October 10, 2025

Steven Bentley

Sofema Aviation Services (SAS) Consider in depth the relationship between a part 21 G organisation and a part 21J organisation, how to create a new business and gain a part 21G certificate.  How to proceed if the EASA Part 21G does not have a 21J partner.

Introduction 21G ↔ 21J Roles & Responsibilities

  • 21J (DOA) owns/controls the approved design data (type certificates, STCs, repair/major change approvals, ETSOs, etc.) and supports continued airworthiness. EASA requires DOA–POA coordination so that production always matches the approved/controlled design.
  • 21G (POA) demonstrates conformity to the applicable design data, releases items (EASA Form 1) or whole aircraft (Form 52  C of A), and holds production privileges and obligations under Subpart G.

EASA explicitly requires satisfactory coordination between design and production (DOA↔POA). This is codified in 21.A.4 and 21.A.133 with AMCs that describe the documented arrangement linking you (POA) to the design approval holder (DAH).

If you do not have a 21J partner: what can you manufacture?

Without a DOA of your own (21J) or a documented arrangement with a design approval holder (TC/STC/ETSO/repair approval holder), a 21G cannot show conformity to approved design data for most aviation parts—so you cannot release them on EASA Form 1 under 21.G. You still have these options:

Standard parts (per AMC 21.A.303(c))

    • These are parts whose design/manufacture/inspection/marking data are in the public domain via an officially recognised standard (e.g., fasteners to NAS/MS, certain generic components). For standard parts, Form 1 is not required for installation eligibility (derogation in 21.A.307(b)(1)); a supplier/manufacturer declaration is sufficient if the installer holds that document.

Build-to-print for a DAH under a documented arrangement

    • If you’re producing to someone else’s approved design (TC/STC/ETSO/repair), you must put in place the 21.A.133(d) link/arrangement. This enables you to receive controlled design data, get Direct Delivery Authorisation (when applicable), control configuration, and legitimately issue EASA Form 1.

Subpart F (Letter of Agreement) as a stepping stone

    • If you’re not yet ready for EASA Part 21G, you can request Subpart F (EASA Form 65 Letter of Agreement) for low-volume/simple technology or transitional needs—but long-term production is expected to migrate to 21G.

ETSO route (Subpart O)

    • You could pursue ETSO authorisation for an appliance and then produce it (still requires appropriate design capability/arrangements).

To Issue EASA Form 1

To issue Form 1 for anything other than standard parts (or narrowly exempted cases), a 21G must be linked to the design holder via 21.A.133(d) documented arrangements—or be the design holder.

Step-by-step: How to gain a 21G approval (POA)

Step 1 — Define your scope & sourcing of design data

  • Write a clear scope: which products/parts/appliances and to which applicable design data (TC/STC/ETSO/repair approvals). This will become your Terms of Approval.
  • If you do not have your own DOA, line up documented arrangements with the DAH(s) whose designs you will build (see Step 3).

Step 2 — Apply (21.A.134) and plan the means of compliance

  • Submit your application under 21.A.134 and explain your means of compliance (21.A.134A).

Step 3 — Put in place the DOA–POA arrangement (21.A.133(d))

  • The AMC provides a sample arrangement listing responsibilities for transfer of design data, configuration control, dealing with deviations, non-conformances, continuing airworthiness support, and Direct Delivery Authorisation if applicable. This is mandatory whether DOA and POA are in the same legal entity or separate.

Step 4 — Build your Production Management System (21.A.139)

  • Establish and document your production management system (policy, processes, controls, independent monitoring, internal audit, risk controls, supplier control, configuration, records, competence, etc.).
  • Include the Information Security Management System (ISMS) clause (21.A.139A) if required by scope.

Step 5 — Develop your POE (21.A.143)

  • Your Production Organisation Exposition must describe your organisation, scope, procedures, interfaces (including the DOA–POA arrangement), supplier control, release procedures (Form 1/52/53), permit to fly procedure (if sought), etc.

Step 6 — Prove Resources & Competence (21.A.145)

  • Demonstrate sufficient facilities, equipment, tools, staff competence, certifying staff, and the independence/authority of the compliance function.

Step 7 — Inspection, testing & conformity processes (21.A.126–21.A.130)

  • Define inspection/test regimes, management of non-conformances and statement of conformity leading to Form 1/Form 52 issuance.

Step 8 — Define Privileges sought (21.A.163)

  • Typical privileges: conduct production, issue EASA Form 1, obtain C of A for new aircraft with Form 52, maintain new aircraft you produced and issue Form 53, and (optionally) issue permits to fly under agreed procedures. Ensure your POE covers any maintenance/permit-to-fly privileges you request.

