When must FAA reply to my letter? I have sent letters requesting action and/or clarifications to the FAA medical certifications branch.  How long can FAA legally delay before they are required to answer my questions in writing?
The FAA publication "MEDICAL FACTS FOR PILOTS" Publication #OK-06-002 states the time periods shown below. I don't know of any rule that mandates a response in any specific time period.

We will respond to your request for duplicate medical certificates within 3 working days of receipt.

We will respond to your request for full review of medical records within 30 working days of receipt of all the necessary records and testing.