C42E 540kg LSA POH Issue 3 China
15.03.2016
Page 22 of 36
6
WEIGHT AND BALANCE
6.1
Weight and balance calculations
The centre of gravity is measured in mm behind the zero datum. Zero datum is the leading edge root.
The aircraft’s empty weight and cg are derived first: Place the aircraft in a level position on three scales,
such that the stabilizer is horizontal (0°), as shown below. Therefore lift the wing or push down the rear
fuselage just in front of the tail and put a distance below the scales to level the aircraft. Record the
reading of each scale.
a = 770mm
b= 1540mm
Calculate the position of the empty cg, from the formula:
mm
G
G
b
G
a
......
..........
X
2
1
1
=
+
×
−
=
(a and b are values to be measured for the specific aircraft).
Insert the values for total empty weight, (G
1
+ G
2
) and cg distance aft of datum, (X), into the table below.
Multiply Empty Weight (kg) by cg distance aft of datum (mm) to derive empty weight moment (kg.mm)
in the last column.
Complete the remaining weights for seat loads, fuel and baggage and multiply these by the lever arm
lengths (given below).
Add up the weights and moments, then divide the total weight by the total moment to give laden cg
location aft of datum.
Ensure that this cg location lies within the limits 350 to 523 aft of datum.
a
x
G
1
G
2
= G
L
+ G
R
b
