Cirrus SR22 Pilot Operating Handbook page 23

C D
IRRUS ESIGN
SR22
Table 5: Weight and Balance Terminology
Terminology
Reference Datum Reference Datum is an imaginary vertical plane from
Tare
Fuselage Station
CG
Arm
Moment
Basic Empty
Weight
MAC
LEMAC
P/N 13772-006
Reissue A
Weight and Balance Terminology
which all horizontal distances are measured for
balance purposes.
Tare is the weight of all items used to hold or position
the airplane on the scales for weighing. Tare includes
blocks, shims, and chocks. Tare weight must be
subtracted from the associated scale reading.
Fuselage Station (FS) 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 FS 123.
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 (CG) of an item. The
airplane's arm is obtained by adding the airplane's
individual moments and dividing the sum by the total
weight.
Moment is the product of the weight of an item
multiplied by its arm.
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.
Mean Aerodynamic Chord is the chord drawn
through the centroid of the wing plan area.
Leading Edge of Mean Aerodynamic Chord is the
forward edge of MAC given in inches aft of the
reference datum (fuselage station).
S
ECTION
Definition
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