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FAA Issues New Advisory Circular
for Vintage Aircraft
The FAA has issued new Advisory Circular, AC 23-27, Parts and Materials Substitution for Vintage Aircraft, dat- ed May 18, 2009. The AC, created by the FAA’s Small
Airplane Directorate in Kansas City, Missouri, was a joint
effort by the FAA in consultation with industry representatives including EAA and EAA’s Vintage Aircraft Association.
The publication gives 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.
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
with a simple logbook entry. Examples shown in appendix
1 include the use of ANSI specifications for bearing substitutions, or the use of generator or alternator belts made to
an SAE specification.
In Appendix 2, clear guidance is also 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.
Only 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 which 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.
To review the AC, go to http://rgl.faa.gov/. Click on
the Advisory Circulars link on the right side of the page.
On the next page, type in 23-27 in the search window
and a link to the AC will appear.
If you have suggestions regarding the incorporation
of other parts and material substitutions, send them
to (please copy the Vintage Aircraft Association at
FAA Small Airplane Directorate
Attn: ACE-100/AC23-27 comments
Kansas City, MO 64106-2641