Weight and Balance

Study Materials

AMT-G, FAA-H-8083-1, FAA-H-8083-30, AC 43.13-1

Typical Oral Questions

  1. Where must a record be kept of the current empty weight and the current center of gravity of an aircraft?

    In the aircraft flight manual or weight and balance records required by 14 CFR §23.1583.

  2. What is meant by the datum that is used for weight and balance computations?

    A readily identified reference chosen by the aircraft manufacturer from which all longitudinal locations on the aircraft are referenced.

  3. Why are the distances of all of the items installed in an aircraft measured from the datum when computing weight and balance?

    This makes it possible to find the point about which the aircraft would balance (the center of gravity).

  4. What are two reasons weight and balance control are important in an aircraft?

    For safety of flight and for most efficient performance of the aircraft.

  5. What is meant by moment in the computation of weight and balance?

    A force that tends to cause rotation. It is the product of the weight of an object in pounds and the distance of the object from the datum in inches.

  6. How do you find the moment of an item that is installed in an aircraft?

    Multiply the weight of the item in pounds by its distance from the datum in inches.

  7. What is meant by the arm of an item that is installed in an aircraft?

    The distance, in inches, between the center of gravity of the item and the datum.

  8. Why must we consider the category under which an aircraft is licensed when we compute its weight and balance?

    The different categories under which an aircraft can be licensed have different maximum gross weights and different center of gravity ranges.

  9. Where can you find the leveling means that are specified for a particular aircraft?

    In the Type Certificate Data Sheets for the aircraft.

  10. Where is the arm of an item installed in an aircraft recorded?

    In the Type Certificate Data Sheets for the aircraft.

  11. What must be done to find the empty weight of an aircraft if it has been weighed with fuel in its tanks?

    The weight of the fuel and its moment must be subtracted from the weight and moment of the aircraft as it was weighed.

  12. What is meant by the tare weight that is used in a weight and balance computation?

    The weight of the chocks and other items that are used to hold the aircraft on the scales.

  13. What must be done to the tare weight when an aircraft is weighed?

    It must be subtracted from the scale reading to find the weight of the aircraft.

  14. What is meant by minimum fuel as is used in the computation of aircraft weight and balance?

    No more fuel than the quantity necessary for one-half hour of operation at rated maximum continuous power. It is the maximum amount of fuel used in weight and balance computations when low fuel may adversely affect the most critical balance conditions.

  15. What is meant by the maximum zero fuel weight of an aircraft?

    The maximum permissible weight of a loaded aircraft (passengers, crew, cargo, etc.), less its fuel.

  16. What is meant by undrainable fuel?

    The fuel that is left in the tank, lines and components when the aircraft is placed in level flight position and the fuel drained at the main fuel strainer. This is also called residual fuel.

  17. Describe the way you would find the empty weight and empty weight center of gravity of an airplane if there are no weight and balance records available.

    The aircraft is weighed, and the empty weight center of gravity is computed. These values are recorded in new weight and balance records that are started for the aircraft.

  18. What is meant by permanent ballast for an aircraft?

    Weight that is permanently installed in an aircraft to bring the empty weight center of gravity into allowable limits.

  19. Which has the more critical center of gravity range, an airplane or a helicopter?

    A helicopter.

  20. What equipment must be installed in an aircraft when it is weighed to find its empty weight center of gravity?

    All of the equipment that is listed in the Aircraft Equipment List as “required equipment” or as equipment that is permanently installed.

  21. What is the significance of the empty weight center of gravity range of an aircraft?

    If the empty weight center of gravity falls within the EWCG range, the aircraft cannot be legally loaded in such a way that its loaded center of gravity will fall outside of the allowable loaded CG range. Not all aircraft have an EWCG range.

  22. Why is empty weight center of gravity range not given in the Type Certificate Data Sheets for some aircraft?

    The empty weight center of gravity range is given only for aircraft that cannot be legally loaded in such a way that their loaded center of gravity will fall outside of the allowable limits.

Typical Practical Projects

  1. Find the new empty weight and empty weight center of gravity for this aircraft after it has been altered by removing two seats and replacing them with a cabinet, one seat, and some radio gear.

    Aircraft empty weight = 2,886 pounds

    Empty weight total moment = 107,865.78

    Each removed seat weighs 15 pounds, located at station 73.

    Installed cabinet weighs 97 pounds, installed at station 73.

    New seat weighs 20 pounds, installed at station 73.

    Radio gear weighs 30 pounds, installed at station 97.

  2. Find the amount of ballast that is needed to bring this aircraft into its proper center of gravity range:

    Aircraft as loaded weighs 4,954 pounds.

    Aircraft loaded center of gravity is +30.5 inches aft of the datum.

    Loaded center of gravity range is +32.0 to +42.1 inches aft of the datum.

    The ballast arm is +162 inches.

  3. Find the distance in inches to the left of the fulcrum that a box, weighing 20 pounds, would have to be placed in order to balance a board that contains a box weighing 10 pounds located four feet to the right of the fulcrum, and one weighing five pounds that is located two feet to the right of the fulcrum.
  4. Find the empty weight and the empty weight center of gravity of an airplane that has the following scale weights:

    Left main wheel = 1,765 pounds, arm = +195.5 inches

    Right main wheel = 1,775 pounds, arm = +195.5 inches

    Nosewheel = 2,322 pounds, arm = +83.5 inches

  5. Find the empty weight and empty weight center of gravity of an aircraft that is specified by the examiner.
  6. Find the center of gravity of a fully loaded aircraft specified by the examiner.
  7. Find the amount of fuel that is needed by an aircraft specified by the examiner as the minimum fuel for an adverse loaded center of gravity condition.
  8. Prepare an aircraft specified by the examiner for weighing.
  9. Find the loaded weight and the loaded weight center of gravity of a helicopter specified by the examiner. Determine whether or not it falls within its weight and center of gravity limits.
  10. Use the center of gravity envelope in a weight and balance report to find the forward and aft center of gravity limits for a specified weight of the aircraft.
  11. Locate the datum of an aircraft specified by the examiner, using the appropriate Type Certificate Data Sheets.
  12. Using the appropriate document, locate the jacking points of an airplane. Explain to the examiner the precautions that should be taken when jacking the aircraft.

[10-2024]