4.
 Use the measured values in the formula for determining the center of gravity of the empty airplane;

-Port wheel………………………………………………...lb -Starboard wheel…………………………………………..lb -Nose wheel……………………………………………….lb -Total weight………………………………………………lb
Weight on nose wheel x d distance
-= ……………………LCG of empty airplane
Total weight
The C.G. position in relation to the datum line is:
XCG empty airplane = 24,68" - LCG empty airplane, then calculate the C.G.:

XCG empty airplane
X 100 = C.G. of empty airplane
6 0"

The empty airplane center of gravity is 23.69″±1% MAC.
The operational center of gravity may vary with every loading case. Consequently, the center of gravity must be calculated for each particular situation. For calculating the operational center of gravity, use the following distances for added load (add-ons): -Datum line = wing leading edge
-Distance  - pilot to passenger = 18.9"
-fuel          = 15.51"
The calculation method for the center of gravity position (XCG) of the airplane at take-off is shown below:
S.C. AEROSTAR  S.A.
FESTIVAL R40S
BACAU - ROMANIA
   AIRPLANE MAINTENANCE MANUAL
2 Item no. Load (lb) 1 4 Fuel=Wfuel  Pilot and passenger=Wpilot+passenger= Wpilot+Wpassenger Weight of empty airplane = Wempty  18.9 . XCG empty airplane X (inch) 23.39"  Wpilot+passenger*18.9" Wempty*XCG empty airplane Momentum ((lb x (inch)) Wfuel*23.39" 

            By consequence:
Wempty xXCGemptyairplane + (Wpilot + Wpassenger )x18.9''+W fuel x23.39''
XCG =

airplane
W + W + W + W
empty pilot passenger fuel
This will give us the C.G. position, in percentage:
XCG airplane
* 100 = C.G. of equipped airplane
60"

Below you can see the maximum allowed limits of the c.g. during aircraft operation: -Maximum allowed limit, forward = 10.79" (24% MAC) -Maximum allowed limit, rearward = 18" (30 % MAC)
1.5.5. Methods for adjusting the LCG
The LCG of an empty (equipped) airplane - can be adjusted only by changing the position of the storage battery.
CAUTION: The LCG of an atypically loaded airplane is adjusted by placing and fastening the loads in such a way as to ensure observance of the allowed CG limits for flight, and not to exceed the maximum take-off weight.
　
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