Who is authorized to grant zero time to a rebuilt aircraft engine?

The authority to grant zero time to a rebuilt aircraft engine lies primarily with the manufacturer. This is because the manufacturer has established the criteria and standards for what constitutes a complete rebuild and can provide documentation certifying that the engine has been restored to a condition equivalent to that of a new engine. Essentially, the manufacturer has the responsibility for ensuring that all components meet the required specifications and safety standards, allowing them to assign the zero-time status for that engine.

Other individuals, such as certified powerplant mechanics, A&Ps with inspection authorization, or any licensed aircraft technician, do not have the same level of regality or established criteria for assigning zero time. They can perform significant maintenance, repairs, and overhauls but ultimately rely on the manufacturer’s validation for issuing zero time. Thus, the obligation to grant zero time is specifically a manufacturer’s responsibility, reinforcing their role in the maintenance and airworthiness process.