6.3 Combined Airworthiness Organisations (Part-CAO) Structure & Privileges

6.3 Combined Airworthiness Organisations (Part-CAO) Structure & Privileges

Quick Answer: Annex Vd (Part-CAO) to Regulation (EU) No 1321/2014, introduced by Commission Implementing Regulation (EU) 2019/1383, consolidates the previously separated Part-M Subpart F (maintenance organisation) and Part-M Subpart G (CAMO) into a unified, lightweight approval for general aviation. A Part-CAO can hold up to four integrated privileges under a single approval certificate: 1) maintenance of aircraft and components; 2) continuing airworthiness management; 3) airworthiness reviews (directly issuing or extending EASA Form 15c for Part-ML aircraft); and 4) issuance of Permits to Fly. Operational procedures are unified in a single Combined Airworthiness Exposition (CAE - CAO.A.025), and a small CAO as defined in CAO.A.100(e) can replace the quality system with regular organisational reviews under CAO.A.100(f), subject to competent authority approval and on condition that it does not contract continuing airworthiness management tasks to other parties.

Historically, the European continuing airworthiness framework forced General Aviation businesses into an artificial operational divide. An aeroclub or maintenance workshop wishing to provide comprehensive services to aircraft owners—both maintaining the aircraft in a hangar and managing its continuing airworthiness paperwork—had to seek and maintain two distinct regulatory approvals under Regulation (EC) No 2042/2003: Part-M Subpart F (maintenance organisation) and Part-M Subpart G (CAMO). This required maintaining two separate manuals (a Maintenance Organisation Exposition / MOE and a Continuing Airworthiness Management Exposition / CAME), undergoing duplicate authority audits, paying dual surveillance fees, and maintaining two separate quality assurance systems. To eliminate this duplication, the European Commission introduced Annex Vd (Part-CAO), formally phasing out Part-M Subparts F and G.

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Genesis and Statutory Architecture of Part-CAO (Annex Vd)

Introduced by Commission Implementing Regulation (EU) 2019/1383, Part-CAO entered into force in March 2020 with a structured transition period that concluded on 24 September 2021. After this date, all former Part-M Subpart F and Subpart G approvals for light aircraft ceased to exist, having transitioned into either Part-CAO (Annex Vd) for light aviation or Part-CAMO (Annex Vc) for commercial and complex air transport.

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|              REGULATORY REORGANIZATION UNDER REGULATION (EU) 2019/1383            |
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| FORMER REGULATORY STRUCTURE (PRE-2020):                                           |
| • Part-M Subpart F: Maintenance organisation for other-than-large aircraft       |
| • Part-M Subpart G: CAMO for all aircraft types (airlines and light aircraft)     |
|                                                                                   |
| MODERN RESTRUCTURED FRAMEWORK:                                                    |
| • Part-145 (Annex II):  Maintenance organisations for complex aircraft & CAT     |
| • Part-CAMO (Annex Vc): Continuing airworthiness for complex aircraft & CAT (SMS)|
| • Part-CAO (Annex Vd):  Combined Maintenance + CAMO for General Aviation         |
| • Part-ML (Annex Vb):   Continuing airworthiness rules for light aircraft         |
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Part-CAO was deliberately crafted around the operational reality of small aviation enterprises. By merging physical maintenance with airworthiness management into a single legal entity, it allows seamless coordination between the technician on the hangar floor and the technical records manager in the office.

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Technical Scope and Applicability of Part-CAO

Rule CAO.A.010 and rule CAO.A.020 specify the aircraft categories and component types eligible for inclusion within a Part-CAO approval:

• Part-ML Aircraft Fleet: Aeroplanes ≤ 2 730 kg MTOM, rotorcraft ≤ 1 200 kg MTOM (certified for up to 4 occupants), sailplanes, powered sailplanes, balloons, and airships.
• Other-than-Complex Motor-Powered Aircraft (Other-than-CMPA): A Part-CAO may also be approved to manage and maintain other-than-complex aircraft that exceed Part-ML thresholds, such as:
  • Piston and turboprop aeroplanes up to 5 700 kg MTOM (e.g. Cessna 400 series, Piper PA-31 Navajo, Beechcraft King Air 90/200 series) not operated in CAT;
  • Single-engine and multi-engine turbine helicopters up to 3 175 kg MTOM (e.g. Bell 206 JetRanger, Airbus H125/AS350, Leonardo AW109) not operated in CAT.
• Components & Engines: Maintenance, overhaul, repair, and release (via EASA Form 1) of reciprocating engines, turbine engines (if approved), propellers, and mechanical/avionic components.

