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purpose of a zero fuel weight is to limit load forces on
the wing spars with heavy fuselage loads.
Assume a hypothetical multiengine airplane with the
following weights and capacities:
Basic empty weight . . . . . . . . . . . . . . . . .3,200 lb.
Zero fuel weight . . . . . . . . . . . . . . . . . . . .4,400 lb.
Maximum takeoff weight . . . . . . . . . . . . .5,200 lb.
Maximum usable fuel . . . . . . . . . . . . . . . .180 gal.
1. Calculate the useful load:
Maximum takeoff weight . . . . . . . . . . . . .5,200 lb.
Basic empty weight . . . . . . . . . . . . . . . . .-3,200 lb.
Useful load . . . . . . . . . . . . . . . . . . . . . . . .2,000 lb.
The useful load is the maximum combination of usable
fuel, passengers, baggage, and cargo that the airplane
is capable of carrying.
2. Calculate the payload:
Zero fuel weight . . . . . . . . . . . . . . . . . . . . 4,400 lb.
Basic empty weight . . . . . . . . . . . . . . . . . -3,200 lb.
Payload . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,200 lb.
The payload is the maximum combination of passengers,
baggage, and cargo that the airplane is capable
of carrying. A zero fuel weight, if published, is the
limiting weight.
3. Calculate the fuel capacity at maximum payload
(1,200 lb.):
Maximum takeoff weight . . . . . . . . . . . . .5,200 lb.
Zero fuel weight . . . . . . . . . . . . . . . . . . .-4,400 lb.
Fuel allowed . . . . . . . . . . . . . . . . . . . . . . . .800 lb.
Assuming maximum payload, the only weight permitted
in excess of the zero fuel weight must consist of
usable fuel. In this case, 133.3 gallons.
4. Calculate the payload at maximum fuel capacity
(180 gal.):
Basic empty weight . . . . . . . . . . . . . . . . .3,200 lb.
Maximum usable fuel . . . . . . . . . . . . . . .+1,080 lb.
Weight with max. fuel . . . . . . . . . . . . . . .4,280 lb.
Maximum takeoff weight . . . . . . . . . . . . .5,200 lb.
Weight with max. fuel . . . . . . . . . . . . . . .-4,280 lb.
Payload allowed . . . . . . . . . . . . . . . . . . . . .920 lb.
Assuming maximum fuel, the payload is the difference
between the weight of the fueled airplane and the maximum
takeoff weight.
Some multiengine airplanes have a ramp weight,
which is in excess of the maximum takeoff weight. The
ramp weight is an allowance for fuel that would be
burned during taxi and runup, permitting a takeoff at
full maximum takeoff weight. The airplane must
weigh no more than maximum takeoff weight at the
beginning of the takeoff roll.
A maximum landing weight is a limitation against
landing at a weight in excess of the published value.
This requires preflight planning of fuel burn to ensure
that the airplane weight upon arrival at destination will
be at or below the maximum landing weight. In the
event of an emergency requiring an immediate landing,
the pilot should recognize that the structural
margins designed into the airplane are not fully
available when over landing weight. An overweight
landing inspection may be advisable—the service
manual or manufacturer should be consulted.
12-11
Ch 12.qxd 5/7/04 9:54 AM Page 12-11
Although the foregoing problems only dealt with
weight, the balance portion of weight and balance
is equally vital. The flight characteristics of the
multiengine airplane will vary significantly with
shifts of the center of gravity (CG) within the
approved envelope.
At forward CGs, the airplane will be more stable, with
a slightly higher stalling speed, a slightly slower
cruising speed, and favorable stall characteristics.
At aft CGs, the airplane will be less stable, with a
slightly lower stalling speed, a slightly faster cruising
speed, and less desirable stall characteristics. Forward
CG limits are usually determined in certification by
elevator/stabilator authority in the landing roundout.
Aft CG limits are determined by the minimum
acceptable longitudinal stability. It is contrary to the
airplane’s operating limitations and the Code of
Federal Regulations (CFR) to exceed any weight
and balance parameter.
Some multiengine airplanes may require ballast to
remain within CG limits under certain loading conditions.
Several models require ballast in the aft baggage
compartment with only a student and instructor on
board to avoid exceeding the forward CG limit.
When passengers are seated in the aft-most seats of
some models, ballast or baggage may be required in
the nose baggage compartment to avoid exceeding
the aft CG limit. The pilot must direct the seating of
passengers and placement of baggage and cargo to
　
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