WEIGHT AND
BALANCE
AIRPLANE
OPERATIONS
MANUAL
1-06-40
Page
6
Code
03
REVISION 29
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. This behavior is caused by the
particular fuel loading characteristics of the aircraft, where the initial
fuel loaded causes a forward moment and then higher fuel loading
causes an aft moment (see the fuel index tables, where light fuel loads
result in negative indexes and high fuel loads results in positive
indexes).
In order to prevent the LW CG from being located outside of the CG
envelope, the idea is to determine a constrained ZFW envelope, in
which the fuel loading curve is always located inside the CG envelope.
CONSTRAINED CENTER OF GRAVITY LIMITS
In order to determine the constrained CG envelope, the allowances
must be added to the certified CG 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.
When the fuel quantity is equal to or less than the one specified in the
table below, the ZFW envelope without constraint may be used,
because fuel burn always makes the CG move backward. In this case,
it must be checked if ZFW-CG, TOW-CG and LW-CG are located
inside the CG envelope.
Model Fuel Weight (lb)
EMB-135 ER 3527
EMB-135 LR 6349
EMB-145 STD, EU, EP, ER,
MP and MK
3175
EMB-145 LU and LR 5291
To Next Page
Loading...
