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Additional weight also improves autorotational characteristics
since the autorotational descent can be established
sooner. In addition, operating below minimum
weight could prevent you from achieving the desirable
rotor r.p.m. during autorotations.
Although a helicopter is certificated for a specified
maximum gross weight, it is not safe to take off with
this load under all conditions. Anything that adversely
affects takeoff, climb, hovering, and landing performance
may require off-loading of fuel, passengers, or
baggage to some weight less than the published maximum.
Factors which can affect performance include
high altitude, high temperature, and high humidity conditions,
which result in a high density altitude.
DETERMINING EMPTY WEIGHT
A helicopter’s weight and balance records contain
essential data, including a complete list of all installed
optional equipment. Use these records to determine the
weight and balance condition of the empty helicopter.
When a helicopter is delivered from the factory, the basic
empty weight, empty weight center of gravity (CG), and
useful load are recorded on a weight and balance data
sheet included in the FAA-Approved Rotocraft Flight
Manual. The basic empty weight can vary even in the
same model of helicopter because of differences in
installed equipment. If the owner or operator of a helicopter
has equipment removed, replaced, or additional
equipment installed, these changes must be reflected in
the weight and balance records. In addition, major
7-2
repairs or alterations must be recorded by a certified
mechanic. When the revised weight and moment are
recorded on a new form, the old record is marked with
the word “superseded” and dated with the effective
date of the new record. This makes it easy to determine
which weight and balance form is the latest version.
You must use the latest weight and balance data for
computing all loading problems.
BALANCE
Helicopter performance is not only affected by gross
weight, but also by the position of that weight. It is
essential to load the aircraft within the allowable centerof-
gravity range specified in the rotorcraft flight manual’s
weight and balance limitations.
CENTER OF GRAVITY (CG)
The center of gravity is defined as the theoretical point
where all of the aircraft’s weight is considered to be
concentrated. If a helicopter was suspended by a cable
attached to the center-of-gravity point, it would balance
like a teeter-totter. For helicopters with a single main
rotor, the CG is usually close to the main rotor mast.
Improper balance of a helicopter’s load can result in
serious control problems. The allowable range in which
the CG may fall is called the “CG range.” The exact
CG location and range are specified in the rotorcraft
flight manual for each helicopter. In addition to making
a helicopter difficult to control, an out-of-balance loading
condition also decreases maneuverability since
cyclic control is less effective in the direction opposite
to the CG location.
Ideally, you should try to perfectly balance a helicopter
so that the fuselage remains horizontal in hovering
flight, with no cyclic pitch control needed except for
wind correction. Since the fuselage acts as a pendulum
suspended from the rotor, changing the center of gravity
changes the angle at which the aircraft hangs from
the rotor. When the center of gravity is directly under
the rotor mast, the helicopter hangs horizontal; if the
CG is too far forward of the mast, the helicopter hangs
with its nose tilted down; if the CG is too far aft of the
mast, the nose tilts up. [Figure 7-1]
CG FORWARD OF FORWARD LIMIT
A forward CG may occur when a heavy pilot and passenger
take off without baggage or proper ballast
located aft of the rotor mast. This situation becomes
worse if the fuel tanks are located aft of the rotor mast
because as fuel burns the weight located aft of the rotor
mast becomes less.
You can recognize this condition when coming to a
hover following a vertical takeoff. The helicopter will
have a nose-low attitude, and you will need excessive
rearward displacement of the cyclic control to maintain
a hover in a no-wind condition. You should not continue
flight in this condition, since you could rapidly run out
of rearward cyclic control as you consume fuel. You also
may find it impossible to decelerate sufficiently to bring
the helicopter to a stop. In the event of engine failure and
the resulting autorotation, you may not have enough
　
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