6.2 Independent Certifying Staff Privileges & Pilot-Owner Maintenance

6.2 Independent Certifying Staff Privileges & Pilot-Owner Maintenance

Quick Answer: EASA Part-ML (ML.A.801(b)(2)) introduces the revolutionary privilege for independent Part-66 licensed certifying staff (Categories B1, B2, B3, and L) to perform maintenance and issue a Certificate of Release to Service (CRS) directly on their personal authority, completely free from the requirement to hold an employment contract or company certification authorisation from an approved Part-145 or Part-CAO maintenance organisation. The real boundaries are in ML.A.502(b): independent certifying staff cannot issue an EASA Form 1 at all, cannot release the overhaul of components other than engines and propellers, and can release engine and propeller overhauls only for CS-VLA, CS-22 and LSA aircraft (and then only at aircraft level). Complementing this, ML.A.803 authorizes pilot-owners holding a valid EU pilot licence to perform and certify limited non-safety-critical maintenance tasks specified in Appendix II on their privately owned aircraft.

In commercial aviation and under classic Part-M rules, an aircraft maintenance licence issued under EASA Part-66 is purely a statement of personal technical qualification. Holding a Part-66 licence alone does not confer legal release privileges; the technician must additionally be employed by an approved maintenance organisation (Part-145 or Part-M Subpart F) and hold a formal, company-issued Certification Authorisation governed by the organisation's exposition. For General Aviation, this organizational mandate often created severe logistical bottlenecks, forcing aircraft owners to transport aircraft over long distances to approved facilities for routine servicing. Rule ML.A.801(b)(2) fundamentally alters this landscape by authorizing direct, independent release privileges for light aircraft.

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The Landmark Privilege: Independent Certifying Staff (Rule ML.A.801(b)(2))

ML.A.801(b) states that a Certificate of Release to Service for a Part-ML aircraft shall be issued, alternatively, by: (1) appropriate certifying staff on behalf of the approved maintenance organisation; (2) independent certifying staff; or (3) the pilot-owner in compliance with ML.A.803.

ML.1(c)(1) defines independent certifying staff as certifying staff who do not work on behalf of an approved maintenance organisation and who comply either with the requirements of Annex III (Part-66) or, for aircraft to which Part-66 does not apply, with the certifying staff requirements in force in the Member State of registry.

Beware of a widely circulated but incorrect paraphrase that bars independent certifying staff from complex maintenance tasks in Appendix II. Appendix II to Part-ML is the Limited Pilot-owner maintenance list and Appendix III is Complex maintenance tasks not to be released by the Pilot-owner — both address the pilot-owner, not independent certifying staff. The genuine limits on independent certifying staff are the component release rules in ML.A.502(b) and the scope of their own Part-66 licence category and ratings. An engineer holding an EASA Part-66 Aircraft Maintenance Licence in Category B1, B2, B3, or L can travel directly to an airfield, airstrip, or private hangar, perform scheduled maintenance or defect rectifications, and sign the aircraft CRS directly in the aircraft logbook—with zero organizational affiliation.

Privileges by Part-66 Licence Category

The scope of independent release privileges corresponds directly to the individual's Part-66 basic categories and aircraft type or group ratings:

• Category B1 (Mechanical): Privileged to perform and release maintenance on airframe structure, powerplant, mechanical systems, electrical systems, and avionic Line Replaceable Units (LRUs) requiring only simple tests to verify serviceability, on aircraft within their endorsed subcategory (e.g. B1.2 for piston aeroplanes).
• Category B2 (Avionics): Privileged to perform and release maintenance on avionic and electrical systems, instruments, navigation, communication, and radar equipment across Part-ML aircraft within their endorsed ratings.
• Category B3 (Light Piston Aeroplanes): Tailored specifically to non-pressurised piston aeroplanes of 2 000 kg MTOM and below. A Category B3 technician holds combined mechanical, structural, powerplant, electrical, and simple avionic LRU privileges for non-complex light aeroplanes.
• Category L (Light Aircraft): Tailored to sailplanes, powered sailplanes, hot-air balloons, gas balloons, and airships (subcategories L1 to L5). Category L holders exercise full independent release privileges within their specific subcategories.

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Scope, Boundaries, and Limitations of Independent Certifying Staff

While independent certifying staff enjoy unprecedented operational freedom under Part-ML, European airworthiness regulations impose strict technical boundaries to protect public safety:

1. Component Release Boundaries (ML.A.502(b))

The table in ML.A.502(b) is the controlling rule. Read at aircraft level (that is, without a Form 1), independent certifying staff may release:

• maintenance other than overhaul of components maintained to component maintenance data;
• overhaul of engines and propellers for CS-VLA, CS-22 and LSA aircraft; and
• all components and all types of maintenance where the work is done to aircraft maintenance data issued by the aircraft manufacturer.

They may not release the overhaul of components other than engines and propellers (that requires a component-rated maintenance organisation), nor the overhaul of engines and propellers for aircraft other than CS-VLA, CS-22 and LSA.

