Airworthiness Code
 

Hi guys,
just wondering what is actually airworthiness code ?
I am a little bit confused when I googled airworthiness code
Airworthiness code is Part 21, Part 145, Part 147 ? or it was CS23, CS25/ FAA Part 21, Part 23, Part 25 ?

It always important to note what country or CAA you are under to get the most accurate answer. Here is the FAA version.

Airworthiness code: Technically the Code of Federal Regulations (CFR) are referred to as regulations or rules and not "codes." Part 23, 25, 27, 29, 31, 33, 35 are regulations that address Airworthiness Standards required to be met to receive an airworthiness approval. Part 21 lists the requirements for those airworthiness approvals, e.g., type certificate, etc. Part 145 and 147 in your example cover certification requirements for repair stations and maintenance schools and are a separate topic from the other Parts you listed. Here is a link the official eCFR listing covering aviation. Open the Chapter I menu for the listings you noted: https://www.ecfr.gov/current/title-14

MOR/SDR: There are various reporting requirements within the CFRs usually governed by the type of operation. For example, SDRs are required for most non Part-91 operations (121, 135) and certain maintenance operations (145). The specific MOR term doesn't ring a bell but if it is used within the FAA it could be for airports or other non-aircraft type operations.

TSO/PMA: These are Part 21 airworthiness approval processes. An STC is another similar one. In general, the main difference between them is a TSO authorization provides a vendor with a design approval to an established minimum standard and a production approval so they may develop, manufacture, sell a part for possible use on a certified aircraft. A TSO does not provide an aircraft installation approval which is left to the Part 43 installer to determine. Also there are only a limited number of part types covered by a TSO. A PMA also provides a design approval and production approval similar to a TSO but a PMA also provides specific aircraft installation approval. A PMA is not bound to any established minimum standard like a TSO and can use several different design methods in the approval process. A PMA is a more involved process which most vendors use for 3rd party aircraft replacement parts.