In a move intended to help keep antique/classic aircraft safely maintained, restored and flying, the FAA has issued a new Advisory Circular AC 23-27, Parts and Materials Substitution for Vintage Aircraft, effective as of May 18th, 2009. This AC, created by the FAA's Small Airplane Directorate in Kansas City, Missouri, was a joint effort by the FAA in consultation with industry and sport aviation interests, including the AAA.

The original impetus for this AC came in 2004 from the FAA's Small Airplane Directorate in Kansas City, MO. Mike Gallagher, then Manager of the Kansas City SAD office, encouraged the FAA Ad Hoc Committee on Aging Aircraft to follow up their successful collaboration on the "Best Practices Guide for Maintaining Aging General Aviation Aircraft" with an Advisory Circular providing for parts and material substitutions for antique/classic aircraft. This group was comprised of FAA representatives, including Marv Nuss, Barry Ballenger, Mark James and Vy Nguyen (among others), as well as representatives from manufacturers, various type clubs and organizations. The list of that group included representatives from Cessna, Raytheon, Twin Commander, Charlie Nelson from the Swift Association, Neal Pobantz from the American Bonanza Society, Earl Lawrence and H.G. Frautschy from the EAA, the AOPA, and Brent Taylor from the Antique Airplane Association. It was this group that originally drafted what is now the finished AC.

This Advisory Circular will help provide guidance to both owner/restorers and FAA aviation safety inspectors when collecting information needed for an FAA approval, when parts or materials used in the original construction of the type-certificated airplane are no longer available, or newer, more appropriate materials are now common and would be more appropriate to be used when repairing or replacing components.

This AC, an outgrowth of the FAA's recognition that obtaining exact original parts and materials was becoming problematic for aircraft restorers and owners, is an example where the agency has reached out for input to resolve a problem.

The advisory circular details the level of information needed to document a part or material substitution, and while it is not intended as a "how to" manual, it does give specific examples of the types of changes that can be made, some with a simple logbook entry.

As an example, clear guidance is given regarding the substitution of 4130 steel instead of older, milder steel specifications in both non-structural and structural applications. Of course, structural modifications or repairs are still considered major repairs requiring FAA approval, typically done via an FAA Form 337.

This AC will apply only to gliders, or fixed-wing aircraft powered by reciprocating engine(s) which are unpressurized and have a certificated weight of 12,500 pounds or less, and were certificated before January 1, 1980 (and follow-on type certificated models of the same aircraft) as well as those certificated under Group 2 Memos, (and ATC aircraft certificated by the Department of Commerce) are eligible for parts and material substitutions using AC 23-27 as approved data. Also, the change cannot cause a perceptible change to the certification basis for that particular airplane.

It is expected that this AC will be a living document, amended as new examples of parts and materials substitutions come to the attention of the FAA.

We suggest that you click this link to read, review and keep this AC in your technical library for reference and referral.

While a long time coming, this AC is a welcome, positive step in helping to keep our old airplanes flying.

Brent Taylor