C 2500 ECG determination method = ±2.55 index units = ± 2.55 x 2500 = ± 6374 kg.m.
C. BALANCE CHART DESIGN
3.6. Item movements during flight impacting the aircraft CG position
Aircraft CG positions computed on the balance chart are based on DOW and DOCG values.
DOW and DOCG values are published for the following configuration : . Flaps/slats in clean position . Landing Gear extended . Reversers in retracted position . Water in potable water tanks.
This configuration corresponds to the aircraft configuration used at aircraft weighing.
Note : the above mentioned configuration at DOW is the most common one, some operators may use a different configuration. In this case the below presented method has to be adapted. Note : on all the aircraft the movement of the reversers is considered negligible in term of CG movements so they are no more considered below.
The computed aircraft CG positions during the flight are computed for a given configuration in the cabin, passengers and crew seated in Takeoff/Landing configuration and trolleys locked in the galleys. During the flight, passengers and crew members move together with the trolleys, these movements generate a shift of the aircraft CG position.
These differences in aircraft configuration have to be taken into account when checking the CG position against the relevant certified CG limits, introducing an additional moment in the operational margin. Eaircraft CG movement = Real Aircraft Moment . Balance Chart Aircraft Moment Eaircraft CG movement = Moment due to item movement Item being : Flaps/Slats, Landing Gear, Revesers, Water, Passenger, Crew…
WEIGHT AND
BALANCE
WEIGHT AND
BALANCE
C. BALANCE CHART DESIGN
3.6.1. Flaps/Slats and Landing gear movements
DOW and DOCG values are published for the following configuration : . Flaps/slats in clean position
. Landing Gear extended
So on the balance chart all the aircraft
CG values correspond to this
configuration.
In reality Takeoff configuration is Flaps/slats extended, Landing configuration is Flaps/slats extended and Flight configuration is landing gear retracted.
Eaircraft CG movement = Moment due to Flaps/Slats or Landing Gears movement
The moments generated by Flaps/Slats and Landing Gears movement are published in the WBM in section 1.00.
Flaps extension moves the aircraft CG aft, Slats extension moves it forward, the total resulting moment for takeoff and landing possible configuration moves it aft so the real takeoff and landing CG will always be aft of the estimated value. So for aft certified CG operational margins determination the maximum aft movement has to be taken into account to prevent the aircraft CG being out of the limits. For the forward certified CG operational margins determination, there is no risk of being out of the limits as the operational configurations will always lead to a more aft CG than the estimated one. Nevertheless it is possible to take benefit of this situation by taking into account this CG movement is reducing the forward operational margin.
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本文链接地址：Getting to Grips with Aircraft Weight and Balance(78)
