On Monday, May 6, 2019 at 10:30:09 PM UTC-4, Charles Longley wrote:
So you’re saying that all experimental gliders need program letters? I didn’t see any mention of a program letter in the glider I am buying.

I don’t know the answer if any particular club is submitting a program letter. Whenever I do a condition inspection and notice one in the files I remind the owner to submit their yearly letter.

I don't recall exactly when the requirement for program letters was added to the operations limitations for Experimental exhibition and air racing category gliders, but it was more than 15 years ago.
When moving to a new operating area, sending a program letter to notify the cognizant FSDO of the change of base will normally suffice.
Some limitations may require issuance of new operating limitations. This is fairly rare has gone away in more recent times with standardization.
Older ships may have no such requirement. Don't lose those operating limitations because you will then have to get new ones to later standards.
Unless otherwise stated in the docs, duration is unlimited.
Change in N number triggers all new stuff when new airworthiness certificate is issued.
The key thing is to review the operating limitations that are part of the airworthiness certificate and comply.
It isn't all that hard but I still find ships that don't have correct paperwork.
UH