--- title: "21.A.112B Demonstration of capability — Annex I, Initial Airworthiness · Avioverse" description: "An applicant for a supplemental type-certificate shall demonstrate its capability by holding a design organisation approval, issued by the Agency in…" url: "https://avioverse.aero/regulations/easa/initial-airworthiness/annex-i/section-a-technical-requirements/21-a-112b" --- # 21.A.112B Demonstration of capability Annex I · Regulation (EU) No 748/2012 · EAR revision 27 Nov 2025 IR Implementing rule ## 21.A.112B Demonstration of capability (a) An applicant for a supplemental type-certificate shall demonstrate its capability by holding a design organisation approval, issued by the Agency in accordance with Subpart J. (b) By way of derogation from point (a), as an alternative procedure to demonstrate its capability, an applicant may seek Agency agreement for the use of procedures setting out the specific design practices, resources and sequence of activities necessary to comply with this Subpart. (c) By way of derogation from point (a), in the case of products referred to in point 21.A.14(c), an applicant may demonstrate its capability by obtaining the Agency's acceptance of its certification programme established in accordance with point 21.A.93(b). IR · 21.A.112B — Regulation (EU) No 748/2012 · Regulation (EU) 2019/897 · Initial Airworthiness Easy Access Rules · EAR revision 27 Nov 2025 GM Guidance material ## GM1 21.A.112B Demonstration of capability DEMONSTRATION OF CAPABILITY FOR SUPPLEMENTAL TYPE CERTIFICATE (STC) CASES See also AMC 21.A.14(b) for the details of the alternative procedures. The following examples of major changes to type design (ref.: 21.A.91) are classified in two groups. Group 1 contains cases where a design organisation approved under [Part 21](https://avioverse.aero/glossary/easa/part-21) Subpart J (‘Subpart J DOA’) should be required, and Group 2 cases where the alternative procedure may be accepted. They are typical examples but each STC case should be addressed on its merits and there would be exceptions in practice. This classification is valid for new STCs, not for evolution of STCs, and may depend upon the nature of the STC (complete design or installation). | Product | Discipline | Kind of STC | | Group | | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | --------------- | --------------------------------------------------------------------------------------------------- | - | ----- | | All aircraft | | | | | | | OSD | | | | | | | Major stand-alone change to any OSD constituent | | 1 | | | | | | | | Products for which an alternative procedure may be accepted according to 21.A.14(b) | All disciplines | | 2 | | | | | | | | | CS-23 (products where a Subpart J DOA is required for TC) | | | | | | Notes: 1) An STC which leads to a reassessment of the loads on large parts of the primary structure should be in Group 1. 2) ‘2/1’ means that an assessment of consequences in terms of handling qualities, performance or complexity of demonstration of compliance may lead to classification in Group 1. | | | | | | | Aircraft | | | | | | | Conversion to tail wheel configuration | | 1 | | | | Auxiliary fuel tank installations | | 2/1 | | | | Glass fibre wing tips | | 2/1 | | | | Fairings: nacelle, landing gear | | 2 | | | | Gap seals: aileron, flap, empennage, doors | | 2 | | | | Vortex generators | | 2/1 | | | | Spoiler installation | | 1 | | | | Increase in MTOW | | 1 | | | Structures | | | | | | | Stretcher installation | | 2 | | | | Change to seating configuration | | 2 | | | | Windshield replacement (heated, single piece, etc.) | | 2 | | | | Lightweight floor panels | | 2 | | | | Ski installations | | 2/1 | | | Propulsion | | | | | | | Engine model change | | 1 | | | | Fixed pitch propeller installation | | 2 | | | | Constant speed propeller installation | | 2/1 | | | | Installation of exhaust silencer | | 2 | | | | Installation of graphic engine monitor | | 2 | | | | Installation of fuel flow meter | | 2 | | | | Accessory replacement (alternator, magnetos, etc.) | | 2 | | | | Inlet modifications: