Part-ML Airworthiness Review Checklist: From Aircraft Maintenance Program to ARC Renewal

Under Part-ML, an aircraft needs a valid airworthiness review certificate (ARC), issued on EASA Form 15c after a satisfactory airworthiness review and valid for 1 year (ML.A.901(a)). The review checks that the aircraft maintenance program (AMP) was followed, that the 100-hour/annual inspections were done within tolerance, that ADs and defects are under control, and that the aircraft physically matches its records. This checklist walks through each step in order.

It is written for American owners of light aircraft on an EU Member State register, U.S. buyers bringing an aircraft onto such a register, and staff at CAMOs and CAOs. All references are to Annex Vb (Part-ML) of Regulation (EU) No 1321/2014 as consolidated on 22 February 2026, and to EASA's continuing airworthiness FAQ. FAA inspection and certification rules are not part of this source material.

Step 1: Get the aircraft maintenance program right

Everything starts with the AMP: ML.A.302(a) says the maintenance of each aircraft is organised in accordance with one. ML.A.302(b) gives two routes:

• Declared by the owner, where continuing airworthiness is not managed by a CAMO or CAO. EASA's FAQ adds that a declared AMP does not need to be sent to the competent authority.
• Approved by the CAMO or CAO that manages the aircraft's continuing airworthiness.

Whoever declares or approves the AMP must keep it updated. Its content (ML.A.302(c)) identifies the owner and the aircraft, including engine and propeller, and is based either on the minimum inspection program (MIP) in point (d), or on the instructions for continuing airworthiness (ICA) issued by the design approval holder or by the declarant of a declaration of design compliance.

EASA's FAQ explains the practical difference between the two routes. A declaring owner may, on his or her own responsibility, deviate from scheduled maintenance recommendations without justifying it, except for mandatory requirements. A CAMO or CAO must justify and record deviations. In both cases, when the AMP is not based on the MIP, deviations from the ICA must not end up less restrictive than the corresponding MIP task, and mandatory items such as repetitive ADs or the airworthiness limitation section must always be included.

Step 2: Keep inspections inside the MIP interval

ML.A.302(d)(1) fixes the MIP intervals. For aeroplanes, touring motor gliders and balloons it is every annual or 100-hour interval, whichever comes first, with a tolerance of 1 month or 10 hours. For sailplanes and powered sailplanes other than TMGs it is annual, with a 1-month tolerance. In both cases, “the next interval shall be calculated as from the time the inspection takes place.”

A worked example, applying only that text: an inspection falls due at 1,200 hours and is performed at 1,207 hours, inside the 10-hour tolerance. The next 100-hour interval runs from 1,207, so the following inspection is due at 1,307 hours (1,207 + 100), unless the annual limit arrives first. EASA's FAQ confirms that for Part-ML, when the tolerance is used, the next interval is counted from the accomplishment date, not from the original due date.

The MIP also lists what each inspection must cover, as applicable to the type: servicing required by the design approval holder, markings, weighing records, transponder test, pitot-static functional test, engine run-up checks (power, rpm, magnetos, fuel and oil pressure, temperatures) and a condition-and-attachment inspection of every listed area, from airframe and controls to propeller and ballistic rescue system.

Step 3: Bring the records up to date

The airworthiness review is first a documented review of records. ML.A.305(d) says those records must show the current status of:

• ADs and measures mandated by the competent authority;
• modifications, repairs and other DAH maintenance recommendations;
• compliance with the AMP;
• service-life-limited components;
• the mass and balance report;
• deferred maintenance.

Every CRS should already be in the records: ML.A.305(a) requires the entry no later than 30 days after the maintenance was completed. Detailed maintenance records are kept for at least 36 months after release to service (ML.A.305(h)(1)).

Step 4: Choose who performs the review

ML.A.901(b) lists who may perform the review and issue the ARC:

An independent reviewer with a Part-66 license may review aircraft registered in any Member State; one holding only a national qualification is limited to that Member State, and such ARCs do not benefit from mutual recognition on transfer. The authorization for independent reviewers (ML.A.904(d)) lasts 5 years, provided the holder performs at least 1 airworthiness review every 12 months.

Step 5: The review itself

ML.A.903(a) sets the records review. The reviewer verifies that flight hours and cycles are recorded; the flight manual matches the configuration and latest revision; all AMP maintenance is done; known defects are corrected or deferred in a controlled way; ADs are applied and registered; modifications and repairs comply with Part 21 or Part 21 Light; life-limited parts are within limits; all maintenance is certified; the mass-and-balance statement is valid where required; the aircraft matches its latest approved type design; and, if required, a matching noise certificate is held.

A physical survey follows (ML.A.903(b)-(c)): markings and placards, compliance with the flight manual, configuration against documentation, no unaddressed evident defect, and no inconsistency with the records. Reviewers not qualified under Part-66 must be assisted by qualified staff.

1. The review may be brought forward by up to 90 days without breaking the review pattern, so the physical survey can coincide with a maintenance check (ML.A.903(d)).
2. The ARC is only issued once all findings are closed and any AMP discrepancy is addressed (ML.A.903(e)). EASA's FAQ is explicit: no ARC with open findings.
3. A copy of the ARC goes to the Member State of registry within 10 days (ML.A.903(f)).
4. Airworthiness review tasks shall not be subcontracted (ML.A.903(g)).
5. The AMP's effectiveness may be reviewed at the same time by the same person (ML.A.903(h)); the FAQ notes that Part-ML requires an annual AMP review.

Step 6: Renewal, extension and what voids the ARC

After a full review, the ARC is valid for 1 year. A CAMO or CAO may instead extend it up to two consecutive times, one year each, if it has continuously managed the aircraft for the previous 12 months, the aircraft has been maintained by approved organizations over that period (pilot-owner tasks included), and it has no reason to doubt airworthiness (ML.A.901(c)). An extension can be brought forward by up to 30 days (ML.A.901(d)); the FAQ adds that anticipating by more than 30 days resets the expiry to one year after the extension date.

The ARC becomes invalid if it, the airworthiness certificate or the type certificate is suspended or revoked, or if the aircraft leaves a Member State register (ML.A.902(a)). Even with a valid ARC, the aircraft must not fly after an unaddressed exceedance, accident damage or non-compliant modification (ML.A.902(b)).

Bringing an aircraft in from outside the EU

For a U.S. buyer moving an aircraft onto a Member State register from a third country, ML.A.906 requires an application for a new airworthiness certificate, a satisfactory airworthiness review for any aircraft other than new, and all maintenance done to the approved or declared AMP. The reviewer then issues the ARC and sends a copy to the authority of the Member State of registry. Questions like “Who can actually check it's still airworthy each year and hand me the certificate?” can be put to the Part-ML knowledge base, which answers with the provision cited.

This checklist explains the EU rule and is not a substitute for the airworthiness review staff's judgment on a given aircraft. Primary sources: EUR-Lex consolidated text and EASA's FAQ. EASA's AMC/GM to Part-ML are not in the knowledge base.