Definition
Release to service is the legal moment an aircraft transitions from "under maintenance" back to "airworthy and operable." Under EASA Part-145 145.A.50 (and Part-M M.A.801 for aircraft outside the Part-145 environment), the Certificate of Release to Service is signed by certifying staff licensed under Part-66 with the appropriate category and rating for the work performed, and it explicitly states that the work was performed in accordance with approved data and that no condition is known that would render the aircraft unsafe.
Under the FAA system (14 CFR §43.5 and §43.7), the equivalent action is the maintenance entry signed by an authorized person — A&P mechanic, IA, repair station with appropriate certification — recording the work performed, the date completed, the signature and certificate number of the person performing or supervising the work, and a statement that the aircraft is approved for return to service with respect to the work performed. The phrase "approved for return to service" is a regulated phrase under §43.9, and signing it falsely is a separate violation under §43.12.
The scope of a release matters legally. A CRS or return-to-service signature certifies the specific work performed — not the overall airworthiness of the aircraft. A mechanic signing the release after a tire change has not certified that the rest of the aircraft is airworthy; that signature only certifies the tire change. The aircraft's overall airworthiness is the operator's responsibility under §91.403 / M.A.301, and the operator relies on the cumulative effect of every release-to-service plus every recurring inspection to maintain that airworthiness.
For parts, an analogous concept applies. A part returned from overhaul carries an EASA Form 1 (or the equivalent FAA Form 8130-3) — the certifying tag that documents the work performed by a Part-145/Part 145 organization and certifies the part as serviceable. A part installed without a valid Form 1 / 8130-3 cannot have a valid release-to-service signed for the installation; the absence of the part-release tag breaks the audit chain.
Why It Matters for Flight Schools
Release-to-service discipline is the most heavily audited area of maintenance documentation. Competent authority inspectors will sample work orders and trace each release-to-service back through the supporting evidence: were the certifying staff appropriately Part-66-licensed for the rating of the work? Were the parts traceable to their Form 1 / 8130-3? Were any required inspector signoffs present? Was the certificate signed by hand (or with appropriate electronic-signature controls) and dated correctly?
The failure pattern is the rushed CRS at end-of-shift or end-of-month. A maintenance check is essentially complete at 11pm on the last day of the month. The certifying staff member signs the CRS so the aircraft can be released for the next day's flying. A subsequent records review reveals that one Form 1 was not yet attached, one inspector signoff was missed, one task was complete-in-practice-but-unsigned. The aircraft has flown 40 hours since the CRS, and the operator now has to disclose to the regulator and ground the aircraft pending corrective action. The cost is much greater than the cost of an extra day of maintenance.
How Aviatize Handles This
Aviatize's maintenance execution module enforces release-to-service preconditions in software. The CRS cannot be signed until every task on the work order is signed off by an appropriately rated technician; every inspector signoff that the work order requires is in place; every part fitted has a Form 1 / 8130-3 attached and traceable; every NRC raised during the work is either signed off complete or formally deferred (with the deferral linked to the appropriate MEL or operator-approved deferral procedure); and the certifying staff member's Part-66 license — with the category and rating relevant to the work — is current.
When all preconditions are met, the platform produces the CRS document with the structured content the regulator audits for: the aircraft identification, the work performed (referencing the source task cards), the certifying staff member's name and license number, the date and time, and the explicit statement of release-to-service in the text the relevant regulation prescribes. The corresponding logbook entry is generated automatically, the dispatch system unlocks the aircraft for booking, and the audit trail is complete the moment the signature is captured — not reconstructed at audit time.