What certificate and ratings are required for a mechanic to conduct a 100-hour inspection and approve the aircraft for return of service?

• A. A mechanic certificate with an Inspection Authorization.
• B. A mechanic certificate with both airframe and powerplant ratings.
• C. A pilot certificate.
• D. A maintenance supervisor certificate.

Answer: (B)

The key idea is that a 100-hour inspection and the return-to-service sign-off must be performed by a certificated mechanic who has both airframe and powerplant ratings. That combination shows the technician is qualified to inspect and assess all major areas of the aircraft, including the structure and the propulsion system, and to determine airworthiness after the inspection. The 100-hour inspection does not require an Inspection Authorization—that falls under annual inspections and certain major work. A pilot certificate covers flight operation, not maintenance, and there isn't a separate “maintenance supervisor” certificate that would fulfill this maintenance-signing requirement.