Piper CHEROKEE WARRIOR II, Pilot Operating Handbook, Page: 22 / 282

(f) Weight and Balance Terminology
Reference Datum An imaginary vertical plane from which all horizontal distances are
measured for balance purposes.
Station A location along the airplane fuselage usually given in terms of
distance from the reference datum.
Arm The horizontal distance from the reference datum to the center of
gravity (C.G.) of an item.
Moment The product of the weight of an item multiplied by its arm.
(Moment divided by a constant is used to simplify balance
calculations by reducing the number of digits.)
Center of Gravity The point at which an airplane would balance if suspended. Its
(C.G.) distance from the reference datum is found by dividing the total
moment by the total weight of the airplane.
C.G. Arm The arm obtained by adding the airplane’s individual moments and
dividing the sum by the total weight.
C.G. Limits The extreme center of gravity locations within which the airplane
must be operated at a given weight.
Usable Fuel Fuel available for flight planning.
Unusable Fuel Fuel remaining after a runout test has been completed in
accordance with governmental regulations.
Standard Empty Weight Weight of a standard airplane including unusable fuel, full
operating fluids and full oil.
Basic Empty Weight Standard empty weight plus optional equipment.
Payload Weight of occupants, cargo and baggage.
Useful Load Difference between takeoff weight, or ramp weight if applicable,
and basic empty weight.
Maximum Ramp Weight Maximum weight approved for ground maneuver. (It includes
weight of start, taxi and run up fuel.)
Maximum Takeoff Maximum weight approved for the start of the takeoff run.
Weight
Maximum Landing Maximum weight approved for the landing touchdown.
Weight
Maximum Zero Fuel Maximum weight exclusive of usable fuel.
Weight
REPORT: VB-880 ISSUED: DECEMBER 16, 1976
1-8
SECTION 1 PIPER AIRCRAFT CORPORATION
GENERAL PA-28-161, CHEROKEE WARRIOR II