The Inviolable Exclusion: Complex Aircraft and CAT

A Part-CAO is strictly prohibited from holding approval for:

1. Complex Motor-Powered Aircraft (CMPA): High-speed multi-engine transport jets (e.g. Airbus A320, Boeing 737, Bombardier Global Express, Dassault Falcon 7X). These require Part-145 for maintenance and Part-CAMO for management.
2. Commercial Air Transport (CAT): Any aircraft listed on the Air Operator Certificate (AOC) of an air carrier licensed under Regulation (EC) No 1008/2008.

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The Four Core Privileges of Part-CAO (Rule CAO.A.095)

The cornerstone of Part-CAO is the concept of combined privileges. Under rule CAO.A.095, an organisation can hold any combination of four distinct continuing airworthiness privileges under a single approval certificate issued by its competent National Aviation Authority:

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|                     THE FOUR CORE PRIVILEGES OF PART-CAO (CAO.A.095)              |
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| 1. MAINTENANCE PRIVILEGES:                                                        |
|    • Maintain aircraft and components within approved scope                       |
|    • Perform complex maintenance tasks listed in Part-ML Appendix III             |
|    • Issue aircraft Certificates of Release to Service (CRS)                      |
|    • Issue EASA Form 1 for maintained/overhauled components                       |
|                                                                                   |
| 2. CONTINUING AIRWORTHINESS MANAGEMENT PRIVILEGES:                                |
|    • Manage continuing airworthiness of Part-ML and non-complex aircraft          |
|    • Develop and approve Aircraft Maintenance Programmes (AMPs)                   |
|    • Manage life-limited parts (LLPs), ADs, SBs, and airworthiness records         |
|                                                                                   |
| 3. AIRWORTHINESS REVIEW PRIVILEGES:                                               |
|    • Perform physical and documentary airworthiness reviews                       |
|    • Directly issue or extend Airworthiness Review Certificate (EASA Form 15c)    |
|    • Issue recommendations for EASA Form 15a (NAA issue)                         |
|                                                                                   |
| 4. PERMIT TO FLY PRIVILEGES:                                                      |
|    • Issue Permits to Fly (EASA Form 20b) under Part-21 (21.A.711(d))             |
|    • Authorize ferry, test, or relocation flights with approved flight conditions  |
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Detailed Breakdown of Privileges:

1. Maintenance Privileges (CAO.A.095(a)): The organisation may maintain any aircraft or component listed on its approval certificate at approved base locations or away from base (line support). It may perform the complex maintenance tasks that Appendix III to Part-ML keeps away from the pilot-owner (such as engine overhauls or wing spar replacements), and the component overhauls that ML.A.502(b) reserves to rated organisations, and it holds statutory authority to issue EASA Form 1 for components.
2. Continuing Airworthiness Management Privileges (CAO.A.095(b)): The organisation acts as the CAMO for light aircraft. It tracks aircraft flight hours, monitors Airworthiness Directives (ADs) and manufacturer Service Bulletins (SBs), schedules required maintenance, and develops/approves the Aircraft Maintenance Programme (AMP) for contracted owners.
3. Airworthiness Review Privileges (CAO.A.095(c)): The organisation can perform airworthiness reviews (reviewing records and physically surveying the aircraft). For Part-ML aircraft, the Part-CAO directly issues an Airworthiness Review Certificate (ARC - EASA Form 15c) or extends it. For non-Part-ML aircraft (e.g. King Air 200 under Part-M), it issues an airworthiness review recommendation to the NAA for the issuance of a Form 15a.
4. Permit to Fly Privileges (CAO.A.095(d)): Under rule 21.A.711(d) of Part-21, a Part-CAO holding this privilege can directly issue a Permit to Fly (EASA Form 20b) for an aircraft registered in a Member State when the aircraft does not meet certified airworthiness standards (e.g. flight to a maintenance base with an expired ARC or deferred landing gear issue), provided the flight conditions have been approved by EASA or the competent authority.

