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Aviation Maintenance Technician Handbook–General

FAA-H-8083-30B Version 2023
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Chapter 6

Aircraft Weight & Balance

Formula: CG – LEMAC ; Percent of MAC = × 100 ; MAC

The result using the numbers shown in Figure 6-52 would be:

Formula: CG – LEMAC ; Percent of MAC = × 100 ; MAC
Figure 6-48. Bell JetRanger.
Figure 6-48. Bell JetRanger.
Figure 6-49. Specifications and weighing data for Bell JetRanger.
Figure 6-49. Specifications and weighing data for Bell JetRanger.
Figure 6-50. Center of gravity calculation for Bell JetRanger.
Figure 6-50. Center of gravity calculation for Bell JetRanger.
Figure 6-51. Weight and balance for a weight-shift control aircraft.
Figure 6-51. Weight and balance for a weight-shift control aircraft.
Figure 6-52. Wing attach point for a weight-shift control aircraft.
Figure 6-52. Wing attach point for a weight-shift control aircraft.
Figure 6-53. Powered parachute structure with wing attach points.
Figure 6-53. Powered parachute structure with wing attach points.

If the CG is known in percent of MAC, and there is a need to know the CG location in inches from the datum, the conversion would be done as follows:

  1. Convert the percent of MAC to a decimal by dividing by 100.
  2. Multiply the decimal by the length of the MAC.
Figure 6-54. Center of gravity location on a large commercial transport.
Figure 6-54. Center of gravity location on a large commercial transport.

an inch value would be:

Formula: CG in inches = % MAC ÷ 100 × MAC + LEMAC

For the airplane in Figure 6-54, if the CG was at 32.5 percent of the MAC, the solution would be:

Formula: C G i n i n c h e s = % MAC ÷ 100 × MAC + LEMAC ; = 32.5 ÷ 100 × 180 + 900 ; = 958.5

Weight & Balance Records

When a technician gets involved with the weight and balance of an aircraft, it almost always involves a calculation of the aircraft’s empty weight and EWCG. Only on rare occasions are technicians involved in calculating adverse-loading CG ort.

checks, how much ballast is needed, or the loaded weight and balance of the aircraft. Calculating the empty weight and EWCG might involve putting the aircraft on scales and weighing it, or a pencil and paper exercise after installing a new piece of equipment.

The FAA requires that a current and accurate empty weight and EWCG be known for an aircraft. This information must be included in the weight and balance report, which is a part of the aircraft permanent records. The weight and balance report must be in the aircraft when it is being flown.