Flydog,
I don't know where you got your degree, but perhaps you ought to get your money back. An engineering degree doesn't make you an aircraft mechanic, which is a dedicated study unto itself (mechanics and engineers dont' generally get along, but you already know that).
I'm surprised that they made you take an entire two years of dedicated study on aerodynamics while getting your engineering degree. That must be some degree.
The Forest Products Laboratory doesn't need to approve a glue, nor evaluate a glue, for it to be used on an aircraft structure. That has nothing to do with FAA approval. Being quite the airplane mechanic and wood expert, of course you know that it's up to the mechanic performing the work to certify that the wood is acceptable and meets FAA guidelines, and those of the aircraft manufacturer. You of course also know that woodwork on aircraft is very much an art, and only partially science.
In fact, you'll find that 43.13 in chapter 1 makes the following statement regarding the selection of wood and products to be used with wood: "Quality of Wood. All wood and plywood used in the repair of aircraft structures should be of aircraft quality (reference Army Navy Commerce Department Bulletin ANC-19, Wood Aircraft Inspection and Fabrication). Table 1-1 lists some permissible variations in characteristics and properties of aircraft wood. However, selection and approval of woodstock for aircraft structural use are specialized skills and should be done by personnel who are thoroughly familiar with inspection criteria and methods."
As for the FAA's treatment of adhesives on wood certificated structures, the following (also from AC 43.13 1A-2B) applies:
1-4. ADHESIVES. Because of the critical role played by adhesives in aircraft structure, the mechanic must employ only those types of adhesives that meet all of the performance requirements necessary for use in certificated civil aircraft. Use each product strictly in accordance with the aircraft and adhesive manufacturer’s instructions.
a. Adhesives acceptable to the FAA can be identified in the following ways:
(1) Refer to the aircraft maintenance or repair manual for specific instructions on acceptable adhesive selection for use on that type aircraft.
(2) Adhesives meeting the requirements of a Military Specification (Mil Spec), Aerospace Material Specification (AMS), or Technical Standard Order (TSO) for wooden aircraft structures are satisfactory providing they are found to be compatible with existing structural materials in the aircraft and the fabrication methods to be used in the repair.
This is the first time that you've heard airplanes are lifted from below? Wow. Let me know where you are, and we can get you into a private pilot ground school in the near future, so that you don't get left out. Unbelievable.
As an example, an average light airplane experiences about 2 ounces of lift, or "suck," in your engineering parlance, per square inch to create lift. Lift isn't created by this, however. Lift produced by the wing is proportional to the mass of airflow deflected by the wing, and to the vector imparted to that air.
If suction atop a wing were the cause of lift, we could simply put little "suckers" on top of the wing to create reduced pressure, and off we'd go, sans airspeed. Perhaps little nozzles dispersing lower pressure warm air, or something wonderful. However, it doesn't work like that. Dynamic pressure from beneath the wing, separated by a slightly reduced pressure above the wing, accounts for lift, and is measured by the downwash created, in accordance with Mr. Newton and his third "law."
Lift is largely created by a differential in pressure between the upper and lower surfaces of a wing, to be sure. However, it's not suction that keeps it aloft; that's a ridiculous notion. Nor is a significant amount of "suction" available (even on thick airfoil sections or those with pronounced camber). In fact, no "suction" exists, but only a slight reduction of pressure below ambient. But then as an engineering, mechanic, wood, and maintenance expert, you know this...especially after two years of dedicated college level aerodynamics study, right?
At a given loading and airspeed, an increase in angle of attack will produce a bigger pressure differential between the upper and lower surfaces of an airfoil. However, that doesn't mean that the airplane is being sucked into the air, nor is there a greater tendency to pull the fabric from the wings of an airplane when AoA is increased. During an increase in AoA, the pressure reduction from ambient does change slightly above the wing. However, the dynamic pressure and exposed area of the wing on the underside creates a larger pressure differential, and a greater amount of downwash.
I have no desire to debate aerodynamics here; but rest assured that airplanes aren't sucked into the sky. It just doesn't happen. The closest that this could be said to occur would be helicopters, which don't fly, nor are they sucked, but rather beat the atmosphere into tragic and temporary submission.
I'm in the process of building an airplane right now that doesn't even call for rib stitching (though I'll do it, out of habit and religious conviction). It's glued on...dope or superseam (for the Ceconite sinners out there). That's it. Many aircraft are just so.
I'm guessing your not a mechanic; certainly not an airframe mechanic. I am, as well as an inspector and even a counselor for EAA. I also have limited prior experience as a rodeo clown, can ride a unicycle, and juggle most small objects with aplomb. I suppose throwing out credentials such as an engineering degree changes the facts...but not the fact that an engineering degree doesn't make you an airframe mechanic, nor expert, nor does it provide you the experience to work on airplanes. College just doesn't do that...some things need to be learned the old fashioned way, don't they?
If you're really going to shell out eighteen grand to recover a fabric airplane, I'm going to go out on a limb and submit that the wrong subjects were covered in school; they omitted the really important subjects like common sense, basic economics, and the ability to determine when you're being taken to the cleaners ("Lock, stock, and barrell, 101, I believe). That's purely supposition; my education came in the field and what I know of a classroom only occured when watching television programs; I am an uneducated person.
It's a good thing you're not a mechanic, because with the understanding and dogged advocacy you've pursued on inaccuracies would make your work a hazard. Before you quote 43.13 or any other common-use industry reference, go read it, then put in the effort and long study required to obtain your mechanic certification...then advise others on these subjects.
"If it was a lost art it wouldnt be the primary method discussed in AC 43-13. "
AC 43.13 1B-2A isn't regulatory, and it isn't "the" method to be used. It's common industry practices that are acceptable when no other method is used. The Seine knot, for example, is the knot to be used when rib stitching, if no other knot is given, or the type of knot is unknown (such as when restoring a vintage aircraft). This doesn't mean that rib stitching with the seine knot is the recomended method of attaching fabric; not so at all. Chapter 2, Section 1 also covers the use of screws, rivets, or single-wire metal clips to secure the fabric to the wing.
---Steve, for eight grand, I'll come get the airplane myself. Other than needing a little recover, how's the rest of it?