(7) hull or floats; (8) elements of an airframe including spars, ribs, fittings, shock absorbers, bracing,

        cowlings, fairings, and balance weights;

(9) hydraulic and electrical actuating system of components;

(10) rotor blades; (11) changes to the empty weight or empty balance which result in an increase in the

        maximum Certified weight or centre of gravity limits of the aircraft; (12) changes to the basic design of the fuel, oil, cooling, heating, cabin pressurisation, 

        electrical, hydraulic, de-icing, or exhaust systems; (13) changes to the wing or to fixed or movable control surfaces which affect flutter and 

        vibration characteristics;

(b) Power Plant Major Modifications. Major power plant modifications, even when not listed in the applicable engine specifications, include —

(1) conversion of an aircraft engine from one approved model to another, involving any changes in compression ratio, propeller reduction gear, impeller gear ratios or the substitution of major engine parts which requires extensive rework and testing of the engine;

(2) changes to the engine by replacing aircraft engine structural parts with parts not supplied by the original manufacturer or parts not specifically approved by the Authority;

(3) installation of an accessory which is not approved for the engine;

(4) removal of accessories that are listed as required equipment on the aircraft or engine specification;

(5) installation of structural parts other than the type of parts approved for the installation;

(6) conversions of any sort for the purpose of using fuel of a rating or grace other than that listed in the engine specifications.

(c) Propeller Major Modifications. Major propeller modifications, when not authorised in the applicable propeller specifications, include —

(1) changes in blade design;

(2) changes in hub design;

(3) changes in the governor or control design;

(4) installation of a propeller governor or feathering system;

(5) installation of propeller de-icing system;

(6) installation of parts not approved for the propeller.

 (d) Appliance Major Modifications. 

Modifications of the basic design not made in accordance with recommendations of the appliance manufacturer or in accordance with applicable Airworthiness Directive are appliance major modifications. In addition, changes in the basic design of radio communication and navigation equipment approved under type certification or other authorisation that have an effect on frequency stability, noise level, sensitivity, selectivity, distortion, spurious radiation, AVC characteristics, or ability to meet environmental test conditions and other changes that have an effect on the performance of the equipment are also major modifications.
APPENDIX 2 TO 5.005:  MAJOR REPAIRS (DEFINITION) (a) "Airframe Major Repairs" 

Repairs to the following parts of an airframe and repairs of the following types, involving the strengthening, reinforcing, splicing, and manufacturing of primary structural members of their replacement, when replacement is by fabrication such as riveting or welding, are airframe major repairs -

(1) box beams;

(2)   monocoque or semi-monocoque wings or control surfaces;

(3) wing stringers or chord members;

(4) spars;

(5) spar flanges;

(6) members of truss-type beams;

(7) thin sheet webs of beams;

(8) keel and chine members of boat hulls or floats;

(9)  corrugated sheet compression members which act as flange material of wings 

           or  tail surfaces;
　
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