Effect_Of_Zero_Fuel_Weight_On_Aircraft_Operations.pdf
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Operational Liaison Meeting Meeting – Fly-By-Wire Aircraft Aircraft
2004
Effect of ZFW / ZFWCG on Aircraft Operations
Customer Servi Services ces
Contents • Single-Aisle (SA) – – – –
FM Architecture FAC Computation If Incorrect ZFW entered on the MCDU If Incorrect ZFWCG entered on the MCDU
• Long-Range (LR)
. t n e m u c o d y r a t e i r p o r p d n a l a i t n e d i f n o C . d e v r e s e r s t h g i r l l A . S . A . S S U B R I A ©
– – – –
FCMC/FE Architecture CG Control If Incorrect ZFW entered on the MCDU If Incorrect ZFWCG entered on the MCDU
• Airbus Recommendations • Conclusion Effect of ZFW/ZFWCG on Aircraft Operations
Page 2
Contents • Single-Aisle (SA) – – – –
FM Architecture FAC Computation If Incorrect ZFW entered on the MCDU If Incorrect ZFWCG entered on the MCDU
• Long-Range (LR)
. t n e m u c o d y r a t e i r p o r p d n a l a i t n e d i f n o C . d e v r e s e r s t h g i r l l A . S . A . S S U B R I A ©
– – – –
FCMC/FE Architecture CG Control If Incorrect ZFW entered on the MCDU If Incorrect ZFWCG entered on the MCDU
• Airbus Recommendations • Conclusion Effect of ZFW/ZFWCG on Aircraft Operations
Page 2
Single-Aisle (SA) § § § §
FM Architecture FAC Architecture Incorrect ZFW entered on the MCDU Incorrect ZFWCG entered on the MCDU
SA: FM Architecture • The Flight Management computes the Gross Weight and the Cen Center ter of Gra Gravit vity y based on: – ZFW/ZFWCG entered by the pilot – The fuel quantity indication (from the FQI) – The fuel flow information (from the FADEC) Pilot input
FQI
FADEC
Fuel qty . t n e m u c o d y r a t e i r p o r p d n a l a i t n e d i f n o C . d e v r e s e r s t h g i r l l A . S . A . S S U B R I A ©
ZFW MCDU
ZFWCG
Effect of ZFW/ZFWCG on Aircraft Operations
FM
Fuel flow
GW CG
Page 4
SA: FM Architecture … • The GW is displayed on the ECAM. • Both the GW and CG are displayed on the MCDU’s FUEL PRED page. page .
Pilot input
FQI
FADEC
Fuel qty . t n e m u c o d y r a t e i r p o r p d n a l a i t n e d i f n o C . d e v r e s e r s t h g i r l l A . S . A . S S U B R I A ©
ZFW MCDU
ZFWCG
Effect of ZFW/ZFWCG on Aircraft Operations
FM
Fuel flow
GW CG
ECAM GW display
MCDU
GW CG
Page 5
SA: FM Architecture … • Both the GW and CG are used by the FM for predictions that include optimum managed speeds and operating speeds (Vls, Vapp, F, S and green dot )
Pilot input
FQI
FADEC
Fuel qty . t n e m u c o d y r a t e i r p o r p d n a l a i t n e d i f n o C . d e v r e s e r s t h g i r l l A . S . A . S S U B R I A ©
Fuel flow
ZFW MCDU
ZFWCG
FM
GW CG
ECAM GW display
MCDU
GW CG
Predictions/ speeds
Effect of ZFW/ZFWCG on Aircraft Operations
Page 6
SA: FAC Architecture … • On the A320, the FAC computes its own CG and GW from aerodynamic data.
• These values have a minor impact on ELAC control laws and FG control laws, as they are used to adjust the gains of the flight control laws.
• Also, the FAC computes the operating speeds . t n e m u c o d y r a t e i r p o r p d n a l a i t n e d i f n o C . d e v r e s e r s t h g i r l l A . S . A . S S U B R I A ©
(Vls, F, S, O ) that are displayed on the PFD.
Effect of ZFW/ZFWCG on Aircraft Operations
Page 7
SA: FAC Architecture … Pilot Input
FQI
EXCEPT A318
FADEC
Fuel qty
Fuel flow
ECAM
ZFW
GW ZFWCG CG Predictions/Speeds FM
MCDU
. t n e m u c o d y r a t e i r p o r p d n a l a i t n e d i f n o C . d e v r e s e r s t h g i r l l A . S . A . S S U B R I A ©
ADIRS GW, CG A/C Config Thrust THS Position
Effect of ZFW/ZFWCG on Aircraft Operations
MCDU
ELAC
Control laws
FG
Control laws
FAC Speeds
PFD
Page 8
SA: FAC Architecture… CRUISE
EXCEPT A318
15000 feet, or Speed above 250knots D E S C
B M I L C
CONF1 Selection A P P R
. t n e m u c o d y r a t e i r p o r p d n a l a i t n e d i f n o C . d e v r e s e r s t h g i r l l A . S . A . S S U B R I A ©
GW from FM
GW = f(AOA)
Effect of ZFW/ZFWCG on Aircraft Operations
GW = f(FF)
GW = GW = GW from FM f(AOA) f(FF)
Page 9
SA: If Incorrect ZFW Entered • The GW, computed by the FM and displayed on the ECAM, is incorrect. Incorrect ZFW
FADEC
FQI Fuel qty
Fuel flow
ZFW MCDU
ZFWCG
GW CG
MCDU
GW CG
Predictions/ speeds
. t n e m u c o d y r a t e i r p o r p d n a l a i t n e d i f n o C . d e v r e s e r s t h g i r l l A . S . A . S S U B R I A ©
FM
ECAM GW display
Effect of ZFW/ZFWCG on Aircraft Operations
Page 10
SA: If Incorrect ZFW Entered… The GW and CG, displayed on MCDU, are incorrect.
