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Prior to every Commercial Air Transport flight of a large aircraft, the Operator uses an electronic or a paper format trim sheet to determine the Centre of Gravity of the actual Zero Fuel Mass, Take-Off Mass and Landing Mass. What is the purpose of the trim sheet?
  • A
    This is to check that they are below the limits published in the Aircraft flight Manual, and is achieved by calculating the moments.
  • B
    This is to ensure that the CGs are within the certified envelope, and is achieved by using the index method.
  • C
    This is done by referring to the stations of various fuselage sectors defined in mass and balance documentation.
  • D
    This is done by computing the balance arm of the actual operational masses and the results are given in metres or inches.

Refer to figure.
Load/Trim sheet is a document which enables the Pilot-in-Command to determine that both the aircraft's load and its distribution throughout the fuselage are such that the mass and balance limits of the aircraft are not exceeded.

The Load/Trim sheet is in two parts:

  • Part A (to the left) is a loading summary. Moreover, Part A is divided into three Sections. Section 1 (top) is used to establish the Limiting Take-off Mass and the Maximum AllowableTraffic Load that can be carried, Section 2 (middle) shows the traffic load distribution and Section 3 (bottom) sums up the load and cross checks that any limit has not been exceeded.
  • Part B (to the right) is the trim portion, which helps to establish the CG %MAC and ensure that it lies within the certified envelope. It is where we plot graphically the positions of the CG of operational masses, such as Take off Mass, Zero Fuel Mass and Landing Mass.
​​​​​​When completing load sheets, particularly for large aircraft, it is convenient to use an Index method to represent the large numbers involved and to simplify the calculations.

Generally, Loading Index is a non-dimensional figure (i.e. a figure without unit of measurement) 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.

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