APPENDIX II CLASS AND RATING SYSTEM FOR THE TERMS OF APPROVAL OF PART-145 MAINTENANCE ORGANISATIONS

SI 2025 No. 1150

  1. Except as stated otherwise for the smallest organisations referred to in point (m), the table in point (l) provides the possible classes and ratings to be used to establish the terms of approval of the certificate of the organisation approved in accordance with Annex II (Part‑145). An organisation must be granted terms of approval that range from a single class and rating with limitations to all classes and ratings with limitations.

  2. In addition to the table in point (l), each maintenance organisation is required to indicate its scope of work in its MOE.

  3. Within the approval classes and ratings established by the CAA, the scope of work specified in the MOE defines the exact limits of its approval. It is therefore essential that the approval classes and ratings and the organisation’s scope of work match.

  4. A “category A class rating” means that the maintenance organisation may carry out maintenance on aircraft and components (including engines, auxiliary power units (APUs) or both), in accordance with the aircraft maintenance data or, if agreed by the CAA, in accordance with the component maintenance data, only while such components are fitted to the aircraft. Nevertheless, such an A‑rated maintenance organisation may temporarily remove a component for maintenance in order to improve access to that component, except when its removal generates the need for additional maintenance that the organisation is not approved to perform. Such removal of component for maintenance by A‑rated maintenance organisation must be subject to an appropriate control procedure in the MOE. The limitation column must specify the scope of such maintenance in order to indicate the extent of the approval.

  5. Category A class ratings are subdivided into “Base” or “Line” maintenance categories. Such an organisation may be approved for either “Base” or “Line” maintenance, or both. It should be noted that a “Line” facility located at a main base facility requires a “Line” maintenance approval.

  6. A “category B class rating” means that the maintenance organisation may carry out maintenance on uninstalled engines, APUs and engines, APU components or a combination of them, in accordance with the engine or APU maintenance data or both, or, if agreed by the CAA, in accordance with the component maintenance data, only while such components are fitted to the engine, the APU or both. Nevertheless, such a B‑rated approved maintenance organisation may temporarily remove a component for maintenance in order to improve access to that component, except when its removal generates the need for additional maintenance that the organisation is not approved to perform. The limitation column must specify the scope of such maintenance, thereby indicating the extent of the approval. A maintenance organisation that is approved with a category B class rating may also carry out maintenance on an installed engine during aircraft base and line maintenance, provided that an appropriate control procedure in the MOE has been approved by the CAA. The scope of work in the MOE must reflect those activities if they are permitted by the CAA.

  7. A “category C class rating” means that the maintenance organisation may carry out maintenance on uninstalled components (excluding complete engines and APUs) that are intended to be fitted on the aircraft or the engine or APU. The limitation column must specify the scope of such maintenance, thereby indicating the extent of the approval. A maintenance organisation that is approved with a category C class rating may also carry out maintenance on an installed component (other than a complete engine or APU) during aircraft base and line maintenance, or at an engine or APU maintenance facility provided that an appropriate control procedure in the MOE has been approved by the CAA. The scope of work in the MOE must reflect those activities if they are permitted by the CAA.

  8. A “category D class rating” means a self‑contained class rating that is not necessarily related to a specific aircraft, engine or other component. The D1 – Non-Destructive Testing (“NDT”) rating is only necessary for a maintenance organisation that carries out NDT as a particular task for another organisation. A maintenance organisation that is approved with a class rating in the A, B or C category may carry out NDT on products that it maintains without the need for a D1 class rating provided that the MOE contains appropriate NDT procedures.

  9. The limitation column is intended to give the CAA the flexibility to customise an approval for any particular organisation. Ratings may only be mentioned on the approval if they are appropriately limited. The table in point (l) specifies the types of limitations that are possible. It is acceptable to stress in the limitation column the maintenance task rather than the type or manufacturer of the aircraft or engine, if that is more appropriate to the organisation (an example could be avionics systems installations and the related maintenance). If that is mentioned in the limitation column, it indicates that the maintenance organisation is approved to carry out maintenance up to and including that particular type or task.

