Maintenance, certification and release to service (Part 43/145)
What this domain tests
This domain covers the maintenance process from task planning to release: approved data, parts and materials, inspection, certification and release to service under Part 43 and Part 145. The exam tests who may certify, what must be recorded, and when an aircraft may return to service.
Core rules
- Maintenance must be performed using approved or acceptable data, and with parts and materials that are approved for the installation. Unapproved parts or undocumented components break the certification chain.
- Part 43 sets the general maintenance and return-to-service rules, including certification of maintenance and the records that must be made.
- Part 145 applies to approved maintenance organisations. The organisation works to its MOE, uses a work package, controls calibration and training, and issues a release to service through authorised certifying staff.
- A release to service is not a general statement that the aircraft is perfect. It certifies that the maintenance recorded has been completed in accordance with approved data and that the aircraft or component is airworthy in respect of that work.
- If work is incomplete, the aircraft must not be released as though it were complete; deferral is only permitted where the applicable rules and approved systems, such as an MEL, allow it.
Worked example
An AME replaces a landing gear component. The task card references the manufacturer's maintenance manual, the replacement part has an authorised release document, and the required retraction test is performed. The AME records the task, part traceability, data reference and test result, then certifies the maintenance. In a Part 145 organisation, the certifying staff signs the release to service for the work package; the aircraft may then be returned to service for that work. If the test had not been done, the release would be premature even if the component fitted correctly.
Traps
Do not equate 'work done' with 'released'. Do not sign for work you did not personally ensure was completed and inspected. Do not use a maintenance release to cover known defects that should be deferred under an MEL or repaired. Missing data references and part traceability are frequent record failures.