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

In the context of aircraft maintenance and overhaul, the category that is permitted to sign a release to service is Category C. This category pertains to individuals who have received specific training and have the authority to carry out major repairs and alterations, which includes comprehensive overhaul work. A release to service is a formal document that certifies that the aircraft has undergone the necessary inspections and repairs and is deemed safe and airworthy for operation.

Category C personnel have the highest level of authority concerning maintenance and are qualified to ensure that all repairs and maintenance work meet the required safety standards, regulations, and manufacturer specifications. Their role is critical in maintaining the integrity of the aircraft post-overhaul, making their sign-off essential for the release.

In contrast, the other categories, such as CAT A, B1, and B2, have different scopes of work and qualifications. For example, Cat A generally deals with line maintenance and simple repairs, while B1 and B2 focus on specific aircraft systems (mechanical and avionics, respectively) but do not possess the same level of authority to sign off on comprehensive overhauls as Category C does. This distinction highlights why Category C is the correct answer to the question regarding who can sign a release to service following an overhaul.