Document Offers Guidance For Owners, Safety Inspectors

The FAA has issued an Advisory Circular (AC) dealing aircraft certified before January 1, 1980, and vintage aircraft maintenance issues. The document, dated May 18th, is not intended to be regulatory. It was developed in consultation with industry representatives including EAA and EAA’s Vintage Aircraft Association.

The AC is provides guidance for substantiating parts or materials substitutions to maintain the safety of old or out-of-production GA aircraft, or other GA aircraft where the parts or materials are either difficult or impossible to obtain. The document also provides guidance about the data required to gain FAA approval for making these substitutions.

It does not include specific approvals for installations, but it does provide guidelines to follow when collection information needed for FAA approval. Based on work done, the aviation safety inspector makes the final determination for any approvals. The guidelines in the AC promote consistency, and reduce the time required to accomplish safety-enhancing upgrades.  The FAA says it is a 'living document', and sections may be added to as additional data is gathered.

Since many vintage aircraft no longer have factory support for replacement parts, an approved or the data describing the original part may be difficult to find, or no longer exist.

The circular does define the roles of FAA ASI's and engineers. For instance, ASI's should not make material substitution decision for issues involving design function, loads, and stresses, material properties, chemical composition, heat treatments and similar items.

The FAA says the most important aspect to consider when substituting parts is whether the failure of the part would prevent continued safe flight and landing. Appropriately authorized Designated Engineering Representatives have the necessary knowledge, skill, experience, interest, and impartiality to have earned the responsibility for making these determinations, and findings of compliance with the applicable airworthiness regulations.

FMI: www.faa.gov