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Proposed Advisory Circular; Continued Airworthiness Assessments of Powerplant and Auxiliary Power Unit Installations on Transport Category Airplanes

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Federal Aviation Administration, DOT.


Notice of availability of proposed advisory circular and request for comments.


This notice announces the availability of proposed Advisory Circular (AC) No. 39.XX, Continued Airworthiness Assessments of Power plant and Auxiliary Power Unit Installations on Transport Category Airplanes.


Comments must be received on or before November 1, 2002.


Send all comments on the proposed AC to the Federal Aviation Administration, Attn: Engine and Propeller Standards Staff, ANE-110, Engine and Propeller Directorate, Aircraft Certification Service, 12 New England Executive Park, Burlington, MA, 01803-5299.

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Ann Azevedo, Engine and Propeller Standards Staff, ANE-110, at the above address, telephone (781) 238-7117, fax (781) 238-7199. A copy of the subject AC may also be obtained electronically by writing to the following Internet address:

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Comments Invited

A copy of the subject AC may be obtained by contacting the person named under FOR FURTHER INFORMATION CONTACT or by downloading the proposed AC from the following Internet website:​rgl. The FAA invites interested parties to comment on the proposed AC. Comments should identify the subject of the AC and be submitted to the individual identified under FOR FURTHER INFORMATION CONTACT. The FAA will consider all communications received by the closing date before issuing the final AC.


The proposed Advisory Circular (AC) describes the Continued Airworthiness Assessment Methodologies (CAAM). The Federal Aviation Administration (FAA) Engine and Propeller Directorate (EPD) and the Transport Airplane Directorate (TAD) may use CAAM to identify unsafe conditions and Start Printed Page 61948determine when an “unsafe condition is likely to exist or develop in other products of the same type design” before prescribing corrective action in accordance with Title 14 of the Code of Federal Regulations (14 CFR) part 39. CAAM is used for products associated with the Powerplant or Auxiliary Power Unit (APU) Installations on Transport Category Airplanes.

Continued airworthiness requires that safety concerns within the existing fleet be addressed, and the knowledge gained applied for the benefit of future fleets as well. This proposed AC also provides CAAM guidance for estimating the risks associated with identified unsafe conditions; defining prioritizing, and selecting suitable corrective actions for all identified unsafe conditions; and verifying that the corrective actions were effective. This proposed AC is intended to present a tangible means of logically assessing and responding to the safety risks posed by unsafe conditions.

This proposed AC does not establish any requirement that the FAA must perform a risk assessment before issuing an AD, or that the FAA must wait to issue an AD until the design approval holder performs a risk assessment, or that the FAA must accept the findings of a risk assessment performed by the design approval holder. CAAM, as described in this proposed AC, assists the FAA in making decisions concerning the priority in which unsafe conditions should be addressed. The FAA may issue an AD for a particular unsafe condition before a risk assessment is performed, or without having an assessment performed at all.

In this regard, CAAM does not define “unsafe condition” in a powerplant or APU installation. Rather, CAAM is a tool that the FAA usually will sue to make the kinds of decisions described above.

Note that the descriptive level of the CAAM process contained in this AC is aimed at the individual, whether from the FAA or the manufacturer, who is without extensive risk analysis experience. Some of the material within this AC will therefore seem very basic to the experienced analyst. Additionally, this proposed AC recognizes that an analysis must sometimes be performed without the benefit of readily-available information from the manufacturer. Typically, it is expected that more specific information will be available to the analyst, thus eliminating the need for some of the process steps that are described.

While information may be provided by and the assessment performed by the applicant, decisions as to whether an unsafe condition exists, and the appropriate responses to that unsafe condition, are exclusively the responsibility of the Administrator.

This proposed advisory circular, published under the authority granted to the Administrator by 49 U.S.C. 106(g), 40113, 44701-44702, 44704, provides guidance for the use of CAAM.

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Dated: Issued in Burlington, Massachusetts, on September 24, 2002.

Francis Favara,

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

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[FR Doc. 02-25053 Filed 10-1-02; 8:45 am]

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