Creating a PMA part. Well next to buying a new OEM part this is the second most expensive method unless you plan on selling your parts as a replacement for the OEM part. Again FAA procedures need to be followed and are usually performed by an FAA DER. Some projects can be simple whereas others complex so the generation of the required engineering data is time consuming. Usually this is an estimated charge in hours to complete the project and a significant amount of time. Typically this takes from 6 months to one year to accomplish. You are also charged an up front fee and then progress payments with the final payment due at final document submittal prior to issue of the PMA. If you want to install overseas an Supplemental Type Certificate is required. These two options are usually the most expensive route to go since you have to have the proper facilities, documentation systems and coordinate among multiple FAA entities in order to produce FAA approved parts for sale.