CIRRUS DESIGN SR20, Pilot Operating Handbook

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P/N 11934-003 1-11
Cirrus Design Section 1
SR20 General
Weight and Balance Terminology
• Unusable Fuel is the quantity of fuel that cannot be safely
used in flight.
• Usable Fuel is the fuel available for flight planning.
c.g. Center of Gravity is the point at which an airplane would
balance if suspended. Its distance from the reference datum
is found by dividing the total moment by the total weight of
the airplane.
• Arm is the horizontal distance from the reference datum to
the center of gravity (c.g.) of an item. The airplane’s arm is
obtained by adding the airplane’s individual moments and
dividing the sum by the total weight.
• Basic Empty Weight is the actual weight of the airplane
including all operating equipment that has a fixed location in
the airplane. The basic empty weight includes the weight of
unusable fuel and full oil.
MAC Mean Aerodynamic Chord is the chord drawn through the
centroid of the wing plan area.
LEMAC Leading Edge of Mean Aerodynamic Chord is the forward
edge of MAC given in inches aft of the reference datum
(fuselage station).
• Maximum Gross Weight is the maximum permissible
weight of the airplane and its contents as listed in the aircraft
specifications.
• Moment is the product of the weight of an item multiplied by
its arm.
• Useful Load is the basic empty weight subtracted from the
maximum weight of the aircraft. It is the maximum allowable
combined weight of pilot, passengers, fuel and baggage.
• Station is a location along the airplane fuselage measured
in inches from the reference datum and expressed as a
number. For example: A point 123 inches aft of the
reference datum is Fuselage Station 123.0 (FS 123).
Reissue A