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The Combined Airworthiness Exposition (CAE - Rule CAO.A.025)

Under Part-CAO, the administrative separation between maintenance and CAMO documentation is dissolved. Rule CAO.A.025 mandates that the organisation establish and maintain a single comprehensive operational manual: the Combined Airworthiness Exposition (CAE).

Structure and Core Content of the CAE

The CAE is approved by the competent National Aviation Authority and serves as the binding operational rulebook for the organisation. It contains five primary sections:

1. Part 1 — General Management: Contains the Accountable Manager's signed corporate commitment to comply with Regulation (EU) No 1321/2014; safety and quality policy; nominated management personnel and organizational chart; description of facilities, hangars, workshops, and office spaces; detailed scope of work; and procedures for amending the CAE.
2. Part 2 — Maintenance Procedures: Details work order acceptance, maintenance planning, access to approved maintenance data (AMMs, ADs), tooling control and calibration schedules, component storage and acceptance (verifying EASA Form 1), fabrication of parts in course of maintenance, defect rectification, independent inspection procedures for safety-critical tasks, and Certificate of Release to Service (CRS) sign-off protocols.
3. Part 3 — Continuing Airworthiness Management Procedures: Details procedures for developing and approving Aircraft Maintenance Programmes (AMPs); tracking airframe, engine, and propeller hours/cycles; managing mandatory continuing airworthiness requirements (AD tracking); life-limited component control; technical records retention; and contracting maintenance to external facilities.
4. Part 4 — Airworthiness Review & Permit to Fly Procedures: Sets forth the qualification and competency criteria for airworthiness review staff; physical inspection checklists; Form 15c issuance and extension procedures; airworthiness review recommendations to NAAs; and procedures for issuing Permits to Fly pursuant to approved flight conditions.
5. Part 5 — Quality / Compliance Monitoring System: Details the internal compliance monitoring programme, audit scheduling, auditor independence, deficiency reporting, corrective action tracking, or the procedures governing the Organisational Review in small CAOs.

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Management Personnel and the Proportional Quality System

Part-CAO establishes a streamlined personnel hierarchy designed to eliminate unnecessary corporate overhead while maintaining clear lines of airworthiness accountability.

Management Hierarchy

• The Accountable Manager (CAO.A.035(a)): A single corporate leader possessing ultimate financial and corporate authority to ensure that all maintenance and airworthiness management activities are adequately financed and conducted in strict compliance with Part-CAO.
• Nominated Persons (CAO.A.035(b)): A person or group of persons representing the technical management of the organisation, responsible for: 1) Maintenance management; 2) Continuing airworthiness management; and 3) Compliance monitoring.
• Role Combination Flexibility: In large commercial Part-145 organisations, managers must remain strictly segregated to prevent conflicts of interest. Under Part-CAO, rule CAO.A.035(b) explicitly permits the combination of nominated roles. In a small aeroclub workshop, a single suitably qualified individual may serve as both the Head of Maintenance and the Head of Continuing Airworthiness, or the Accountable Manager may personally hold a technical nominated post.

The Small Organisation Review Option (CAO.A.100)

In commercial aviation, Part-145 and Part-CAMO mandate a full-scale, fully independent Quality Assurance / Compliance Monitoring System, requiring dedicated full-time internal auditors who are strictly independent of the work being audited. For a small workshop with five mechanics, hiring independent auditors is economically impossible.

Rules CAO.A.100(e) and (f) provide a pragmatic regulatory solution: The Organisational Review.

