Director, Aircraft Certification Service

### Page 2 (OCR)

U.S. Department of Transportation POSTAGE & FEES PAID BULK MAIL Federal Aviation FEDERAL AVIATION Administration ADMINISTRATION PERMIT NO. G-44 800 Independence Ave., S.W.

Washington, D.C. 20591

**FORWARDING AND RETURN**

POSTAGE GUARANTEED Official Business Penalty for Private Use $300

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