Definition
A private individual appointed by the FAA under 14 CFR Part 183 to act on the agency's behalf in performing specific airworthiness functions, such as issuing airworthiness certificates and approving aircraft for return to service after major repairs or alterations.
Plain English
A private person the FAA has authorized to perform certain aircraft inspection and certification jobs on its behalf, so the FAA does not have to send its own staff out for every task.
Context Anchor
You may see this term when a light-sport aircraft, experimental aircraft, or newly built aircraft needs an airworthiness certificate before it can be operated.
Derivation
Designated' comes from Latin designare, meaning 'to mark out' or 'to appoint.' 'Airworthiness' simply means fit to fly. So a designated airworthiness representative is literally an appointed person who represents the FAA in deciding whether an aircraft is fit to fly.
Why Pilots Care
Speeds up certification so owners and builders can get the aircraft legal to fly without long waits for FAA inspectors.
Analogy
Like a licensed inspector who can sign off on your home construction instead of waiting for a city official to visit every time.
Intuition Check
Do not assume this means any experienced mechanic or instructor. A designated airworthiness representative has specific FAA authority, and only for the tasks the FAA has allowed that person to perform.
Example Sentence 1
After completing the build, the owner contacted a designated airworthiness representative to inspect the aircraft and issue its airworthiness certificate.
Example Sentence 2
After the weight and balance check, the designated airworthiness representative reviewed the records and issued the special airworthiness certificate.