STC's for Commander

WHAT IS AN STC?
A supplemental type certificate (STC) is a certificate issued when an applicant has received FAA approval to modify an aircraft from its original design.  The STC, which incorporates by reference the related type certificate, approves not only the modification but how that modification affects the original design.  

YOU'VE FOUND ONE YOU WANT TO INSTALL ON YOUR AIRCRAFT. WHAT DO YOU DO NOW?
You must contact the STC holder to seek written permission.  The STC and its related information-- all drawings, data, specifications--are the property of the STC holder.   The FAA will not release this information without authorization from the owner.    

YOU TRIED. COULDN'T FIND THE STC HOLDER.
If the mail you sent was returned "undeliverable" and there is no phone listing for the holder, please contact the issuing FAA office.   STCs are approved and issued through FAA aircraft certification offices (ACOs) which serve the geographic area of the STC owner's residence.   

YOU'RE INTERESTED IN GETTING YOUR OWN STC.
For information regarding the STC application process, you may contact the ACO in your geographic area.  You may also find it helpful to review related orders and advisory circulars, in particular, Order 8110.4B, "Type Certification Process," and AC 21-40, "Application Guide for Obtaining a Supplemental Type Certificate".

HOW DO YOU FIND WHAT STCs HAVE BEEN FILED THROUGH 337's IN YOUR AIRCRAFT FILE?
All 337's are mailed to FAA's Aircraft Registration's branch and filed in individual folders by registration number.  You may visit FAA aircraft registry's website at http://registry.faa.gov or contact them at:

WHAT'S ON THE STC LISTING PROVIDED HERE?
Each STC record will contain the STC number, the manufacturer, the model numbers, the type certificate number, a description of the modification, the applicable aircraft certification office, the STC holder with address, and date.