2. Complex Maintenance Tasks (Part-ML Appendix III) — a Pilot-Owner Restriction

Appendix III to Part-ML lists complex maintenance tasks not to be released by the Pilot-owner. This is the list that keeps the following work away from a pilot-owner and inside the tooling, engineering oversight and quality control systems of an approved organisation or, where the licence permits, professional certifying staff:

• Major Structural Modifications & Repairs: Modifications involving the cutting, riveting, or splicing of primary structural members (wing spars, fuselage longerons, engine bulkheads) requiring the use of jigs or fixtures to maintain structural alignment;
• Composite Primary Structure Rework: Structural bonded repairs on carbon-fiber, Kevlar, or glass-fiber primary structures exceeding minor surface delaminations;
• Propulsion Overhauls: The complete overhaul, disassembly, and rebuilding of piston engines, turbine engines, reduction gearboxes, or variable-pitch propeller hub assemblies;
• Primary Flight Control Surface Balancing: Complete rebuilding and dynamic re-balancing of primary control surfaces following structural rework.

3. Prohibition on Issuing EASA Form 1

Independent certifying staff cannot issue an EASA Form 1 (Authorized Release Certificate) for components or engines. An EASA Form 1 is a certificate that releases a component for general distribution, sale, or installation across European aviation, and European law reserves its issuance exclusively to approved maintenance organisations (Part-CAO, Part-145, or Part-21 POA).

• The Component Exception: An independent engineer can remove, maintain, and reinstall a component on the aircraft (for example, cleaning an engine starter motor or replacing an alternator brush set), but the release is issued on the aircraft CRS, covering the component only as installed equipment. The engineer cannot release the component into off-wing stock using a Form 1.

4. Maintenance Records and Independent CRS Format

When releasing maintenance independently, the technician does not possess an organizational approval number. Under ML.A.801(d) and AMC ML.A.801, the independent release entry in the aircraft logbook must include:

1. A detailed, unambiguous description of the maintenance tasks completed;
2. Exact references to the approved maintenance data used, including revision status (e.g. Cessna 172 Maintenance Manual, Chapter 12, Rev. 24);
3. The date of release and current total aircraft flight hours and landings/cycles;
4. The technician's Part-66 licence number (e.g. EASA.66.123456) and formal state of licence issue;
5. The certifying technician's full name and handwritten (or secure digital) signature;
6. The standardized Part-ML Certificate of Release to Service statement:

"Certifies that the work specified, except as otherwise specified, was carried out in accordance with Part-ML and in respect to that work the aircraft is considered ready for release to service."

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Pilot-Owner Maintenance Framework (Rule ML.A.803)

In addition to empowering licensed engineers, Part-ML preserves and refines the statutory concept of Pilot-Owner Maintenance under rule ML.A.803. This rule recognizes that competent aircraft owners can safely execute basic preventive servicing without requiring professional engineering assistance.

Legal Criteria to Qualify as a Pilot-Owner

To legally perform and release pilot-owner maintenance, an individual must satisfy three cumulative statutory requirements under ML.A.803(a):

1. Licensing Status (ML.A.803(a)(1)): The individual must hold a valid pilot licence or equivalent licence issued or validated by a Member State for the aircraft type or class rating (for example PPL, LAPL, CPL, ATPL, SPL or BPL). The licence must cover the aircraft actually being maintained.
2. Ownership Status (ML.A.803(a)(2)): The individual must own the aircraft, either as sole or joint owner, and that owner must be either:
   • (i) one of the natural persons on the registration form; or
   • (ii) a member of a non-profit recreational legal entity where that legal entity is specified on the registration document as owner or operator. That member must be directly involved in the decision-making process of the legal entity and be designated by it to carry out Pilot-owner maintenance.

Note the narrowness of route (ii): it is limited to non-profit recreational legal entities. A commercial limited company that owns an aircraft cannot simply nominate a pilot to act as a pilot-owner.

Where Pilot-Owner Maintenance Is Available (ML.A.803(b))

ML.A.803(b) frames this positively rather than as a list of prohibitions. The pilot-owner may issue a CRS after limited Pilot-owner maintenance as provided for in Appendix II where the aircraft is:

• operated under Annex VII (Part-NCO) to Regulation (EU) No 965/2012; or
• in the case of balloons, not operated under Subpart-ADD of Annex II (Part-BOP) to Regulation (EU) 2018/395; or
• in the case of sailplanes, not following Subpart DEC of Annex II (Part-SAO) to Regulation (EU) 2018/1976.

The practical consequence is the familiar one: aircraft on an air carrier AOC, in commercial specialised operations, or being used for commercial training outside Part-NCO fall outside those operating rules and therefore outside pilot-owner maintenance. But answer exam questions from the ML.A.803(b) operating-rule test, not from an invented list of exclusions.

