DENSITY ALTITUDE
MIXTURE
FULL RICH
OAT 120°F
OAT 100°F
OAT 80°F
OAT 60°F
OAT 40°F
OAT 20°F
OAT 0°F
Figure 6-7. One of the performance charts in the Performance
Section is the “In Ground Effect Hover Ceiling versus Gross
Weight” chart. This chart allows you to determine how much
weight you can carry and still operate at a specific pressure
altitude, or if you are carrying a specific weight, what is your
altitude limitation.
7-1
It is vital to comply with weight and balance limits
established for helicopters. Operating above the maximum
weight limitation compromises the structural
integrity of the helicopter and adversely affects performance.
Balance is also critical because on some
fully loaded helicopters, center of gravity deviations as
small as three inches can dramatically change a helicopter’s
handling characteristics. Taking off in a helicopter
that is not within the weight and balance
limitations is unsafe.
WEIGHT
When determining if your helicopter is within the
weight limits, you must consider the weight of the basic
helicopter, crew, passengers, cargo, and fuel. Although
the effective weight (load factor) varies during maneuvering
flight, this chapter primarily considers the
weight of the loaded helicopter while at rest.
The following terms are used when computing a helicopter’s
weight.
BASIC EMPTY WEIGHT—The starting point for
weight computations is the basic empty weight, which
is the weight of the standard helicopter, optional
equipment, unusable fuel, and full operating fluids
including full engine oil. Some helicopters might use
the term “licensed empty weight,” which is nearly the
same as basic empty weight, except that it does not
include full engine oil, just undrainable oil. If you fly a
helicopter that lists a licensed empty weight, be sure to
add the weight of the oil to your computations.
USEFUL LOAD—The difference between the gross
weight and the basic empty weight is referred to as
useful load. It includes the flight crew, usable fuel,
drainable oil, if applicable, and payload.
PAYLOAD—The weight of the passengers, cargo, and
baggage.
GROSS WEIGHT—The sum of the basic empty weight
and useful load.
MAXIMUM GROSS WEIGHT— The maximum
weight of the helicopter. Most helicopters have an internal
maximum gross weight, which refers to the weight
within the helicopter structure and an external maximum
gross weight, which refers to the weight of the helicopter
with an external load.
WEIGHT LIMITATIONS
Weight limitations are necessary to guarantee the structural
integrity of the helicopter, as well as enabling you
to predict helicopter performance accurately. Although
aircraft manufacturers build in safety factors, you
should never intentionally exceed the load limits for
which a helicopter is certificated. Operating above a
maximum weight could result in structural deformation
or failure during flight if you encounter excessive load
factors, strong wind gusts, or turbulence. Operating
below a minimum weight could adversely affect the
handling characteristics of the helicopter. During single-
pilot operations in some helicopters, you may have
to use a large amount of forward cyclic in order to
maintain a hover. By adding ballast to the helicopter,
the cyclic will be closer to the center, which gives you
a greater range of control motion in every direction.
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