On Dec 4, 3:36*pm, Pat Russell wrote:
The "Operating Limitations" will require an annual "Program Letter" to
be sent to the local FSDO/FAA and placed in your aircraft folder.

I have seen this. *I have also seen Operating Limitations that do not
specify that Program Letters be submitted.

I have looked for a FAR or AC that requires Program Letters (in
general) to be submitted for Experimental Aircraft. *So far I haven't
found any such regulation.

-Pat

Say what? Ever heard of Google?

14CFR §21.193 Experimental certificates: general.

An applicant for an experimental certificate must submit the following
information:

(a) A statement, in a form and manner prescribed by the Administrator
setting forth the purpose for which the aircraft is to be used.

....

Darryl