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Refer to figure.
The Dry Operating Index (DOI) calculation and basic index correction information from an aeroplane load and trim sheet are shown in the annex.

Calculate the DOI for an aeroplane mass of 110 800 kg and 31.6% MAC, corrected for one additional flight crew member, with a mass of 85 kg, in zone E.

  • A
    120.4
  • B
    122.2
  • C
    120.7
  • D
    122.0
Refer to figure.

When completing load sheets, particularly for large aircraft, it is convenient to use an Index to represent the large numbers involved and to simplify the calculations.

Generally, Loading Index is a non-dimensional figure that is a scaled down value of a moment and the effect of reducing the magnitude of the moment to one that is much easier to use. For large aircraft, it is convenient to use an index to represent the large numbers involved and to simplify the calculations.

Dry Operating Index (DOI) is the index for the position of the CG at the Dry Operating Mass (DOM).

For this question, according to the figure, the DOI is given by the formula: I = [(CG - 25) x W x 0.029] + 100, where CG is in %MAC and W in 1000 kg. So, the DOI is: [(31.6 - 25) x 110.8 x 0.029] + 100 = 121.2.

The correction on DOI for the additional flight crew member of 85 kg in zone E is: -0.98 x 85 kg/100kg = - 0.8.

Thus, the corrected DOI is: 121.2 - 0.8 = 120.4.

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