oil cooler; induction air | | 2 | | | Equipment | | | | | | | Avionics upgrades (EFIS, GPS, etc.) | | 2/1 | | | | Engine instrument replacements | | 2 | | | | Carburettor ice detection system | | 2 | | | | Autopilot system installation | | 1 | | | | Wing tip landing light; recognition lights | | 2 | | | | WX radar installation | | 2 | | | | Aeromedical system installations | | 2 | | | | De-icing and anti-icing system installations | | 1 | | | | Emergency power supply installations | | 2 | | CS-25 | | | | | | | Cabin Safety | | | | | Note: Basically, all changes related to cabin configuration should be in Group 2. | | Cabin layout (installation of seats (16G), galleys, single class or business / economy class, etc.) | | 2 | | | | Floor path marking | | 2 | | | | Crew rest compartment | | 1 | | | | Change of cargo compartment classification (from class D to class C) | | 1 | | | Structure | | | | | Note: An STC which leads to a reassessment of the loads on large parts of the primary structure should be in Group 1. | | Cargo door | | 1 | | | | Change from passenger to freighter configuration | | 1 | | | Avionics | | | | | Notes: For CS-25 products, the existence of an [ETSO](https://avioverse.aero/glossary/easa/etso) is not taken into account for the classification. The impact on aircraft performance, and influence of aircraft performance are criteria to assess the classification. Subjective assessment of human factors is considered for determination of the classification. | | CVR | | 2 | | | | VHF | | 2 | | | | NAV (ADF, VOR, GPS, BRNAV) | | 2 | | | | Autopilot, HUD, EFIS, FMS | | 1 | | | | DFDR | | 2/1 | | | | Meteo radar | | 2 | | | | ILS Cat 3 | | 1 | | | | RVSM | | 1 | | | | TCAS, EGPWS | | 1 | | | | GPWS | | 2 | | | Powerplant | | | | | | | Auxiliary fuel tanks | | 1 | | | | Thrust reverser system | | 1 | | | | Hushkit | | 1 | | | | Fire detection | | 1 | | | | Fuel gauging | | 1 | | | | Change of engine or propeller | | 1 | | CS-27 or CS-29 | All disciplines | | | | | Note: 2/1 means that an assessment of consequences in terms of handling qualities and performance may lead to classification in Group 1. | | Replacement of main rotor or tail rotor blades | | 1 | | | | Autopilot | | 1 | | | | Engine type change | | 1 | | | | GPS installation | | 2 | | | | Jettisonable overhead raft installation | | 2 | | | | Utility basket installation | | 2/1 | | | | Nose or side mount camera installation | | 2/1 | | | | Passenger access step installation | | 2/1 | | | | Protection net & handle installation (parachuting) | | 2 | | | | VIP cabin layout | | 2 | | | | Navigation system installation | | 2 | | | | Fuel boost pump automatic switch-on installation | | 2 | | | | Decrease of maximum seating capacity | | 2 | | | | Agricultural spray kit installation | | 2/1 | | | | Long exhaust pipe installation | | 2 | | | | Flotation gear installation | | 2/1 | | | | Wipers installation | | 2 | | | | Engine oil filter installation | | 2 | | | | Skid gear covering installation | | 2/1 | | | | Gutter installation (top pilot door) | | 2 | | | | Cable cutter installation | | 2 | | | | Auxiliary fuel tank fixed parts installation | | 2 | | | | Cabin doors windows replacement | | 2 | | | | Radio altimeter aural warning installation | | 2 | | | | Standby horizon autonomous power supply | | 2 | | | | Fire attack system | | 2/1 | | | | Hoisting system installation | | 2/1 | | | | External loads hook installation | | 2 | | | | Emergency flotation gear installation | | 2/1 | | | | Heating/demisting (P2 supply) | | 2 | GM · GM1 21.A.112B — Regulation (EU) No 748/2012 · ED Decision 2021/001/R · Initial Airworthiness Easy Access Rules · EAR revision 27 Nov 2025 [All rules in SECTION A — TECHNICAL REQUIREMENTS](https://avioverse.aero/regulations/easa/initial-airworthiness/annex-i/section-a-technical-requirements) Consolidated from the EASA Easy Access Rules (revision 27 Nov 2025, extracted 13 Oct 2026) for convenience. Not the official publication — verify against the Official Journal of the European Union and the EASA publications before operational use.