Which of the following is NOT an authorized action for a mechanic with a powerplant rating?

The correct choice highlights an important limit on the authority of a mechanic with a powerplant rating. While a mechanic with such a rating is qualified to perform various tasks related to engines and propellers, there are specific limitations to their scope of responsibilities, especially concerning approving the return of aircraft to service.

Mechanics with a powerplant rating are primarily trained to handle engine maintenance, adjustments, and propeller-related work. They can conduct pre-flight inspections related to the engine and perform necessary adjustments on the engine itself, ensuring that everything is functioning correctly before flight. However, the authority to approve an aircraft for return to service after major repairs typically lies with a higher level of certification, usually a certified repairman or an FAA-certificated mechanic with both airframe and powerplant ratings. This distinction emphasizes the importance of having comprehensive oversight for significant repairs, especially those that impact overall safety.

Thus, the role and responsibilities of the mechanic with a powerplant rating are more focused and do not extend to making judgment calls about major repairs and return-to-service authorizations, underscoring the importance of higher certifications for such critical responsibilities.