• Definition of a small CAO (CAO.A.100(e)): a CAO is a small CAO when any one of the following is met:
  1. the scope of the CAO contains only aircraft covered by Part-ML; or
  2. the CAO does not exceed 10 full-time-equivalent staff involved in maintenance; or
  3. the CAO does not exceed 5 full-time-equivalent staff involved in continuing airworthiness management.
• Mechanism (CAO.A.100(f)): in the case of a small CAO the quality system may be replaced by regular organisational reviews, subject to the approval of the competent authority. The rule says "regular" — it does not itself fix a 12-month cycle, so follow the interval agreed with the authority and written into the CAE.
• The Price of the Concession: a small CAO using organisational reviews shall not contract continuing airworthiness management tasks to other parties. This condition is frequently omitted from summaries and is a favourite examination discriminator.
• Record Retention (CAO.A.100(c)): the monitoring records must be retained for at least the previous 2 years.
• Execution: The review may be conducted by the Accountable Manager or an assigned senior staff member. The review verifies that:
  • Maintenance job cards and CRS releases strictly adhere to CAE procedures;
  • Technical records, logbooks, and AMP approvals are completely documented;
  • Measuring tools and torque wrenches are calibrated within documented cycles;
  • Airworthiness review files justifying Form 15c certificates are properly archived;
  • Occurrence reports have been submitted to the NAA and TC holders within 72 hours.
• Accountability: The findings of the Organisational Review are presented directly to the Accountable Manager, who signs off on mandatory corrective action plans.

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Comparative Matrix: Part-CAO vs Part-145 vs Part-CAMO

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Practical Maintenance Scenario: Transitioning an Aeroclub to Part-CAO

Operational Context

A regional aeroclub in Bavaria operates six aircraft: four Cessna 172s used for flight training and two Piper PA-34 Senecas used for multi-engine ratings. The aeroclub previously maintained two separate approvals: Part-M Subpart F (Approval DE.MF.0123) for workshop maintenance and Part-M Subpart G (Approval DE.MG.0123) for continuing airworthiness management.

Regulatory Conversion to Part-CAO:

1. Unified Approval: The aeroclub applies to the Luftfahrt-Bundesamt (LBA) for conversion to Part-CAO with combined maintenance and CAMO privileges, plus airworthiness review privileges.
2. Consolidated Exposition: The club drafts a single Combined Airworthiness Exposition (CAE) combining their former MOE and CAME. Tooling calibration procedures, technician authorisations, AMP management, and aircraft technical log control are housed in one manual.
3. Quality Simplification: The aeroclub qualifies as a small CAO on two independent CAO.A.100(e) grounds — its scope contains only Part-ML aircraft, and it employs four full-time technicians (below the 10 FTE maintenance threshold). The LBA therefore approves regular organisational reviews under CAO.A.100(f), on condition that the club does not contract its continuing airworthiness management tasks to any other party. The club disbands its expensive outsourced independent audit contract and institutes an annual internal review conducted by the Accountable Manager.
4. Operational Efficiency: When a Cessna 172 completes its 100-hour MIP inspection in the workshop, the Part-CAO certifies the maintenance (CRS), conducts an airworthiness review, and directly issues an Airworthiness Review Certificate (EASA Form 15c) on the spot, allowing immediate return to flight training.

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EASA Module 10 Examination Tips & Regulatory Traps

• The Four Privileges: Exam questions frequently test the four core privileges of Part-CAO: 1) Maintenance, 2) Continuing Airworthiness Management, 3) Airworthiness Review, and 4) Permit to Fly.
• Exposition Document: Remember that Part-CAO uses the CAE (Combined Airworthiness Exposition) under CAO.A.025. Do not confuse it with an MOE (Part-145) or CAME (Part-CAMO).
• Former Subparts Replaced: Part-CAO replaced Part-M Subpart F (maintenance) and Part-M Subpart G (CAMO) for general aviation. The transition deadline ended on 24 September 2021.
• The Small CAO Rule: CAO.A.100(e) gives three alternative triggers — Part-ML-only scope, 10 or fewer FTE in maintenance, or 5 or fewer FTE in continuing airworthiness management. Any one is enough. CAO.A.100(f) then allows regular organisational reviews instead of a quality system, subject to authority approval, and only if the CAO does not contract continuing airworthiness management tasks out.
• ARC Form Numbers: Memorize the form numbers: EASA Form 15c is issued by a Part-CAO for Part-ML aircraft; EASA Form 15a is issued by the NAA (for which a CAO issues a recommendation); and EASA Form 15b is the classic Part-M CAMO ARC.
• Complex Aircraft Exclusion: A Part-CAO can never maintain or manage complex motor-powered aircraft (CMPA) or aircraft operated in Commercial Air Transport (CAT) under an airline AOC.