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United States Department of Transportation United States Department of Transportation

AC 23-27 - Parts and Materials Substitution for Vintage Aircraft

Document Information

Parts and Materials Substitution for Vintage Aircraft
Date issued
Office of Primary Responsibility
ACE-100, Small Airplane Directorate

This advisory circular (AC) provides guidance for substantiating parts or materials substitutions to maintain the safety of old or out-of-production general aviation (GA) aircraft, or other GA aircraft where the parts or materials are either difficult or impossible to obtain. This AC also provides guidance about the data required to gain Federal Aviation Administration (FAA) approval for making these substitutions. This AC does not include specific approvals for installations. It provides guidelines to follow when collecting information needed for an FAA approval. The material in this AC is neither mandatory nor regulatory in nature and does not constitute a regulation. You may follow an alternate FAA-approved method. However, if you use the means described in this AC, you must follow it in all respects. Mandatory words such as "must" apply only to those who seek to show compliance to a specific rule by use of a method prescribed in this AC without deviation.