AIRPLANE
OPERATIONS
MANUAL
WEIGHT AND
BALANCE
REVISION 29
1-06-40
Page
19
Code
03
FUEL ALLOWANCES:
There are some conditions under which it is possible to have both
ZFW-CG and TOW-CG located inside the CG envelope and the
LW-CG outside of the CG envelope (see Figure 1).
26000
28000
30000
32000
34000
36000
38000
40000
42000
44000
46000
48000
50000
52000
10 20 30 40 50 60 70 80 90
INDEX
WEIGHT (lb) a-a
15% 20% 25%
40%
35%30%
45%
ZFW
TOW
Figure 1
In order to prevent the LW CG from being located outside of the CG
envelope, the idea is to determine a constrained ZFW envelope.
CONSTRAINED ZFW LIMITS
In order to determine the constrained ZFW CG envelope, it is
necessary to convert the constrained CG envelope to the index system
and then apply the fuel allowances.
Converting the previously defined forward and aft limits to the index
system using the formula:
()
13
17400
590armW
I +
−×
=
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