There are many factors that lead to efficient and safe
operation of aircraft. Among these vital factors is proper
weight and balance control. The weight and balance
system commonly employed among aircraft consists of
three equally important elements: the weighing of the
aircraft, the maintaining of the weight and balance records,
and the proper loading of the aircraft. An inaccuracy in any
one of these elements nullifies the purpose of the whole
system. The final loading calculations will be meaningless
if either the aircraft has been improperly weighed or the
records contain an error.
Improper loading cuts down the efficiency of an aircraft
from the standpoint of altitude, maneuverability, rate
of climb, and speed. It may even be the cause of failure
to complete the flight, or for that matter, failure to start
the flight. Because of abnormal stresses placed upon the
structure of an improperly loaded aircraft, or because of
changed flying characteristics of the aircraft, loss of life
and destruction of valuable equipment may result.
The responsibility for proper weight and balance control
begins with the engineers and designers, and extends to the
aircraft mechanics that maintain the aircraft and the pilots
who operate them.
Modern aircraft are engineered utilizing state-of-the-art
technology and materials to achieve maximum reliability
and performance for the intended category. As much
care and expertise must be exercised in operating and
maintaining these efficient aircraft as was taken in their
design and manufacturing.
The designers of an aircraft have set the maximum weight,
based on the amount of lift the wings or rotors can provide
under the operation conditions for which the aircraft
is designed. The structural strength of the aircraft also
limits the maximum weight the aircraft can safely carry.
The ideal location of the center of gravity (CG) was very
carefully determined by the designers, and the maximum
deviation allowed from this specific location has been
calculated.
The manufacturer provides the aircraft operator with the
empty weight of the aircraft and the location of its emptyweight
center of gravity (EWCG) at the time the certified
aircraft leaves the factory. Amateur-built aircraft must have
this information determined and available at the time of
certification.
The airframe and powerplant (A&P) mechanic or
repairman who maintains the aircraft keeps the weight and
balance records current, recording any changes that have
been made because of repairs or alterations.
The pilot in command of the aircraft has the responsibility
on every flight to know the maximum allowable weight
of the aircraft and its CG limits. This allows the pilot to
determine on the preflight inspection that the aircraft is
loaded in such a way that the CG is within the allowable
limits.
Weight is a major factor in airplane construction and
operation, and it demands respect from all pilots and
particular diligence by all A&P mechanics and repairmen.
Excessive weight reduces the efficiency of an aircraft
and the safety margin available if an emergency
condition should arise.
When an aircraft is designed, it is made as light as the
required structural strength will allow, and the wings or
rotors are designed to support the maximum allowable
weight. When the weight of an aircraft is increased,
the wings or rotors must produce additional lift and the
structure must support not only the additional static loads,
but also the dynamic loads imposed by flight maneuvers.
For example, the wings of a 3,000-pound airplane must
support 3,000 pounds in level flight, but when the airplane
is turned smoothly and sharply using a bank angle of 60°,
the dynamic load requires the wings to support twice this,
or 6,000 pounds.
Severe uncoordinated maneuvers or flight into turbulence
can impose dynamic loads on the structure great enough
1–
to cause failure. In accordance with Title 14 of the Code
of Federal Regulations (14 CFR) part 23, the structure of a
normal category airplane must be strong enough to sustain
a load factor of 3.8 times its weight. That is, every pound
of weight added to an aircraft requires that the structure
be strong enough to support an additional 3.8 pounds.
An aircraft operated in the utility category must sustain a
load factor of 4.4, and acrobatic category aircraft must be
strong enough to withstand 6.0 times their weight.
The lift produced by a wing is determined by its airfoil
shape, angle of attack, speed through the air, and the air
density. When an aircraft takes off from an airport with a
high density altitude, it must accelerate to a speed faster
than would be required at sea level to produce enough
lift to allow takeoff; therefore, a longer takeoff run is
necessary. The distance needed may be longer than the
available runway. When operating from a high-density
altitude airport, the Pilot’s Operating Handbook (POH)
or Airplane Flight Manual (AFM) must be consulted to
determine the maximum weight allowed for the aircraft
under the conditions of altitude, temperature, wind, and
runway conditions.
operation of aircraft. Among these vital factors is proper
weight and balance control. The weight and balance
system commonly employed among aircraft consists of
three equally important elements: the weighing of the
aircraft, the maintaining of the weight and balance records,
and the proper loading of the aircraft. An inaccuracy in any
one of these elements nullifies the purpose of the whole
system. The final loading calculations will be meaningless
if either the aircraft has been improperly weighed or the
records contain an error.
