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145.A.50 requires that a certificate of release to service (CRS) is issued by appropriately authorised certifying staff upon completion of any maintenance, confirming that the work has been carried out in accordance with the applicable requirements.
What it means in practice
No aircraft or component may be returned to service after maintenance until authorised certifying staff have issued a certificate of release to service. The CRS confirms that the maintenance was performed in accordance with Part 145 requirements and the applicable maintenance data. For aircraft, the CRS is entered in the aircraft technical log or equivalent. For components, it is documented on an EASA Form 1 authorised release certificate.
The certifying person must be satisfied that all required maintenance has been properly carried out before signing the CRS. This is a personal attestation, and the person signing bears regulatory responsibility. The CRS must include details of the maintenance carried out, the date of completion, and the identity and authorisation reference of the person signing.
Key requirements
A CRS must be issued before any aircraft is flown or any component is installed after maintenance. The CRS must contain a clear description of the work performed, including reference to the applicable maintenance data, any airworthiness directives or service bulletins complied with, and confirmation that all necessary inspections have been completed. The certifying staff member issuing the CRS must hold an appropriate authorisation from the organisation and a valid Part 66 licence where applicable.
Common compliance gaps
Common findings include CRS entries that lack sufficient detail to identify the work performed, missing references to the maintenance data revision used, and situations where certifying staff sign for work they did not personally verify was complete. Another issue is premature release, where the CRS is signed before all tasks, including independent inspections, have actually been completed and documented.
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