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Advisory Circular 20-147, Turbojet, Turboprop, and Turbofan Engine Induction System Icing and Ice Ingestion

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Federal Aviation Administration (FAA), DOT.


Notice of issuance of advisory circular.


This notice announces the issuance of advisory circular (AC) 20-147, Turbojet, Turboprop, and Turbofan Engine Induction System Icing and Ice Ingestion. This AC describes acceptable means, but not the only means, for demonstrating compliance with the applicable regulations, helping to reduce inconsistencies and eventual surprises to both engine manufacturers and engine installers, when installing a part 33 certified engine in a part 23 or 25 aircraft. This AC is intended for engine manufacturers, modifiers, foreign regulatory authorities, FAA engine type certification engineers and their designees. This AC is neither mandatory nor regulatory in nature and does not constitute a regulation.


The Manager, Aircraft Engineering Division, issued AC 20-147 on 2/02/04.

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John Fisher, Engine and Propeller Standards Staff, ANE-110, 12 New England Executive Park, Burlington, Massachusetts 01803; telephone: (781) 238-7149; fax: (781) 238-7199; e-mail: The subject AC is available on the Internet at the following address:​rgl.

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The FAA published a notice in the Federal Register on January 24, 2000 (65 FR 3752), and again on August 8, 2002 (67 FR 54011) to announce the availability of the proposed AC and invite interested parties to comment.

(Authority: 49 U.S.C. 106(g), 40113, 44701-44702, 44704.)

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Issued in Washington, DC, on February 2, 2004.

David W. Hempe,

Manager, Aircraft Engineering Division.

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[FR Doc. 04-2516 Filed 2-4-04; 8:45 am]