Manufacturers may also choose to group related systems where the simplicity of the product permits.

The flight compartment is the compartment above the floor and between the forward passenger partition and the forward pressure dome.

Inspection and observation are the windows used for examining compartments and equipment in and about the airplane, including items such as transparent material, its frame, etc.

Auxiliary structure includes leading edge, trailing edge, wing tip, tip fuel tank and fuel or water cell backing boards, not including plates/skin.

Attach fittings are the fittings on the wing used for the attachment of fuselage, nacelle/ pylon, and landing gear to the wing and for the support of equipment within the wing.

Flight surfaces are the structure of removable airfoils attached to the wing including items such as ailerons, flaps, spoilers, tabs, drag and balancing devices, etc.

Elevator/Elevon is the removable airfoil which is used for longitudinal/longitudinal and lateral control.

The horizontal airfoil of the tail/ nose section to which the elevator/ canard is attached includes items such as spars, ribs, stringers, plates/skin, access covers, tips, etc.

The horizontal and vertical stabilizers include the structure of the elevator and rudder.

Storage is that portion of the system used for storage of oil. It includes items such as tanks, filling systems, internal hoppers, baffles, tank sump and drain, etc.

Noise suppressor includes items such as pipes, baffles, shields, actuators, plumbing, linkages, position indicators, warning systems, etc.