SECTION 1
GENERAL
CESSNA
MODEL 172N
WEIGHT AND BALANCE TERMINOLOGY
Reference
Datum
Station
Arm
Moment
Center of
Gravity
(C.G.)
C.G.
Arm
C.G.
Limits
Standard
Empty
Weight
Basic Empty
Weight
Useful
Load
Maximum
Ramp
Weight
Maximum
Takeoff
Weight
1-8
Reference Datum
is an imaginary vertical plane from
which all horizontal distances are measured for balance
purposes.
Station
is a location along the airplane fuselage given in
terms of the distance from the reference datum.
Arm is the horizontal distance from the reference datum to
the center of gravity (C.G.) of an item.
Moment
is the product of the weight of an item multiplied
by its arm. (Moment divided by the constant 1000is used in
this handbook to simplify balance ca.lculations by reduc
ing the number of digits.)
Center of Gravity
is the point at which an airplane, or
equipment, would balance if suspended. Its distance from
the reference datum is found by dividing the total moment
by the total weight of the airplane.
Center of Gravity Arm
is the arm obtained by adding the
airplane's individual moments and dividing the sum by
the total weight.
Center of Gravity Limits
are the extreme center of gravity
locations within which the airplane must be operated at a
given weight.
Standard Empty Weight
is the weight of a standard air
plane, including unusable fuel, full operating fluids and
full engine oil.
Basic Empty Weight
is the standard empty weight plus the
weight of optional equipment.
Useful Load
is the difference between ramp weight and the
basic empty weight.
Maximum Ramp Weight
is the maximum weight approved
for ground maneuver. (It includes the weight of start, taxi,
and runup fuel.)
Maximum Takeoff Weight
is the maximum weight ap
proved for the start of the takeoff run.
1 July 1979