Improper loading cuts down the efficiency of an aircraft
from the standpoint of altitude, maneuverability, rate
of climb, and speed. It may even be the cause of failure
to complete the flight, or for that matter, failure to start
the flight. Because of abnormal stresses placed upon the
structure of an improperly loaded aircraft, or because of
changed flying characteristics of the aircraft, loss of life
and destruction of valuable equipment may result.
The responsibility for proper weight and balance control
begins with the engineers and designers, and extends to the
aircraft mechanics that maintain the aircraft and the pilots
who operate them.
Modern aircraft are engineered utilizing state-of-the-art
technology and materials to achieve maximum reliability
and performance for the intended category. As much
care and expertise must be exercised in operating and
maintaining these efficient aircraft as was taken in their
design and manufacturing.
The designers of an aircraft have set the maximum weight,
based on the amount of lift the wings or rotors can provide
under the operation conditions for which the aircraft
is designed. The structural strength of the aircraft also
limits the maximum weight the aircraft can safely carry.
The ideal location of the center of gravity (CG) was very
carefully determined by the designers, and the maximum
deviation allowed from this specific location has been
calculated.
The manufacturer provides the aircraft operator with the
empty weight of the aircraft and the location of its emptyweight
center of gravity (EWCG) at the time the certified
aircraft leaves the factory. Amateur-built aircraft must have
this information determined and available at the time of
certification.
The airframe and powerplant (A&P) mechanic or
repairman who maintains the aircraft keeps the weight and
balance records current, recording any changes that have
been made because of repairs or alterations.
The pilot in command of the aircraft has the responsibility
on every flight to know the maximum allowable weight
of the aircraft and its CG limits. This allows the pilot to
determine on the preflight inspection that the aircraft is
loaded in such a way that the CG is within the allowable
limits.
Weight Control
Weight is a major factor in airplane construction and
operation, and it demands respect from all pilots and
particular diligence by all A&P mechanics and repairmen.
Excessive weight reduces the efficiency of an aircraft
and the safety margin available if an emergency
condition should arise.
When an aircraft is designed, it is made as light as the
required structural strength will allow, and the wings or
rotors are designed to support the maximum allowable
weight. When the weight of an aircraft is increased,
the wings or rotors must produce additional lift and the
structure must support not only the additional static loads,
but also the dynamic loads imposed by flight maneuvers.
For example, the wings of a 3,000-pound airplane must
support 3,000 pounds in level flight, but when the airplane
is turned smoothly and sharply using a bank angle of 60°,
the dynamic load requires the wings to support twice this,
or 6,000 pounds.
Severe uncoordinated maneuvers or flight into turbulence
can impose dynamic loads on the structure great enough
1–
to cause failure. In accordance with Title 14 of the Code
of Federal Regulations (14 CFR) part 23, the structure of a
normal category airplane must be strong enough to sustain
a load factor of 3.8 times its weight. That is, every pound
of weight added to an aircraft requires that the structure
be strong enough to support an additional 3.8 pounds.
An aircraft operated in the utility category must sustain a
load factor of 4.4, and acrobatic category aircraft must be
strong enough to withstand 6.0 times their weight.
The lift produced by a wing is determined by its airfoil
shape, angle of attack, speed through the air, and the air
density. When an aircraft takes off from an airport with a
high density altitude, it must accelerate to a speed faster
than would be required at sea level to produce enough
lift to allow takeoff; therefore, a longer takeoff run is
necessary. The distance needed may be longer than the
available runway. When operating from a high-density
altitude airport, the Pilot’s Operating Handbook (POH)
or Airplane Flight Manual (AFM) must be consulted to
determine the maximum weight allowed for the aircraft
under the conditions of altitude, temperature, wind, and
runway conditions.
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