Which category is allowed to sign a release to service after overhaul?

The category that is allowed to sign a release to service after an overhaul is the Base Maintenance Certifying Engineer. This position is critical because Base Maintenance involves more extensive and complex repair operations compared to Line Maintenance. A Base Maintenance Certifying Engineer typically holds a higher level of certification and is equipped with the necessary technical expertise and authority to ensure that the aircraft meets all safety and regulatory standards following an overhaul.

This role involves a comprehensive understanding of aviation regulations, as well as the specific maintenance procedures that have been performed on the aircraft. The Engineer's responsibility includes verifying that all systems have been checked and deemed airworthy, thereby ensuring compliance with both manufacturer specifications and regulatory requirements.

On the other hand, the roles listed in other options, such as Line Maintenance Certifying Mechanic or Technician, typically deal with less complex repairs and daily checks rather than significant overhauls. While these individuals play vital roles in aircraft maintenance, they are not authorized to sign off on the release to service after an overhaul, which involves more stringent oversight and certification requirements.