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Chapter 16 - Weight and Balance: Let’s Wait & Balance
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much does that weigh? Multiply 30
times 6 pounds/gallon=180 pounds.
The fuel tanks are located at an arm Fig. 11
of 96.0 inches aft of the datum. What
moment does the fuel produce?
Multiply 180 pounds times 96.0 inch-
es=17,280 lb-in.
To find the CG for the loaded air-
plane you must divide the total
moments by the total weights.
Remember, all three arms that are
shown in the middle column of
Figure 11A are only used in comput-
ing the moments. The arms aren’t
added since this would serve no pur-
pose. The next time that you will use
the concept of arm is when you
divide the airplane’s total moment
by its total weight. The arm or dis-
tance is now the point where the full
airplane would balance (i.e., its cen-
ter of gravity).

Weight X Arm=Moment
Arm (CG)=Total Moments
Total Weight
The total weight is 2,070 pounds.
The total moments are 193,673 lb-in.
Divide the total moments by the
total weight to get the CG arm (the
distance from the datum where the
weights balance). Dividing 193,673
by 2070=93.6 inches—the center of
gravity as shown in Figure 11B.
Considering that forward and aft
CG limits are usually expressed in appropriate limits for safe flight. was 97.3 inches. In this instance,
inches past the datum line, we can Suppose the forward CG limit was the airplane falls within the proper
easily tell if the CG is within the set at 89.0 inches and the aft limit CG limits.

Determining Cargo Pallet Loads and Floor Loading Limits
This may surprise you but as a private pilot, you can fly an airplane large enough to carry small pallets. Therefore, you should
know something about the weight limits of the floor where these pallets can be placed in an airplane.
The cargo or baggage area of an airplane has a load limit based on the structural integrity of that area. Think about it this way, if
an airplane has a limit load factor of 3.8+Gs, then a 100 pound cargo load limit means the cargo area is stressed to hold 380
pounds without experiencing damage. Exceed these weight limits and baggage area is subject to damage in high-G conditions.
To determine the maximum weight of a loaded cargo pallet that can be carried in a cargo hold, divide its total weight, which
includes the weight of the empty pallet and its tie down devices, by its area in square feet. This load per square foot must be equal
to or less than the floor load limit.
In this example, determine the maximum load that can be placed on this pallet without exceeding the floor-loading limit.
Pallet dimensions..........................................36 by 48 in
Empty pallet weight................................................47 lb
Tie down devices....................................................33 lb
Floor load limit ............................169 lb per square foot
The pallet has an area of 36 inches (3 feet) by 48 inches (4 feet), which equals 12 square feet, and the floor has a load limit of 169
pounds per square foot. Therefore, the total weight of the loaded pallet can be 169 × 12 = 2,028 pounds. Subtracting the weight of
the pallet and the tie down devices gives an allowable load of 1,948 pounds (2,028 – [47 + 33]).