5 / 20

After the weighing of an aircraft by the maintenance personnel, the following data is obtained from reaction forces on the jacking points:

Each of the 2 main landing gear jack points: 156 500 N 
Aft fuselage jack point: 65 200 N

The longitudinal distance between the main landing gear jack points and the aft fuselage jack point is 12.8 m. Assuming the datum line is positioned at the main landing gears, the Basic Empty Mass is (1) _____, and its associated longitudinal CG position is (2) _____ of the datum. 
(Consider g = 10 m/s2, and calculation accuracy: rounded to the nearest one decimal place)

  • A

    (1) 22 170 kg; (2) 3.8 m aft

  • B

    (1) 378 200 kg; (2) 2.2 m forward

  • C

    (1) 37 820 kg; (2) 2.2 m aft

  • D

    (1) 37 820 kg; (2) 3.8 m aft

Note:

  • This question is NOT using the standard nose wheel jacking point: There is an aft fuselage jacking point. This is typical with a tail dragger type aircraft, such as the DC3.
  • The datum is placed on the main gear
  • This means that the moments calculated at the aft fuselage jacking point will be positive / aft of datum and so the CG can be anticipated to be aft of datum, which already rules out one of the possible answers.

First job: convert the Newtons into KG using the direction given in the question: Consider g = 10 m/s2

  • Each main landing gear jack point: 156 500 N / 10 = 15 650 kg
  • Aft fuselage jack point: 65 200 N / 10 = 6520 kg
ItemMass (kg)Arm (m)Moment (kg.m)
Aft fuselage jack6520+12.8+83 456
Left main wheel jack15 65000
Right main wheel jack15 65000
BEM37 820CG = +2.2+83 456


Therefore, the aircraft's BEM is 37 820 kg and the CG position is 2.2 m aft of datum.

Your Notes (not visible to others)



This question has appeared on the real examination, you can find the related countries below.

  • Austro Control
    8
  • France
    8
  • Poland
    7
  • Spain
    4
  • Italy
    3
  • Greece
    2
  • Portugal
    2
  • Iceland
    1
  • Lithuania
    1
  • Norway
    1
  • Romania
    1
  • Serbia
    1
  • Sweden
    1
Keyboard Shortcut Use Keyboard Shortcuts