Step 9 — Understand Obligations (21.A.165) and Validity (21.A.159)

  • Use the POE and referenced docs as basic working documents, remain open to authority investigations, and maintain satisfactory control of manufacture to keep the approval valid.

Step 10 — Approval & Terms of Approval (21.A.151)

  • Your authority EASA  will issue the POA certificate and Terms of Approval listing scope, products, and/or categories you can release under 21.A.163.

Step 11 — Manage changes (21.A.147 / 21.A.148 / 21.A.153)

  • Significant PMS changes or location changes need prior approval; changes to Terms of Approval require application.

Your initial production portfolio (no in-house 21J)

Viable near-term build plan without your own DOA:

  • Standard parts line (fasteners/hardware to recognised standards) with robust traceability and supplier QA. These are eligible for installation without Form 1 when the installer holds your declaration—use this to build revenue/capability while your 21G matures.
  • Build-to-print for one or more DAHs (TC/STC/ETSO/repair approval holders) under 21.A.133(d) arrangements so you can issue Form 1. Start with non-critical parts and scale to critical/primary structure as you demonstrate system maturity (and as the DAH approves).
  • Consider Subpart F for early prototypes/low volume (time-boxed) while your 21G system, POE, and staff authorisations are finalised.

Typical issues & challenges (and how to avoid them)

Design link gaps

  • Issue: Missing or weak DOA–POA arrangement; uncontrolled design data changes; unclear configuration baselines.
  • Fix: Use the AMC sample arrangement and ensure end-to-end processes for data transfer, change control, concessions/deviations, and Direct Delivery Authorisation where needed.

Form 1 eligibility mistakes

  • Issue: Issuing Form 1 without approved design data, or for a standard part (not needed).
  • Fix: Train certifying staff on 21.A.130/21.A.307 and your release criteria; do not “upgrade” standard parts with Form 1 unless design/eligibility requires it.

Supplier control & traceability

  • Issue: Incomplete incoming inspection, weak control of outsourced special processes.
  • Fix: Embed strong supplier approval & surveillance within your 21.A.139 PMS; define receiving inspection, process qualification, and certificates/CoCs content requirements.

Non-conformances & concessions

  • Issue: Ad-hoc fixes; no formal link to DOA for design deviations or repairs.
  • Fix: Route concessions, rework, and repairs via procedures aligned with the DOA; never release product that deviates from approved design without approved deviation.

Keeping the approval valid

  • Issue: Authority identifies lack of “satisfactory control of manufacture.”
  • Fix: Maintain robust internal audit, competency management, and CAPA; examples of what “unsatisfactory” looks like are listed under GM 21.A.159(a)(3)—use them as a self-check.

Best-practice blueprint (what great looks like)

  • Early, formal DOA–POA arrangement(s). Use the AMC sample and tailor it: responsibilities, data transfer cadence, deviations workflow, configuration/data ownership, and continued airworthiness support.
  • POE that people actually use. Treat POE + referenced procedures as the basic working docs (an explicit obligation). Keep it controlled and current.
  • Clean release logic. A short, visual decision tree for Form 1 vs. Declaration (standard parts; negligible safety-effect parts defined in ICA/CS-STAN; ELA cases) reduces errors at the line.
  • Configuration control by design family. Tie each part number to an unambiguous design baseline and effectivity, with clear change incorporation rules.
  • Supplier special process control. Pre-qualify, audit, and list approved sources for coatings, heat treat, NDT, etc., within your 21.A.139 PMS.
  • Right-sized internal audit & competence plan. Calibrate to your scope; audit for 21.A.139 effectiveness, not just paperwork.
  • Change discipline. Pre-agree with the authority what counts as significant PMS changes or location changes and obtain approvals under 21.A.147/148.

Quick decision guide for your new business – We want 21G but no 21J in-house. What’s our minimum viable path?

  1. Launch a standard parts line now (no Form 1 needed for installation eligibility; provide robust declarations).
  2. Secure one strong DOA–POA arrangement with a DAH for a first build-to-print package (so you can release on Form 1).
  3. If necessary for prototypes/low volume, request Subpart F as a time-boxed bridge while you finish your 21.A.139 PMS and POE for full 21G.
  4. Scale scope/Terms of Approval as competencies, audits, and supplier base mature.

Next Steps

Please see Sofema Aviation Services for Classroom or Webinar Training & Sofema Online for online training – for comments & questions please email [email protected]

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Subpart F, decision guide, Manage changes, Form 53, sourcing of design data, Supplier control, eligibility mistakes, satisfactory control, ETSO route, DOA. POA, Standard parts, 21J (DOA), 21G (POA), major change approvals, Best-practice blueprint, Part 21G, Part 21J