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one in Figure 6-7 is prepared.
1. The crew weight and the weight of each passenger is
entered into the manifest, and the moment/100 for each
occupant is determined by multiplying the weight by the
arm and dividing by 100. This data is available in the AFM
and is shown in the Weight and Moments—Occupants
table in Figure 6-8 on Page 6-14.
2. The weight of the baggage in each compartment that is
used is entered with its moment/100. This is determined
in the Weights and Moments—Baggage table in Figure
6-9 on Page 6-14.
3. Determine the weight of the fuel. Jet A fuel has a nominal
specific gravity at +15°C of 0.812 and weighs 6.8 pounds
per gallon, but at +25°C, according to the chart in Figure
6-10 on Page 6-15, it weighs 6.75 lbs/gal.
Using Figure 6-11 on Page 6-16, determine the weights
and moment/100 for 390 gallons of Jet A fuel by
interpolating between those for 6.7 lbs/gal and 6.8 lbs/gal.
The 390 gallons of fuel at this temperature weighs 2,633
pounds, and its moment index is 7,866 lb-in/100.
Figure 6-6. Loading data for passenger configuration.
Jet Fuel Weight Affected by Temperature
The colder the fuel, the more dense and therefore the more pounds
of fuel per gallon.
(Continued on Page 6-17)
6 – 14
Figure 6-7. Determining the loaded weight and CG of a Beech 1900 in the passenger configuration.
Figure 6-8. Weights and moments—occupants.
Figure 6-9. Weights and moments—baggage.
6 – 15
Figure 6-10. Density variation of aviation fuel.
6 – 16
Figure 6-11. Weights and moments—usable fuel.
Figure 6-12. Weight and balance diagram.
6 – 17
This type of problem is usually solved by using these two
formulas (below). The total amount of weight shifted is 550
pounds (300 + 250) and both rows of passengers have moved
aft by 210 inches (410 – 200 and 440 – 230).
4. Add all of the weights and all of the moment indexes.
Divide the total moment index by the total weight, and
multiply this by the reduction factor of 100. The total
weight is 14,729 pounds, the total moment index is 43,139
lb-in/100. The CG is located at fuselage station 292.9.
5. Check to determine that the CG is within limits for this
weight. Refer to the Weight and Balance Diagram in
Figure 6-12 on Page 6-16. Draw a horizontal line across
the envelope at 14,729 pounds of weight and a vertical
line from the CG of 292.9 inches aft of datum. These lines
cross inside the envelope verifying the CG is within limits
for this weight.
Determining the Changes in CG When
Passengers are Shifted
Consider the airplane above for which the loaded weight and
CG have just been determined, and determine the change in
CG when the passengers in rows 1 and 2 are moved to rows
8 and 9. Figure 6-13 shows the changes from the conditions
shown in Figure 6-7. There is no weight change, but the
moment index has been increased by 1,155 pound-inches/100
to 44,294. The new CG is at fuselage station 300.7.
The CG has been shifted aft 7.8 inches and the new CG is
at station 300.7.
Figure 6-13. Change in CG caused by shifting passenger seats.
6 – 18
Figure 6-14. Loading data for cargo configuration.
Determining Changes in Weight and CG When
the Airplane is Operated in its Cargo
Configuration
Consider the airplane configuration shown in Figure 6-14.
The airplane is loaded as recorded in the table in Figure
6-15. The basic operating weight (BOW) includes the pilots
and their baggage so there is no separate item for them.
The arm of each cargo section is the centroid of that section,
as is shown in Figure 6-14.
The fuel, at the standard temperature of 15°C weighs 6.8
pounds per gallon. Refer to the Weights and Moments—
Usable Fuel in Figure 6-11 on Page 6-16 to determine the
weight and moment index of 370 gallons of Jet A fuel.
The CG under these loading conditions is located at station
296.2.
Determining the CG Shift When Cargo is Moved
From One Section to Another
When cargo is shifted from one section to another, use this
formula:
Figure 6-15. Flight manifest of a Beech 1900 in the cargo configuration.
If the cargo is moved forward, the ? CG is subtracted from
the original CG. If it is shifted aft, add the ? CG to the
original.
6 – 19
Determining the CG Shift When Cargo
is Added or Removed
When cargo is added or removed, add or subtract the weight
and moment index of the affected cargo to the original
loading chart. Determine the new CG by dividing the new
moment index by the new total weight, and multiply this by
　
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