6-8 P/N 13999-002 Info Manual
Section 6 Cirrus Design
Weight & Balance SR20
4. Measuring (Figure 6-3):
a. Obtain measurement ‘x’ by measuring horizontally along the
airplane center line (BL 0) from a line stretched between the
main wheel centers to a plumb bob dropped from the forward
side of the firewall (FS 100). Add 100 to this measurement to
obtain left and right weighing point arm (dimension ‘A’).
Typically, dimension ‘A’ will be in the neighborhood of 157.5.
b. Obtain measurement ‘y’ by measuring horizontally and
parallel to the airplane centerline (BL 0), from center of
nosewheel axle, left side, to a plumb bob dropped from the
line stretched between the main wheel centers. Repeat on
right side and average the measurements. Subtract this
measurement from dimension ‘A’ to obtain the nosewheel
weighing point arm (dimension ‘B’).
5. Determine and record the moment for each of the main and nose
gear weighing points using the following formula:
Moment = Net Weight x Arm
6. Calculate and record the as-weighed weight and moment by
totaling the appropriate columns.
7. Determine and record the as-weighed C.G. in inches aft of datum
using the following formula:
C.G. = Total Moment / Total Weight
8. Add or subtract any items not included in the as-weighed condition
to determine the empty condition. Application of the above C.G.
formula will determine the C.G for this condition.
9. Add the correction for engine oil (15 lb at FS 78.4), if the airplane
was weighed with oil drained. Add the correction for unusable fuel
(26.4 lb at FS 153.95) to determine the Basic Empty Weight and
Moment. Calculate and record the Basic Empty Weight C.G. by
applying the above C.G. formula.
10. Record the new weight and C.G. values on the Weight and
Balance Record.
September 2011
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