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B is moved from +80 to +25.
Moving weight B from +80 to +25 will move the CG 22
inches, from its original location at +72 to its new location
at +50 as seen in Figure 2-13.
Shifting the Airplane CG
The same procedures for shifting the CG by moving
weights can be used to change the CG of an airplane by
rearranging passengers or baggage.
Consider this airplane:
Airplane empty weight and EWCG 1340 lbs @ +37.0
Maximum gross weight................................. 2,300 lbs
CG limits............................................... +35.6 to +43.2
Front seats (2)........................................................ +35
Rear seats (2)......................................................... +72
Fuel.........................................................40 gal @ +48
Baggage (maximum).............................. 60 lbs @ +92
Figure 2-15. Loading diagram for a typical single-engine airplane.
The pilot has prepared a chart, Figure 2-16, with certain
permanent data filled in and blanks left to be filled in with
information on this particular flight.
Figure 2-16. Blank loading chart.
2–
For this flight, the 140-pound pilot and a 115-pound
passenger are to occupy the front seats, and a 212-pound
and a 97-pound passenger are in the rear seats. There
will be 50 pounds of baggage, and the flight is to have
maximum range, so maximum fuel is carried. The loading
chart, Figure 2-17, is filled in using the information from
Figure 2-15.
Figure 2-17. This completed loading chart shows the weight is within
limits, but the CG is too far aft.
With this loading, the total weight is less than the
maximum of 2,300 pounds and is within limits, but the CG
is 0.9 inch too far aft.
One possible solution would be to trade places between the
212-pound rear-seat passenger and the 115-pound frontseat
passenger. Use a modification of the basic weight and
balance equation to determine the amount the CG will
change when the passengers swap seats.
The two passengers changing seats moved the CG forward
1.6 inches, which places it within the operating range. This
can be proven correct by making a new chart incorporating
the changes. [Figure 2-18]
Figure 2-18. This loading chart, made after the seat changes, shows
both the weight and balance are within allowable limits.
Weight and Balance Documentation
FAA-Furnished Information
Before an aircraft can be properly weighed and its emptyweight
center of gravity computed, certain information
must be known. This information is furnished by the
FAA to anyone for every certificated aircraft in the Type
Certificate Data Sheets (TCDS) or Aircraft Specifications
and can be accessed via the internet at: www.faa.gov
(home page), from that page, select “ Regulations and
Policies,” and at that page, select “Regulatory and
Guidance Library.” This is the official FAA technical
reference library.
When the design of an aircraft is approved by the FAA,
an Approved Type Certificate and TCDS are issued. The
TCDS includes all of the pertinent specifications for the
aircraft, and at each annual or 100-hour inspection, it is
the responsibility of the inspecting mechanic or repairman
to ensure that the aircraft adheres to them. See pages 2-
7 through 2-9, for examples of TCDS excerpts. A note
about the TCDS: aircraft certificated before January 1,
1958, were issued Aircraft Specifications under the Civil
Air Regulations (CARs), but when the Civil Aeronautical
Administration (CAA) was replaced by the FAA, Aircraft
Specifications were replaced by the Type Certificate Data
Sheets. The weight and balance information on a TCDS
includes the following:
Data Pertinent to Individual Models
This type of information is determined in the sections
pertinent to each individual model:
CG Range
Normal Category
(+82.0) to (+93.0) at 2,050 pounds.
(+87.4) to (+93.0) at 2,450 pounds.
Utility Category
(+82.0) to (+86.5) at 1,950 pounds.
Straight-line variations between points given.
2–
Figure 2-19. Excerpts from a Type Certificate Data Sheet.
2–
Figure 2-19. Excepts for a Type Certificate Data Sheet (continued)
2–
Figure 2-19. Excepts for a Type Certificate Data Sheet (continued)
2–10
If this information is given, there may be a chart on the
TCDS similar to the one in Figure 2-20. This chart helps
visualize the CG range. Draw a line horizontally from
the aircraft weight and a line vertically from the fuselage
station on which the CG is located. If these lines cross
inside the enclosed area, the CG is within the allowable
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Aircraft Weight and Balance Handbook(11)
