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Advisory Circular 23-XX-21, Airworthiness Compliance Checklists for Small Airplanes During Major Alterations

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Federal Aviation Administration (FAA), DOT.


Notice of availability of proposed advisory circular (AC) and request for comments.


This notice announces the availability of and requests comments on a proposed AC. Proposed AC 23-XX-21 provides guidance material for the creation and use of airworthiness compliance checklists for small airplanes that can be used when making major alterations to small airplanes. Use of these compliance checklists should be limited to alterations that have been determined to be “major” alterations, as defined in 14 CFR part 1, but which are not so complex that they require an STC, per FAA Order 8300.10, as amended. Material in this AC is neither mandatory nor regulatory in nature and does not constitute a regulation.


Comments must be received on or before July 27, 2004.


Send all comments on the proposed AC to: Federal Aviation Administration, Small Airplane Directorate, Aircraft Certification Service, Regulations and Policy (ACE-111), 901 Locust Street, Kansas City, Missouri 64106.

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Mr. Taylor Martin, Standards Office, Small Airplane Directorate, Aircraft Certification Service, Kansas City, Missouri 64106, telephone (816) 329-4138, fax (816) 329-4090.

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Any person may obtain a copy of this proposed AC by contacting the person named above under FOR FURTHER INFORMATION CONTACT. A copy of the AC will also be available on the Internet at​AC within a few days.

Comments invited: We invite interested parties to submit comments on the proposed AC. Commenters must identify AC 23-XX-21 and submit comments to the address specified above. The FAA will consider all communications received on or before the closing date for comments before issuing the final AC. The proposed AC and comments received may be inspected at the Standards Office (ACE-110), 901 Locust, Room 301, Kansas City, Missouri, between the hours of 8:30 a.m. and 4 p.m. weekdays, except Federal holidays by making an appointment in advance with the person listed under FOR FURTHER INFORMATION CONTACT.

Background: The data and documentation requirements for major alterations can vary considerably. This variation can be attributed to the following: Differing complexity of the alterations, different sources of data submitted, and uncertainty of what data is actually required to show compliance with the applicable regulation during the submission to the FAA. Standardization of particular airplane alterations data submission and process shall be assured through the use of compliance checklists. The FAA will establish a library of checklists that will be periodically updated. This will eliminate the need to generate individual data package requirements when a modifier has performed a modification on a similar aircraft. Each checklist identifies the pertinent regulation as the certification basis of the airplane for the alteration. It also lists the manner in which the data can be approved. Reducing the approval process time requires up front involvement between the FAA and the applicant in project planning, open and constructive communication, and safety-focused project management. Using a compliance checklist should result in a more effective use of FAA and industry resources by establishing standard data and documentation requirements. Accordingly, the FAA is proposing and requesting comments on AC 23-XX-21.

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Issued in Kansas City, Missouri on May 19, 2004.

James E. Jackson,

Acting Manager, Small Airplane Directorate, Aircraft Certification Service.

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[FR Doc. 04-12066 Filed 5-27-04; 8:45 am]