Plus, who knows what "major damage" is.
The Army Air Force did, lol... In a nutshell: "Major damage" is that which, because of enemy action, weather, or accident, requires immediate repair/replacement of major components (ie:airframe, powerplants, avionics, life-support, or weapons delivery/defense sytems) that without which would render the aircraft NMC (Non -Mission Capapable) and/or not airworthy, and also to the extent that "any continued operation will pose a significant risk of further damage or total loss of aircraft or may pose risk of injury, illness,or loss of life to crewmembers" and minor damage as that caused by enemy action, weather, or accident which results in the aircraft still being airworthy, but only in a restricted/limited capability and requires repair/replacement of certain components or systems to ensure the aircraft is FMC(Fully Mission Capable).
Aircraft in the latter category may be "operated only in an emergency and/or in a limited capacity under certain restrictions outlined to and approved by the Squadron Maintenence Officer and approved by the Commander"...
What that basically means is an aircraft that's suffered minor damage can be flown if it absolutely HAS to be flown. The "certain restrictions" can mean a lot of different things and have to be listed specifically, like "may not be flown in combat areas", or "may only be ferried to nearest depot maintenence base for further repair with minumum crew necessary for safe operation", or "may not be flown above 10,000 feet " (like if the oxygen system was damaged)...
I was a member of the CAF's B-29 "FiFi" flight crew for two years and we used most of the same forms used by the USAAF "back in the day" (Naturally, along with all the regular required FAA stuff too) for her maintenance (No sense in re-inventing the wheel).
The aircraft's manuals contain copies of all the forms used by the USAF , including everything from the crew "squawk sheets" to all the major combat, damage, and accident reports. The only thing that hasn't really changed since 1945 is the paperwork (except that now there's more of it but a lot is now on "electronoic forms".
(Off-topic but good trivia): "FiFi" was built for the USAAF as a B-29A in 1944, delivered in 1945, then became a TB-29A, declared "Excess" (probably as a wing "hack", meaning some Colonel's private airplane), then returned to the USAF as a B-29A in 1951. She was then assigned to various SAC units, including being converted back to a TB-29A, until she was delivered to the Navy in 1957 and finally struck from the USAF rolls to be a missile target at China Lake Naval Weapons Training Range until we discovered and recovered her in 1971...
Sorry about the long-winded answer, but I'm waiting for the gloss black paint to dry on my CAF P-82 and got nothing else to do right now, lol...
As for you diorama plan, it sounds like you got a good handle on what you're gonna do with her, and I'm looking forward to seeing your work... I love B-17 dioramas and (aside from the fact that everything I build is for a diorama) think that there's no better way to display those wonderful birds..