Who is responsible for restricting aircraft from flight until missing tools or parts are found?

The Maintenance Officer is responsible for ensuring the safety and airworthiness of the aircraft during maintenance operations, which includes a critical role in tool and parts accountability. When tools or parts are reported missing, it is the Maintenance Officer's responsibility to assess the situation and restrict the aircraft from flight until those items are located. This is done to prevent any potential safety hazards that could arise from tools or parts remaining inside the aircraft or being lost in an operational environment.

The other roles, while they play important parts in overall aircraft maintenance and management, do not carry the same direct authority regarding flight restrictions due to missing tools or parts. Quality Assurance Officers focus on maintaining standards and conducting inspections, Flight Crew Chiefs manage daily operations of flight crews, and Tool Control Officers primarily oversee the tracking and inventory of tools. However, the ultimate decision on whether an aircraft can remain in service is in the hands of the Maintenance Officer, who has the expertise and authority to take necessary actions for safety.