Note: • The FE computes a backup:
‐ GW, with aerodynamic data or from Fuel Used (FU) data
‐ CG, with aerodynamic data, and the THS position.
If FCMC data are available, the GW and CG FCMC computed are used. If FCMC data are not available, the GW and CG FE computed are used.
However, if the FCMC-computed CG, and the FE-computed CG differs more than a specified threshold, the PRIM uses 30 % CG for flight control laws.
? The FE uses VS1G from the PRIM to compute characteristic speeds (VLS , F, S, GD). These speeds are displayed on PFD.
? For the calculation of ValphaPROT, ValphaMAX, and VSW, the PRIM uses AOA data only.
4. The FE-computed CG is used to trigger the Excess AFT CG warnings of the FWC. This works independently from the FCMC.
GW and CG computation and use
ENTRY ERROR AND OPERATIONAL CONSEQUENCES
Applicable to: ALL
The following summarizes the impact of erroneous ZFW or ZFWCG entries on the INIT B page of the MCDU:
ERRONEOUS ZFWCG ENTRY
If the ZFWCG entry is not correct, the FCMC-computed CG will not be correct, and:
? An erroneous CG appears on both the SD page of the ECAM, and on the FUEL PRED page of the MCDU.
? Affects CG regulation.
However, the EXCESS AFT CG warning remains reliable.
SUPPLEMENTARY INFORMATION
ZFW - ZFCG ENTRY ERRORS
? Slightly affects FM predictions.
? Impacts the VLS and VAPP speeds, that appear on the PERF APPR page of the MCDU (A340-500/600 only).
? The pitch trim setting may not be correct at takeoff.
? The PRIM operates with a CG of 30 % in flight.
However, this will have a very small effect on aircraft handling.
? Slightly affects AP/FD control laws.
? Impacts the VLS that appears on the PFD (A340-500/600 only).
However, ValphaPROT, ValphaMAX, VSW are not affected, because they are calculated on the basis of aerodynamic data.
ERRONEOUS ZFW ENTRY
If the ZFW entry is not correct, the FCMC-computed GW and, to a lesser degree, the CG will not be correct, and:
? Erroneous GW and CG appear on both the ECAM and on the FUEL PRED page of the MCDU.
? Slightly affects CG regulation, because the aft CG target depends on the weight. However the EXCESS AFT CG warning remains reliable.
? May affect the SRS guidance mode (If VLS is greater than the V2 that is entered on the PERF TO page of the MCDU).
? Affects FM predictions and speeds.
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本文鏈接地址：A330/A340 機組訓練手冊 FCTM Flight Crew Training Manual 2(69)
