Skip to Content


Advisory Circular; Turbine Engine Power-Loss and Instability in Extreme Conditions of Rain and Hail

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.

Start Preamble Start Printed Page 7904


Federal Aviation Administration, DOT.


Notice of issuance Advisory Circular (AC) on turbine engine power-loss and instability in extreme conditions of rain and hail.


This notice announces the issuance of Advisory Circular (AC), No. 33.78-1, Turbine Engine Power-Loss and Instability in Extreme Conditions of Rain and Hail. This AC may be used to demonstrate compliance with the requirements pertaining to § 33.78(a)(2) for turbine engines in extreme rain and hail. This AC is meant to provide information and guidance concerning an acceptable method, but not the only method, for compliance. While guidelines in this AC are not mandatory, they are derived from extensive Federal Aviation Administration (FAA) and industry experience in determining compliance with the requirements.


Advisory Circular No. 33.78-1, was issued by the New England Aircraft Certification Service, Engine and Propeller Directorate on February 8, 2000.

Start Further Info


John Fisher, Engine and Propeller Standards Staff, ANE-110, 12 New England Executive Park, Burlington, MA 01803, telephone (781) 238-7149, fax (781) 238-7199.

End Further Info End Preamble Start Supplemental Information



In 1988, the Aerospace Industries Association (AIA) initiated a study of airplane turbine engine power-loss and instability phenomena that were attributed to operating in inclement weather. AIA, working with the Association European des Constructeurs de Materiel Aerospatial (AECMA), concluded that potential flight safety threat exists for turbine engines installed on airplanes when operating in an extreme rain or hail environment. AIA and AECMA further concluded that the rain and hail ingestion requirements contained in § 33.77 did not adequately address these threats. Consequently, the Federal Aviation Administration (FAA) and the Joint Aviation Authorities (JAA) have promulgated additional rain and hail ingestion standards.

Interested parties were given the opportunity to review and comment on the draft AC during the proposal and development phases. Notice was published in the Federal Register on September 5, 1996 (61 FR 46893), to announce the availability of, and comment to the draft AC.

This advisory circular, published under the authority granted to the Administrator by 49 U.S.C. 106(g), 4113, 44701-44702, 44704, provides guidance for these new requirements that were published in the Federal Register on March 26, 1998 (63 FR 14794).

Start Signature

Issued in Burlington, Massachusetts, on February 8, 2000.

Thomas A. Boudreau,

Acting Manager, Engine and Propeller Directorate, Aircraft Certification Service.

End Signature End Supplemental Information

[FR Doc. 00-3702 Filed 2-15-00; 8:45 am]