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Permissible Task Scope: Part-ML Appendix II and AMC ML.A.803

Pilot-owner maintenance is not an unrestricted licence to tamper with an aircraft. European law establishes strict qualitative and technical boundaries to prevent accidents resulting from improper maintenance. Under Appendix II to Part-ML, pilot-owner maintenance must strictly conform to four basic principles:

1. Standard Preventive Maintenance: Tasks must involve routine servicing, cleaning, or simple component swaps;
2. No Flight Control Involvements: Tasks must never involve the disconnection, adjustment, rigging, or repair of primary flight control cables, push-pull rods, pulleys, or control surfaces;
3. No Safety-Critical Systems: Tasks must not involve high-pressure hydraulic systems, pitot-static calibrations, fuel tank internal seals, or structural airframe riveting;
4. No Special Tooling: Tasks must be executable using standard hand tools and standard torquing equipment without requiring specialized test rigs, electronic databus analyzers, or calibrated tensiometers.

Permitted Pilot-Owner Tasks vs Excluded Professional Tasks

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The Pilot-Owner Certificate of Release to Service (CRS)

When a pilot-owner completes an authorized task, they must formally certify the maintenance prior to the next flight. The release process is governed by rule ML.A.803(c):

1. Logbook Documentation: The pilot-owner must record the details of the maintenance directly in the aircraft logbook or technical log.
2. Mandatory Statement: The entry must include the exact regulatory reference and release statement:

"ML.A.803 Pilot-owner maintenance — Certifies that the work specified was carried out in accordance with Part-ML and in respect to that work the aircraft is considered ready for release to service."

1. Required Metadata (ML.A.803(c)): The entry must contain basic details of the maintenance carried out, the maintenance data used, the date on which the maintenance was completed, and the identity, signature and pilot licence (or equivalent) number of the pilot-owner issuing the certificate.
2. Legal Accountability: By signing the release, the pilot-owner assumes full legal responsibility under European civil aviation law for the quality, correctness, and airworthiness of the work performed. If a maintenance error (such as an improperly torqued oil filter or loose spark plug) leads to an in-flight engine failure, the pilot-owner is legally accountable.
3. Record Retention & Transfer: Under ML.A.305, pilot-owner maintenance records must be retained as part of the permanent continuing airworthiness records of the aircraft. When the aircraft is sold, all pilot-owner release entries must be transferred to the purchaser.

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Comparison: Release Pathways under EASA Part-ML

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Practical Maintenance Scenario: Tyre Replacement and Spark Plug Service

Operational Context

A pilot-owner operates a Robin DR400 wooden light aircraft. During a pre-flight inspection, the pilot notices that the left main landing gear tyre exhibits heavy cord wear and two spark plugs are fouled, causing a magneto drop during run-up.

Division of Privileges:

1. Option 1 — Pilot-Owner Action: Under ML.A.803 and Appendix II, the pilot-owner can personally jack the left wing, remove the wheel assembly, install a new inner tube and tyre, clean the spark plugs, check gap tolerances with a feeler gauge, torque the plugs with a calibrated wrench, and sign the pilot-owner CRS in the engine and airframe logbooks under ML.A.803.
2. Option 2 — Independent Certifying Staff Action: If the pilot-owner lacks tools, they can hire an independent Part-66 Category B1.2 or B3 engineer. The engineer performs the work and signs an independent CRS citing their Part-66 licence number under ML.A.801(b)(2). No Part-145 or Part-CAO approval is required.
3. Prohibited Escalation: If upon jacking the aircraft the technician discovers a cracked wooden wing spar attach fitting, the pilot-owner is out of scope immediately: Appendix III to Part-ML lists structural repair among the complex maintenance tasks not to be released by the pilot-owner, and it is nowhere in the Appendix II limited list. Whether the independent engineer may release the repair depends on the licence category and ratings held and on the ML.A.502(b) component rules; if a component has to be overhauled off-wing or a Form 1 is needed, the work must go to an approved Part-CAO or Part-145 organisation.

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EASA Module 10 Examination Tips & Traps

• Independent Certifying Staff Privilege: Remember that Part-66 B1, B2, B3, and L engineers can release Part-ML maintenance independently without a company certification authorisation from an approved organisation.
• The EASA Form 1 Trap: An independent certifying engineer can never issue an EASA Form 1 for a component. If an exam question asks whether an independent engineer can issue a Form 1 for an overhauled magneto, the answer is an absolute no.
• Appendix II vs Appendix III: Appendix II to Part-ML is Limited Pilot-owner maintenance; Appendix III is Complex maintenance tasks not to be released by the Pilot-owner. Both are pilot-owner rules. The limits on independent certifying staff come from ML.A.502(b) and from their own licence category and ratings.
• Pilot-Owner Qualification: A pilot-owner must hold both a valid pilot licence and registered aircraft ownership (sole or joint). A pilot renting an aircraft cannot perform pilot-owner maintenance.
• Flight Control Inviolability: Pilot-owners can never adjust or rig primary flight controls. If an exam option mentions "adjusting elevator cable tension" as a pilot-owner task, it is an incorrect distractor.
• The Non-Profit Route: Where the aircraft is registered to a legal entity rather than an individual, pilot-owner maintenance is only available through the non-profit recreational legal entity route in ML.A.803(a)(2)(ii), and only for a member who is directly involved in the entity's decision-making and designated by it to carry out the maintenance.