AC 20-27G covers building and maintaining a home built airplane. Advisory Circulars are not regulations and not mandatory, they are advisories only.
BUT if one attempts to build and certify a aircraft not in accordance with AC 20-27G, the FAA can and will deny certification.
As far as complying or not complying with a SB from Vans is concerned, that is up to the owner of the aircraft. But the owner needs be aware that operating the aircraft without complying could be construed as operating an unsafe aircraft and that is a violation of FAR's. Experimental aircraft are not exempt from the regulations with regard to safe flight condition.
This is all somewhat mirky but in the end one can not go wrong treating the SB as if it were an AD and making an entry in the log book that it has been complied with. No one concerned with the regulatory process be it the FAA, an insurance company or a future owner, will have a problem with such an action.
some definitions of terms need to be addressed in this type of thread.
first off, as stated, there is no such thing as a mandatory SB even in the standard certificate world.
an EAB is never airworthy. because it is not constructed under the rules of part 23, it cannot be described as airworthy. this is a issue I see a lot in logbooks, the word airworthy is not to be used in the signoff for a condition inspection. an EAB is only "found to be in a safe condition for flight" there is no definition of safe flight in anything the FAA puts out. that is up to the person that signs the logbook entry.
as for AC20-27G it has nothing to do with "found in a condition safe for flight" it states:
g. Meeting General Design and Construction Requirements.
(1) Amateur builders are free to develop their own designs or build from
existing designs. We do not approve those designs; it would be impractical to develop
design standards for the wide variety of design configurations created by designers, kit
manufacturers, and amateur builders.
it goes further when in following paragraphs it uses the phrase, " the designer should", notice it does not say "shall" big difference concerning what the FAA can do. as mel has stated many times, as the DAR its his call as to if the certificate is issued, there is really no hard guidance as to what is "safe for flight" a DAR must use their own experience to judge that, some are more conservative that others.
an insurance company would be hard pressed to deny a claim on an EAB that had a valid condition inspection. they might try to go after the person signing it, but even that could be a hard sell.
the point of all this is, there are really only a few things that must be in a logbook legally.
1. a condition inspection done in accordance with the operating limitations.
2. any AD that specifically calls out the aircraft,engine or appliance. most don't but some do. this one will be argued forever.
3.any inspection that is required by FARS such as transponder, pitot static ect
remember, the FAA is a government department that is really a legal firm. only the letter of the law is required.
so i agree with david that by complying and documenting it you can't go wrong, and its the correct thing to do, but there are a lot of things said in some of these types of threads that are just not legally true.
so inspect it, make a logbook entry such as "inspected rear horizontal spar in accordance with vans aircraft S/B 14-03-02 no cracks found. sign it and be done with it until the next c.
bob burns
RV-4 N82RB