  10. When reference is made to the series, type and group in the limitation column of class A and B, it must be understood as follows:

    “series” means a specific type series such as the Airbus 300, 310, 319, the Boeing 737-300 series, RB211-524 series, Cessna 150, Cessna 172, Beech 55 series or the Continental O-200 series;

    “type” means a specific type or model such as the Airbus 310‑240 type, the RB 211‑524 B4 type, or the Cessna 172RG type. Any number of series or types may be quoted;

    “group” means, for example, Cessna single piston engine aircraft or Lycoming non‑supercharged piston engines, etc.

  11. By way of derogation from point 145.A.85(a)(1), where a component capability list is used that could be subject to frequent amendments, then the organisation may propose to include such amendments in the procedure referred to in point 145.A.85(c) for changes not requiring prior approval.

  12. Limitation

    CLASS RATING LIMITATION BASE LINE
    AIRCRAFT

    A1

    Aeroplanes above 5,700kg maximum take- off mass (MTOM)

    		[Must state the aeroplane manufacturer or the group or series or type and/or the maintenance tasks] Example: Airbus A320 Series [YES/NO](*) [YES/NO](*)
     

    A2

    Aeroplanes of 5,700kg MTOM and below

    		 [Must state the aeroplane manufacturer or the group or series or type and/or the maintenance tasks] Example: DHC-6 Twin Otter Series State whether the issuing of airworthiness review certificates is authorised (only possible for aircraft covered by Annex 5b (Part-ML)) [YES/NO](*) [YES/NO](*)
     

    A3

    Helicopters

    		[Must state the helicopter manufacturer or the group or series or type and/or the maintenance task(s)] Example: Robinson R44 State whether the issuing of airworthiness review certificates is authorised (only possible for aircraft covered by Annex 5b (Part-ML)) [YES/NO](*) [YES/NO](*)
     

    A4

    Aircraft other than A1, A2 and A3 aircraft

    		[Must state the aircraft category (sailplane, balloon, airship, etc.), the manufacturer or group or series or type and/or the maintenance task(s)] State whether the issuing of airworthiness review certificates is authorised (only possible for aircraft covered by Annex 5b (Part-ML)) [YES/NO](*) [YES/NO](*)
    ENGINES

    B1

    Turbine

    [Must state the engine series or type and/or the maintenance task(s)]

    Example: PT6A Series

     

    B2

    Piston

    		 [Must state the engine manufacturer or group or series or type and/or the maintenance task(s)]
     

    B3

    APU

    		[Must state the engine manufacturer or series or type and/or the maintenance task(s)]
    COMPONENTS OTHER THAN COMPLETE ENGINES OR APUs

    C1

    Air Cond & Press

    [Must state the aircraft type or aircraft manufacturer or component manufacturer or the particular component and/or cross-refer to a capability list in the exposition and/or the maintenance task(s)] Example: PT6A Fuel Control

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     
      C2 Auto Flight
      C3 Comms and Nav
      C4 Doors — Hatches
      C5 Electrical Power & Lights
      C6 Equipment
      C7 Engine – APU
      C8 Flight Controls
      C9 Fuel
      C10 Helicopter – Rotors
      C11 Helicopter – Trans
      C12 Hydraulic Power
      C13 Indicating – recording system
      C14 Landing Gear
      C15 Oxygen
      C16 Propellers
      C17 Pneumatic & Vacuum
      C18 Protection ice/rain/fire
      C19 Windows
      C20 Structural
      C21 Water ballast
      C22 Propulsion Augmentation
    SPECIALISED SERVICES D1 Non-Destructive Testing [Must state particular NDT method(s)]

    (*) Delete as appropriate.

  13. A maintenance organisation which employs only one person to both plan and carry out all maintenance activities can only hold limited terms of approval. The maximum permissible limits are as follows.

    Class Rating Limitation
    Aircraft A2 Piston engine aeroplane of 5,700 kg MOTM or less Single piston engine helicopter of 3,175 kg MTOM or less
    Aircraft A3
    Aircraft A4 No limitations
    Engines B2 Less than 450HP
    Components other than complete engines or APUs C1 to C22 As per capability list
    Specialised Services D1 NDT NDT method(s) to be specified

  14. It should be noted that such an organisation may be further limited by the competent authority in the terms of approval depending on the capabilities of the particular organisation.