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Which statement about CG limits is correct?
  • A
    The forward CG limit is mainly determined by the amount of pitch control available from the elevator.
  • B
    If the aft CG limit is correctly chosen, the forward CG limit is automatically determined as well.
  • C
    The forward CG limit is determined by stability considerations only.
  • D
    The aft CG limit is determined by the maximum elevator deflection available.
The range within which the CG must always be located for safe operations is the CG envelope that, for transport aeroplanes, is defined as the area between the safe forward limit approximately 10% MAC and the safe aft limit approximately 30% MAC.
  • The forward limit: The forward limit of the envelope is determined by the amount of pitch control available from the elevators; that is the degree of manoeuvrability that an aeroplane of that type commands. With the CG in this position, the aeroplane has the greatest longitudinal stability. In the landing configuration, maximum elevator-up deflection is required when the CG is at the forward limit and full flap is selected.

  • The aft limit: The aft limit, which for safety reasons on a transport aeroplane is always forward of the neutral point, is confined by insufficient stick-force stability and/or excessive in-flight manoeuvrability. A CG position aft of this point would produce an unacceptably low value of manoeuvre stability and would make the aeroplane difficult to fly.

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