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Advisory Circular (AC) 20-73A “Aircraft Ice Protection”

Document Details

Information about this document as published in the Federal Register.

Published Document

This document has been published in the Federal Register. Use the PDF linked in the document sidebar for the official electronic format.

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Federal Aviation Administration (DOT).


Notice of availability and request for public comment.


This notice announces the availability of and requests comments on a draft Advisory Circular (AC) 20-73A, Aircraft Ice Protection. The draft AC provides general information related to the approval of aircraft ice protection provisions in accordance with Title 14 of the Code of Federal Regulations (14 CFR) parts 23, 25, 29, and 33. This draft AC also provides guidance and general information relative to operation of aircraft in icing environments that may affect the aircraft's airworthiness.


Sumbit comments on or before May 10, 2003.


Send all comments on the proposed draft AC to: Federal Aviation Administration, Aircraft Certification Service, Room 815, AIR-130, 800 Independence Avenue, SW., Washington, DC 20591. You may deliver comments to: Federal Aviation Administration, 800 Independence Avenue, SW., Room 815, Washington, DC 20591.

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Mr. George T. Soteropoulos, Federal Aviation Administration, Aircraft Certification Service, Room 815, AIR-120, 800 Independence Avenue, SW., Washington, DC 20591, Telephone: (202) 267-97960, FAX: (202) 267-5340.

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Comments Invited

You are invited to comment on the draft AC listed in this notice by submitting written data, views, or arguments, to the address listed above. Your comments should identify “Commments to AC 20-73A.” You can examine all comments on the draft AC before and after the closing date, at the Federal Aviation Administration, Room 815, 800 Independence Avenue, SW., Washington, DC 20591, weekdays except Federal Holidays between 8:30 a.m. and 4:30 p.m. The Director of the Aircraft Certification Service considers all communications received on or before the closing date before issuing the final AC.


Since its release on April 21, 1971, AC 20-73 continues to be followed as a means of compliance for inflight icing regulations. The objective of this revision is to provide a uniform and modern means of compliance with regulations for aircraft and engine ice protection requirements. This revision of AC 20-73 is extensive. It addresses common ice protection means of compliance for airplanes, rotorcrafts, and engines, with references to other applicable advisory circulars that address specific types of aircraft, engines, or regulations. An effort has been made in this revision to make the information congruent with compliance means provided in other existing guidance material and policies. Note however that there are instances where current technology is considered sufficient to justify changes, and means of compliance not previously addressed in guidance and policy material are discussed in this proposed document.

How To Obtain Copies

You may get a copy of the draft AC from the Internet at:​rgl. You may also request a copy from Mr. George T. Soteropoulos.

See the section entitled For Further Information Contact for the complete address.

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Issued in Washington, DC, on March 7, 2003.

Susan J. M. Cabler,

Deputy Manager, Aircraft Engineering Division, Aircraft Certification Service.

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[FR Doc. 03-6336 Filed 3-14-03; 8:45 am]