PRINCIPLES OF WEIGHT AND BALANCE
Section I. WEIGHT
2-1. General. Weight is one of the most important
factors to be considered from the time the aircraft is
designed until it is removed from service. It is of prime
importance to the manufacturer through all phases of
production and must remain foremost in the pilot's mind
when planning and carrying out missions. Changes in
the basic aircraft design weight, either in initial
production by the manufacturer, or in subsequent
modifications by maintenance activities, will have to
direct bearing on aircraft performance. Cargo/troop
loading and the aircraft gross weight should be
examined closely by the pilot as these factors may
determine the safety and success of a mission. Gross
weight limitations have been established and are in the
applicable -10 operator's manual for individual aircraft to
insure successful and efficient tactical operation.
2-2. Weight Definitions. Definitions of the more
important terms pertaining to weight and its relationship
to aircraft configurations and equipment are as follows:
a. Empty Weight. Empty weight includes the
weight of the aircraft structure plus power plant,
instrument systems, control systems, hydraulic systems,
electrical systems, communication systems, armament
provisions, furnishings, anti-icing equipment, auxiliary
power plant, anchor and towing provisions, and flotation
landing gear. This term is used for design purposes and
usually does not affect service activities.
b. Basic Weight. Basic weight of an aircraft is
that weight which includes all hydraulic systems and oil
systems full, trapped and unusable fuel, and all fixed
equipment, to which it is only necessary to add the crew,
fuel, cargo, and ammunition (if carried) to determine the
gross weight for the aircraft. The basic weight varies
with structural modifications and changes of fixed
c. Operating Weight. Operating weight includes
the basic weight plus aircrew, the aircrew's baggage,
equipment that may be required. Operating weight does
not include the weight of fuel, ammunition, bombs,
cargo, or external auxiliary fuel tanks if such tanks are
to be disposed of during flight.
d. Gross Weight. Gross weight is the total weight
of an aircraft and its contents.
e. Takeoff Gross Weight. Takeoff gross weight
ammunition, bombs, auxiliary fuel tanks, etc.
f. Landing Gross Weight. Landing gross weight
is the takeoff gross weight minus items expended during
g. Useful Load. Useful load is the difference
between empty weight and gross weight and includes
fuel, oil, crew, passengers, cargo, and other material
h. Service Weight Pickup. Service weight pickup
is the weight, accounted for and unaccounted for, which
is picked up by an aircraft during its service life.
Service weight pickup is due to repairs, modifications
(known pickup). Known pickup covers the actual parts
installed during repair, overhaul, and modification.
These parts should be weighed or, if weighing is
impractical, the weight must be calculated. Unknown
pickup results from changes in temperature and
humidity, moisture absorption by sound proofing,
accumulation of dirt, grease, etc., and can only be
determined by periodic and accurate weighing of the
i. Total Aircraft Weight. The sum of operating
weight, weight of take off fuel and weight of water
injection fluid, if applicable.
2-3. Weight Versus Aircraft Performance. An aircraft
is designed for specific weight limitations which cannot
be exceeded without compromising safety. Overloading
an aircraft may cause structural failure or result in
reduced engine and airframe life. An increase in gross
weight will have the following effects on aircraft
a. Increase takeoff distance.
b. Reduce hover performance.
Change 5 2-1