What certification confirms that maintenance work complies with airworthiness standards?

The maintenance release is the certification that confirms that maintenance work has been conducted in compliance with airworthiness standards. This document is crucial as it indicates that all required maintenance tasks and inspections have been completed satisfactorily, and the aircraft is deemed airworthy and ready for return to service.

The maintenance release involves specific criteria and regulations that must be followed to ensure safety and compliance with aviation authority standards. It assures stakeholders—including operators, regulatory authorities, and maintenance personnel—that the maintenance performed meets all relevant standards and regulations.

The other options, while related to maintenance and regulatory processes within aviation, do not serve the same purpose as the maintenance release. A return to service may indicate that an aircraft is ready to operate, but does not explicitly confirm compliance with all airworthiness standards. A release order and approved release, while important documents in various contexts, do not carry the same authority or purpose in confirming compliance with the airworthiness standards for maintenance work as the maintenance release does. Therefore, the maintenance release is the appropriate certification that ensures adherence to the necessary regulations for safe aircraft operation.