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Examples of typical weight and balance problems (solved with an electronic calculator) that pilots and airframe and powerplant (A&P) maintenance technicians encounter throughout their aviation endeavors are shown later in this chapter. 

## Electronic Calculator 

Determining the CG of an airplane in inches for the main- wheel weighing points can be done with any simple electronic calculator that has addition (+), subtraction (–), multiplication (×), and division (÷) functions. [Figure 10-1] Scientifi calculators with such additional functions as memory (M), parentheses (( )), plus or minus (+/–), exponential (y$^{x}$), reciprocal (1/x), and percentage (%) functions allow more complex problems to be solved or simple problems to be solved using fewer steps. 

<img src='content_image/591021.jpg'>

According to Figure 10-2 , the weight of the nosewheel (F) is 340 pounds, the distance between main wheels and nosewheel (L) is –78 inches, and the total weight (W) of the airplane is 2,006 pounds. L is negative because the nosewheel is ahead of the main wheels. 

<img src='content_image/591019.jpg'>

To determine the CG, use this formula: 

<img src='content_image/591016.jpg'>

Key the data into the calculator and press the equal (=) key. The answer should read as follows: 

<img src='content_image/591015.jpg'>

The arm of the nosewheel is negative, so the CG is –13.2 or 13.2 inches ahead of the main wheel weighing points. 

## E6-B Flight Computer 

The E6-B uses a special kind of slide rule. Instead of its scales going from 1 to 10, as on a normal slide rule, both scales go from 10 to 100. The E6-B cannot be used for addition or subtraction, but it is useful for making calculations involving multiplication and division. Its accuracy is limited, but it is sufficiently accurate for most weight and balance problems. 

The same problem that was just solved with the electronic calculator can be solved on an E6-B by following these steps: 

<img src='content_image/591014.jpg'>

First, multiply 340 by 78 (disregard the minus sign) [Figure 10-3] : 

• Step 1—place 10 on the inner scale (this is the index opposite 34 on the outer scale that represents 340). 

• Step 2—opposite 78 on the inner scale, read 26.5 on the outer scale. 

Determine the value of these digits by estimating: 300 × 80 = 24,000, so 340 × 78 = 26,500. 

Then, divide 26,500 by 2,006 [Figure 10-4] : 

