Brodhead Pietenpol Association

Original Posted By: Dmott9(at)aol.com
In a recent post of mine I stated that weldwood glue was FAA approved.One of the listers, in a mild rebuke, stated that it was not FAAapproved.Below is an EAA tech response to my question concerning FAA approvedglues. At the time I was building, 1982 - 1986, it was approvedMike B Piet N687MB (Mr Sam )+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++Mike,As the FAA guidance is currently written, the only adhesive that'sdefinitely approved for type certificated (TC) aircraft is Recorcinol. Older versions of FAA Advisory Circular AC 43.13 also indicated thatWeldwood was an approved adhesive, but the current version of the AC(43.13-1B) appears to indicate that Weldwood is not acceptable. However, there is some vagueness in the wording of the AC, and some IAsand FAA inspectors continue to approve Weldwood.For experimental aircraft, you are not required to use FAA approvedadhesives, so there would not be an issue with Weldwood.________________________________________________________________________________

Original Posted By: Michael Brusilow
The new "improved" 43.13 sucks. It leaves out lots of things simply becausethe FAA thinks no one knows how to use the methods anymore, the FAAcertainly doesn't. Plastic resin glue has always been, and still is,approved whether the FAA person who wrote the new 43.13 knows it or not.----- Original Message -----

Original Posted By: Isablcorky(at)aol.com
Michael Brusilow quoted an EAA tech as saying:> As the FAA guidance is currently written, the only adhesive that's> definitely approved for type certificated (TC) aircraft is Recorcinol. ...> However, there is some vagueness in the wording of the AC, and some IAs> and FAA inspectors continue to approve Weldwood.I read that section pretty carefully a while ago. The key sectionpasses the buck to other authorities, then qualifies it so much thatit hardly means anything. Here is the exact wording:"(2) Adhesives meeting the requirementsof a Military Specification (Mil Spec), AerospaceMaterial Specification (AMS), or TechnicalStandard Order (TSO) for wooden aircraftstructures are satisfactory providing theyare found to be compatible with existingstructural materials in the aircraft and the fabricationmethods to be used in the repair."Aside from that, resorcinols are specifically approved,assuming you are a good enough woodworker to makea close-fitting joint; urea-formaldehyde glues are singledout as being obsolete; and epoxies are termed acceptable"providing they meet the requirements of paragraph 1-4a,"which distills down to the section quoted above. Theonly other glue specifically mentioned is phenol-formaldehyde,which is cited as being used in aircraft plywood and is saidnot to be practical for use in structural repair.All this appears to mean that you are on solid ground onlyif you use resorcinol. Mil spec or one of the other standardsgives you some cover, but that business about "providingthey are found to be compatible" means "it's approveduntil you use it and one of our yo-yos says it's not." Orso it seems to me.Owen Davies________________________________________________________________________________