WEIGHT AND BALANCE CALCULATIONS
When determining whether your helicopter is properly loaded, you must answer two questions:
1 Is the gross weight less than or equal to the maximum allowable gross weight?
2 Is the center of gravity within the allowable CG range, and will it stay within the allowable range as fuel is burned off?

To answer the first question, just add the weight of the items comprising the useful load (pilot, passengers, fuel, oil, if applicable, cargo, and baggage) to the basic empty weight of the helicopter. Check that the total weight does not exceed the maximum allowable gross weight.
To answer the second question, you need to use CG or moment information from loading charts, tables, or graphs in the rotorcraft flight manual. Then using one of the methods described below, calculate the loaded moment and/or loaded CG and verify that it falls within the allowable CG range shown in the rotorcraft flight manual.
It is important to note that any weight and balance computation is only as accurate as the information provided. Therefore, you should ask passengers what they weigh and add a few pounds to cover the additional weight of clothing, especially during the winter months. The baggage weight should be determined by the use of a scale, if practical. If a scale is not available, be conservative and overestimate the weight. Figure 7-2 indicates the standard weights for specific operating fluids.
Aviation Gasoline (AVGAS) . . . . . . . . . . . . . . . . . . .6 lbs. / gal.� Jet Fuel (JP-4) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.5 lbs. / gal.� Jet Fuel (JP-5) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.8 lbs. / gal.� Reciprocating Engine Oil . . . . . . . . . . . . . . . . . . 7.5 lbs. / gal.*� Turbine Engine Oil . . Varies between 7.5 and 8.5 lbs. / gal.*� Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8.35 lbs. / gal.�
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* Oil weight is given in pounds per gallon while oil capacity� is usually given in quarts; therefore, you must convert the� amount of oil to gallons before calculating its weight.� �
Figure 7-2. When making weight and balance computations, always use actual weights if they are available, especially if the helicopter is loaded near the weight and balance limits.
The following terms are used when computing a helicopter’s balance.
REFERENCE DATUM—Balance is determined by the location of the CG, which is usually described as a given number of inches from the reference datum. The horizontal reference datum is an imaginary vertical plane or point, arbitrarily fixed somewhere along the longitudinal axis of the helicopter, from which all horizontal distances are measured for weight and balance purposes. There is no fixed rule for its location. It may be located at the rotor mast, the nose of the helicopter, or even at a point in space ahead of the helicopter. [Figure 7-3]