Helicopter Weight and Balance

General Concepts

-Helicopter weight and balance is similar to airplanes

-Some differences:

  • More restricted CG range

  • Location and range of CG specified

  • Longitudinal and lateral CG range

  • Helicopter a pendulum hanging from rotor shaft

  • Fuselage horizontal if balanced and CG in range

Helicopter Weighing

-When weighing a helicopter:

  • Know longitudinal and lateral weighing points

  • Longitudinal arms measured from datum

  • Lateral arms measured from butt line

Leveling a Helicopter

-Helicopter must be leveled before weighing

-Plumb bob

-Spirit level

Figure 1

-Leveling Bell Jet Ranger helicopter with plumb bob:

  • Plumb bob attaches inside cabin

  • Floor has plate with crosshairs

  • Plumb moves to low point:

    • Forward of crosshairs, nose too low

    • Left of crosshairs, left side too low

  • Helicopter level if plumb bob point falls in the middle

Weighing a Bell Jet Ranger Helicopter

- Bell Jet Ranger Helicopter

  • Leveling plate in bottom right

  • Three jack pads: 2 front and 1 back

-To weigh:

  • Jack pads placed on floor scales

  • Helicopter raised off floor

-To level:

  • Jacks adjusted until plumb bob falls in crosshairs

Specifications and Weighing Data for Bell Jet Ranger

-Datum 55.16 in forward of front jack point

-Leveling means: plumb bob

-Longitudinal CG limits: 106” to +114.2” at 2,100-3,200 lb

-Lateral CG limits:

  • 2.3” left to 3” right at longitudinal CG +106”

  • 3” left to 4” right at longitudinal CG +108” to +114.2”

  • Fuel and Oil: included in empty eight

  • Left front scale: 650 lb at +55.16” longitudinal, 25” lateral

  • Right front scale: 625 lb at +55.16” longitudinal, 25” lateral

  • Aft scale: 710 lb at +204.92” longitudinal, 0.0” lateral

Example Weighing of Bell Jet Ranger

-Chart below shows calculations for:

  • Empty weight 1,985 lb

  • Longitudinal CG +108.73”

  • Lateral CG -0.31”

Figure 2