Hi Jim,
So long as you follow the RV manual and the Rotax manual you should not have any warranty or other issues. It's usually when people fail to follow the MFG recommendations that they run into problems.
I would highly recommend taking a class, but if not just make sure you have the manuals on hand and have the engine registered so you will get all the new bulletins and if you run into any problems call a Rotax tech right up front. This can save you time and money. If you want you can call me anytime.
The FAA annual inspection month may not line up with the hours and that's normal. So start your logbook out every time like this.
"In accordance with the Van's RV12 and Rotax maintenance manuals this aircraft was inspected for its 100 hr. and Annual Condition Inspection."
Absolutely make sure you do the Rotax 25 hr. inspection because that is a mandatory inspection to keep the warranty and the engine must be registered. You can use the Line maint. manual check list to help document the 25 hr. along with the logbook. Depending on the hours you fly you may never line up both inspection times.
Always sign off both inspections at the same time. They are very close to identical. There are a few differences, but you can include all of them each time or note why one may not be due until a certain time. Signing both off at one time keeps from having to do separate inspections.
The FAA does not care how often you do an annual. You could do one every month, but after the last one it is good for 12 months. Rotax doesn't really care about the exact 100 hour time mark, but when you do that inspection it is due 100 hours later.
On my plane I fly more than 100 hrs. per year so I always get to the 100 hr. first so I do the 100 hr. and include the annual. This resets both times for a fresh cycle.
So do it like this.
If you fly more than 100 hrs. a year then you will reach that mark first so do the 100 hr. and then include/sign off the annual.
If you fly less than 100 hours a year (i.e. 75 hrs) then you will get to the annual first, but sign off the 100 hour too.
I have talked to both parties (the FAA and Rotax) and neither care.
Rotax and the FAA rely heavily on the lookbook and check list if you have them as proof that thing were done since they can't stand there and watch.
I always use a Rotax Line maint. inspection check list and a Van's RV12 check list. These both get signed off for everything inspected with notes in the margins or at the end of the page for small problems. These get handed to the customer. I always give the customer a Discrepancy list and always write a good logbook inspection label. A normal inspection label for me is typed in #9 size font and most annuals/100 hour inspections are a page long. Just write down what you looked at, what you found and what you did to correct it. keep these list in a 3 ring binder. Really good record keeping can get you an extra $5k-$10 in re-sale value. People with really cruddy records usually take a good hit in money.
If you have a major warranty claim Rotax will want a copy of your logbook.
If your annual logbook entries are 2-3 sentence long for the entire annual it can and has caused some issues about what was done or not done. The logbook label is everything and in a court of law too if ever needed.
Here are two good articles to read from the Rotax website. At least read the first one.
http://www.rotax-owner.com/rotax-blog/item/22-good-documentation-its-everything
http://www.rotax-owner.com/rotax-bl...-cost-you-$10k-and-the-sale-of-your-aircraft?