I have no problems with requiring that hangars be used for "primarily aeronautical purposes", which could be interpreted as 50% of the floor space being used for aeronautical storage. But a partially built aircraft is certainly aeronautical.
How many of us have a waiting list for hangar space at our local airports? You buy a kit, you get on the waiting list for a hangar -- suddenly a hangar becomes available and you have to rent it then or not at all. Your airplane isn't really close to flying yet, but you take the hangar anyway. If you are writing to the FAA, don't forget to mention this scenario.
Why is this ruling a good idea, in principle? Consider the airport hangar stuffed with motor homes and second (or third) cars. With a three-year waiting list for hangar space for people who actually want to put an airplane in there. I think having some bureaucratic teeth to evict the project cars, boats and RVs is not a bad idea. But of course I agree that an airplane kit is appropriate.
Myself? I share a hangar with a friend who has *two* disassembled aircraft (which have actually flown many hours, but not recently -- right now they are future restoration projects). I have two utility trailers in there, too. So for a long time it was non-active-aircraft storage. But we recently put in a working airplane and I keep hoping that my Lancair project will migrate there soon (yeah, I've said that for years ... let's not go there!) This use of a hangar is certainly appropriate IMHO -- more so than the project car, RV and boat storage facility that some hangars seem to be.
- Rob Wolf