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The weight and balance revision sheet should clearly show the revised empty weight, empty weight arm and/or moment index, and the new useful load. An example of these entries can be found at the bottom of Figure 7-3 . 

## Weight Changes Caused by a Repair or Alteration 

A typical alteration might consist of removing two pieces of radio equipment from the instrument panel and a power supply that was located in the baggage compartment behind the rear seat. In this example, these two pieces are replaced with a single lightweight, self-contained radio. At the same time, an old emergency locator transmitter (ELT) is removed from its mount near the tail, and a lighter weight unit is installed. A passenger seat is installed in the baggage compartment. 

Computations Using Weight, Arm, and Moment The first step in the weight and balance computation is to make a chart like the one in Figure 7-4 , listing all of the items that are involved. The new center of gravity (CG) of 36.4 inches aft of the datum is determined by dividing the new moment by the new weight. 

Computations Using Weight and Moment Indexes If the weight and balance data uses moment indexes rather than arms and moments, this same alteration can be computed using a chart such as the one in Figure 7-5 . Subtract the weight and moment indexes of all the removed equipment from the empty weight and moment index of the airplane. Add the weight and moment indexes of all equipment installed to determine the total weight and the total moment index. To determine the position of the new CG in inches aft of the datum, multiply the total moment index by 100 to get the moment, and divide this by the total weight to get the new CG. 

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