Whether you were builder of the airplane or not (or who does the modification), has no effect on what need to do following a modification.
The first thing to do is be clear on what the operating limitations for
your airplane require. Some limitations allow the owner to put the airplane back in phase I (with a log entry) and fly for an hour or two, and then approve it for flight in phase II with another log entry. Other limitations require that the FSDO responsible for your area be contacted and allow them to specify what period of testing is required. If you have the type that allows you to do everything, then it would be easy to do and should allow you to avoid any issues in the future.
In FAR 21 (can't find the reference right now) says
A ?minor change? is one that has no appreciable effect on the weight, balance, structural strength,
reliability, operational characteristics, or other characteristics affecting the airworthiness of the product. All other changes are ?major changes?. I realize this is pertaining to certificated aircraft but it is the only definition in the regs so it is often used as a guide for experimental.
As for what constitutes a major change.....?
The problem is, it is somewhat subjective, but what makes it even worse is that often opinion works its way in. Ask 10 different FAA airworthiness guys and you are likely to get at least 7 different answers.
All of the airworthiness guys that I know, that really do know their stuff, refer to the FAR's definition of a major change in
FAR 43, appendix A ( it is referred to as a major
alteration, but is generally considered to be the same as major change).
The paraphrased definition (within the FAA anyway) of a major change is generally accepted to be anything that
could change the handling qualities, performance, or
reliability of an aircraft.
The third one is often overlooked.
When we make the first flight of a newly built RV and then continue through phase I flight testing, to a large extent we are mostly testing the reliability of the engine and all of the systems installations. If built close to plans, the performance and handling qualities of new RV's should not contain any surprises. The
reliability of some of the installations is where problems most often pop up (as is evidence from many threads right here in theses forums).
It is for this reason that I believe most FAA guys would judge your change as major and recommend a small amount of phase one testing. The primary reason is to protect the general public (no passengers, and flight primarily over sparsely populated areas) with a small amount of flight testing.
I would agree in this case. Many on this forum would (will) disagree, and that's ok. Regardless of what anyone's opinion is, the primary goal is to be safe, and make sure we have met our operating limitations so that the FAA can't (well' at least minimize the chance) give us any trouble. The best way to do that is evaluate any change against appendix A and then take appropriate action based on our operating limitations.
If you contact a FSDO (if required by your operating limitations) because you think a change you made would be classified as major (based on appendix A), and the person you talk to says it is not... go fly. I would recommend that you ask them to put that on paper so that you have it in the future if needed.
Inverted fuel/oil, Major change?
I just wish I could afford to live the way I do 
Linear Mode
