AC 23-27 Changes

[jimrice]

Received my Swift Museum Foundation newsletter today. In reading it, I saw the following.

"There is also exciting news from the FAA Advisory Circular 23-27 dated 5/18/09, titled: Parts and Material Substitution for Vintage Aircraft. Our Swift meets the vintage definition and this allows AC allows parts such as identical bearings and belts from NAPA or other sources to be used with just a logbook entry. The biggest change is that existing Form 337 field approvals on the Swift are now approved data, which means the FSDO will approve a like 337 field approval on the Swift if the existing 337 copy is attached as the approved data."

I was trying to read and reseach some and typically, the FAA website seems to be down.......always seems to be in the evenings making me wonder if they turn it off when they go home!!!

I assume Cubs also fall into the defined "vintage" definition so 337s don't have to date back to 1955 (or whatever the specific date is) to be considered approved data. Am I reading this correctly? If so, this is great news........(yeah it is a bit dated, but I'm playing catch-up on my reading lately.)

EDIT: I was finally able to get online and read. Here is a critical piece. You should look it up and read for yourself and not take my word or snip and posts here.

[size=10pt]c. This AC limits discussion to the following conditions as they relate to function1) You may use the substitute part/material on secondary structures. Examples of thesewould include fuselage formers and stringers (typically on steel tube fabric covered aircraft), sidewindows, material on fabric covered aircraft, and wheel bearings. These substitutions may be aminor repair or alteration, and as such can be documented by logbook entry. Also refer tosection 13 "DOCUMENTING SUBSTITUTION" of this AC.(2) You may substitute parts where a direct substitute for a part/material can be foundunder manufacturer part number, military specification, or other recognized standard, such as theSAE.(3) When a direct substitution is not available, you may establish the replacementpart/material as at least equal to the original part/material per standards such as militaryspecifications and SAE (for example, the substitution of 4130 steel for milder steel). In thesecases, substitutions should be consistent with information already available in maintenancedocuments (Civil Aeronautic Manual (CAM) 18, AC 43-13, etc.).(4) You may use previously approved (per STC or field approval) part/materialsubstitutions on like-type aircraft. If the part/material is installed with previously approved partsor material, PMA, technical standard order (TSO), NAS etc., and if it is completed in a similarmanner consistent with a previous field approval or STC, you may use those approvals as thebasis for approval on your aircraft. However, if you want to use a previous field approval orSTC as the basis for approval on your aircraft, you must have all the previous field approval orSTC data, including any instructions for continued airworthiness, or develop any missing datathrough support from an appropriately authorized DER or ACO approval and permission fromthe STC holder (14 CFR parts 21 and 91, §§ 21.120 and 91.403(d)).

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[JimC]

 

[J5man]