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Weight and Balance Handbook

FAA-H-8083-1B Version 2016
All Library Documents FAA Source

Chapter 9

Weight and Balance Control—Commuter Category and Large Aircraft

Figure 9-36. Determining the amount of weight the aircraft must lose to reach the maximum allowable landing weight.
Figure 9-36. Determining the amount of weight the aircraft must lose to reach the maximum allowable landing weight.
Figure 9-37. Determining the amount of fuel burned from the beginning of the dump to touchdown.
Figure 9-37. Determining the amount of fuel burned from the beginning of the dump to touchdown.

For both engines, this is 52.83 × 2 = 105.66 lb/minute.

The engines burn 105.66 lbs of fuel per min for 19 minutes (the duration of the dump), which calculates to 2007.54 pounds of fuel burned between the beginning of the dump and touchdown.

  1. Determine the amount of fuel needed to dump by subtracting the amount of fuel burned during the dump from the required weight reduction. [Figure 9-38]
  2. Determine the time needed to dump this amount of fuel by dividing the number of pounds of fuel to dump by the dump rate. [Figure 9-39]
Figure 9-38. Determining the amount of fuel needed to dump.
Figure 9-38. Determining the amount of fuel needed to dump.
Figure 9-39. Determine the time needed to dump fuel.
Figure 9-39. Determine the time needed to dump fuel.

Weight and Balance of Commuter Category Airplanes

The Beech 1900 is a typical commuter category airplane that can be configured to carry passengers or cargo. Figure 9-40 shows the loading data of this type of airplane in the passenger configuration.

Figure 9-40. Loading data for passenger configuration.
Figure 9-40. Loading data for passenger configuration.

Determining the Loaded Weight and CG

As this airplane is prepared for flight, a manifest is prepared. [Figure 9-41]

Figure 9-41. Determining the loaded weight and CG of a Beech 1900 in the passenger configuration.
Figure 9-41. Determining the loaded weight and CG of a Beech 1900 in the passenger configuration.
  1. The crew weight and the weight of each passenger is entered into the manifest. 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. [Figure 9-42]
  2. The weight of the baggage in each compartment used is entered with its moment/100. This is determined in the Weights and Moments—Baggage table. [Figure 9-43]
  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 Density Variation of Aviation Fuel Chart [Figure 9-44], it weighs 6.75 lb/gal. Using this chart, determine the weights and moment/100 for 390 gallons of Jet A fuel by interpolating between those for 6.7 lb/gal and 6.8 lb/gal. The 390 gallons of fuel at this temperature weighs 2,633 pounds, and its moment index is 7,866 lb-in/100.
  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. [Figure 9-45]
  5. Check to determine that the CG is within limits for this weight. Refer to the Weight and Balance Diagram. [Figure 9-46] 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 the datum. These lines cross inside the envelope, verifying the CG is within limits for this weight.
Figure 9-42. Weight and moments—occupants.
Figure 9-42. Weight and moments—occupants.
Figure 9-43. Weight and moments—baggage.
Figure 9-43. Weight and moments—baggage.
Figure 9-44. Density variation of aviation fuel.
Figure 9-44. Density variation of aviation fuel.
Figure 9-45. Weights and moments—usable fuel.
Figure 9-45. Weights and moments—usable fuel.
Figure 9-46. Weight and balance diagram.
Figure 9-46. Weight and balance diagram.

Determining the Changes in CG When Passengers Are Shifted