What must a mechanic do following a 100-hour inspection before returning the aircraft to service?

After completing a 100-hour inspection, it is essential for a mechanic to make proper entries in the aircraft's maintenance record before returning the aircraft to service. This requirement is crucial for maintaining an accurate history of the aircraft’s maintenance, ensuring compliance with regulatory standards, and providing valuable information for future maintenance and inspections. The entries must detail the work performed, any discrepancies found and corrected, and affirm the airworthiness of the aircraft post-inspection. This documentation serves as a legal record that can be verified by the Federal Aviation Administration (FAA) or other regulatory bodies.

While performing other tasks, such as changing the oil, conducting a test flight, or performing a fuel system check can be part of routine maintenance or specific needs of the aircraft, they are not mandatory steps following a 100-hour inspection itself. The documentation in the maintenance record is the critical component required to ensure the aircraft is properly logged and the maintenance protocol has been followed, making it a top priority.