Drew,
If you would like a decent set of guidance material, email me on the side, and I'll zap you a copy.
14CFR Part 1 (FAR 1.1) defines Major and Minor, with respect to definition as associated with Alteration and Repair.
Your Operating Limitations speak to FAR 21.93 - although this Part is applicable, by regulation, to Type Certificated products, the application of the definition of Major & Minor from this Part applies to your homebuilt, per your Operating Limitations.
I short, here is a portion of the guidance material I noted in my opening - interestingly enough, this originated out the Portland FSDO a few years ago, and is titled, "Nortwest Mountain Region - Guide to Aircraft Alterations":
201. MAJOR VS. MINOR ALTERATIONS
a. The definition of major alteration in FAR 1 is: “Major Alteration” means an alteration not listed in the
aircraft, aircraft engine, or propeller specifications-
(1). That might appreciably affect weight, balance, structural strength, performance, powerplant operation, flight characteristics, or other qualities affecting airworthiness;
or
(2). That is not done according to accepted practices or cannot be done by elementary operations.
b. This definition is reasonably clear except the meaning of “appreciably” and the phrase “...or other qualities affecting airworthiness...”. In this regard, major alteration is considered to include any alteration
which as a result of malfunction or improper accomplishment could:
(1). Preclude continued safe flight and landing in any type operation for which the aircraft is approved;
or
(2). Adversely affect the safety of crew or passengers.
c. A minor alteration is defined as any alteration other that major.
202. DISCUSSION
a. For practical purposes, alterations and changes to type design have the same definition. Part 43, appendix A, provides a listing of product alterations classified as major alterations. This list is not and cannot be all-inclusive. Anyone proposing to alter or approve an alteration to a type certificated product must make a judgement whether the alteration is major or minor. The definition in FAR 1 serves as the foundation to make this judgement. As noted in paragraph 201, the difficulty in applying these definitions is determining the meaning of “appreciable” and “other qualities affecting airworthiness”.
-snip-
c. “Appreciable effect” and other “qualities affecting airworthiness” must be considered for the proposed alteration. Webster’s 9th New Collegiate Dictionary definition of appreciable is “capable of being valued or estimated”. Thus any effect that could be valued or estimated would be appreciable. Appreciable is the value of such measurable effect.
-snip-
f. Performance. Aircraft performance is determined primarily by the difference in the aircraft’s available thrust and the aircraft’s aerodynamic drag in a given flight condition. Any alteration to the aircraft, aircraft engine, or propeller that may affect thrust, drag, or other changes that may affect the airflow over the aircraft, is likely to affect performance. If experience or accepted guidelines have demonstrated that the alteration (such as a small antenna installation) does not produce a measurable effect on performance, then the alteration is minor with regard to performance.
-snip-
h. Flight characteristics are similar to and closely related to aircraft performance. Thus, any alteration that may produce such an effect, such as a change in the length or width of flight controls or power, is a major alteration.
So, in providing my advice to Dave, I used the guidance from Paragraphs (f) and (h), above. In my experience, either paragraph could make me make a Major determination for the VG addition. The big key, for me, is in Paragraph (h): "Any measurable change to thrust or drag that affects performance is also likely to affect flight characteristics and requires engineering flight test for evaluation". Would you, upon putting VGs on your canard, do dedicated and well-documented engineering flight test(s)? I'd hope so, especially since your airplane is a one-off, not-duplicated-exactly-anywhere, non-Type Certificated air machine. Just because the VGs worked marvelously on 'ol what's-his-name's Long-EZ, does not absolutely guarantee they will work the same on 'ol what's-his-face's Long-EZ. The fact that you NEED to flight test, in order to determine what the airplane's new handling/performance characteristics are, would drive me to a Major determination. Again, Dave's FSDO deemed it a Minor, and again, if you done told the Feds everything, and they reach a conclusion, that'd be it for me...
So, wheelpants. Here's my take, from past personal experience.
When I flew my first VariEze, I opted out of installing the wheelpants. Figured I get to then "next winter". At Copperstate 1995, Gary Hertzler gently chided me on "dragging those draggy wheels all the way from Seattle to Phoenix". Having the Master admonish me like that, was a life-changing event... But I digress in my shame from 10 years ago...
Upon installing the pants, the FSDO said I was OK to proceed, without a new C of A, but that I should still flight test (which is what I planned to do anyway). Yee-haw! 8 knots more poop on account of the pants. Flight test also showed that I ran out of forward trim above 135 knots - the reduced pitch trim requirement of the airplane on account of the wheelpant installation required collateral changes in the pitch trim springs. Did the wheelpants have an appreciable effect? Yes - Higher cruise speed, and requirement to re-rig the pitch trim system. A seemingly innocuous change, that I would still classify as a Major change.
I have to deal, literally, with Major/Minor determinations every day at work. They are not all black/white cut or dry. Some are, but some are more insidious. In the homebuilt realm, I prefer the cautious/conservative route, primarily (again) because we are not dealing with airplanes of established Type Design with associated Type Certification.
Enuf, sez I. I have an Eze in the garage awaiting more meddling.
Hope this adds benefit, and was not too long and hideous to read.
Nitey-night,
-Joe Person
EAA Tech Counselor 4418
VariEze N79JN
Bothell, WA (KPAE)