Incorrect ZFW
FADEC
FQI Fuel qty
Fuel flow
ZFW MCDU
ZFWCG
GW CG
MCDU
GW CG
Predictions/ speeds
. t n e m u c o d y r a t e i r p o r p d n a l a i t n e d i f n o C . d e v r e s e r s t h g i r l l A . S . A . S S U B R I A ©
FM
ECAM GW display
Effect of ZFW/ZFWCG on Aircraft Operations
Page 11
SA: If Incorrect ZFW Entered… • The FM predictions are affected. Incorrect ZFW
FADEC
FQI Fuel qty
Fuel flow
ZFW MCDU
ZFWCG
GW CG
MCDU
GW CG
Predictions / speeds
. t n e m u c o d y r a t e i r p o r p d n a l a i t n e d i f n o C . d e v r e s e r s t h g i r l l A . S . A . S S U B R I A ©
FM
ECAM GW display
Effect of ZFW/ZFWCG on Aircraft Operations
Page 12
SA: If Incorrect ZFW Entered… •A discrepancy can be observed between the operating speeds, displayed on the MCDU and those displayed on the PFD (PFD speeds are not affected (Except on the A318)). Incorrect ZFW
FADEC
FQI Fuel qty
ZFW MCDU
ZFWCG
FM
GW CG
MCDU
GW CG
Predictions / speeds
. t n e m u c o d y r a t e i r p o r p d n a l a i t n e d i f n o C . d e v r e s e r s t h g i r l l A . S . A . S S U B R I A ©
ECAM GW display
Fuel flow
ADIRS A/C Config Thrust THS Position Effect of ZFW/ZFWCG on Aircraft Operations
FAC
speeds
PFD
Page 13
SA: If Incorrect ZFW Entered … Incorrect ZFW
FADEC
FQI Fuel qty
Fuel flow
ZFW
GW FM
ZFWCG
MCDU
Predictions “CHECK GW” Message . t n e m u c o d y r a t e i r p o r p d n a l a i t n e d i f n o C . d e v r e s e r s t h g i r l l A . S . A . S S U B R I A ©
Comp.
ADIRS GW, CG A/C Config Thrust THS position
Effect of ZFW/ZFWCG on Aircraft Operations
FAC Speeds
In flight if the ZFW error is significant, ECAM GW display the « CHECK GW » message automatically ELAC Control triggers laws if the FM and FAC FG Control laws by GW differ more than 7 PFD tons. Page 14
SA: If Incorrect ZFWCG Entered • An incorrect ZFWCG has a minor impact on the predictions computed by the FM.
• There is an impact on the Vls and VApp that is displayed on the MCDU.
• On SA (except A318), there is no effect on the Vls displayed on PFD, due to the fact that, in flight, the FAC computes its own CG. . t n e m u c o d y r a t e i r p o r p d n a l a i t n e d i f n o C . d e v r e s e r s t h g i r l l A . S . A . S S U B R I A ©
Effect of ZFW/ZFWCG on Aircraft Operations
Page 15
SA: If Incorrect ZFWCG Entered … • In flight, the correct CG is not accessible: – The pilot has no access to the FAC value (It is never displayed on the ECAM). – In flight, the THS position is not representative of the current CG (depends on Mach, weight, altitude):
. t n e m u c o d y r a t e i r p o r p d n a l a i t n e d i f n o C . d e v r e s e r s t h g i r l l A . S . A . S S U B R I A ©
In flig ht, the THS pos ition does not enable the current C G to be determined. Effect of ZFW/ZFWCG on Aircraft Operations
Page 16
A318: FM and FAC Architecture • Goal of the A318 FAC Standard: To cancel speed discrepancies between the MCDU and the PFD.
4
• A318 FAC Design: The FAC uses the GW/CG, computed by the FM, only for the computation of the operating speeds that are displayed on the PFD.
4
. t n e m u c o d y r a t e i r p o r p d n a l a i t n e d i f n o C . d e v r e s e r s t h g i r l l A . S . A . S S U B R I A ©
• The rest of the FAC architecture remains unchanged. In particular, the comparison between the GW computed by the FM and FAC (CHECK GW message).
Effect of ZFW/ZFWCG on Aircraft Operations
Page 17
A318: FM and FAC Architecture … Pilot Input
FQI
A318
FADEC
Fuel qty
Fuel flow
ECAM
ZFW
GW ZFWCG CG Predictions/ Speeds FM
MCDU
GW CG
. t n e m u c o d y r a t e i r p o r p d n a l a i t n e d i f n o C . d e v r e s e r s t h g i r l l A . S . A . S S U B R I A ©
ADIRS GW, CG A/C config Thrust THS position
ELAC
Control laws
FG
Control laws
FAC
PFD FM GW/CG
Effect of ZFW/ZFWCG on Aircraft Operations
MCDU
Speeds
Page 18
A318: FM and FAC Architecture… • The rest of the FAC architecture remains unchanged.
The comparison between the GW computed by the FM and FAC still exists. (CHECK GW message)
. t n e m u c o d y r a t e i r p o r p d n a l a i t n e d i f n o C . d e v r e s e r s t h g i r l l A . S . A . S S U B R I A ©
Effect of ZFW/ZFWCG on Aircraft Operations
Page 19
A318: If Incorrect ZFW Entered • As with the A320: Same effect on FM predictions/speeds
4
• The Speeds (Vls, F, S, O) that are displayed on the PFD are impacted in the same way as on the MCDU (no longer speed discrepancies). . t n e m u c o d y r a t e i r p o r p d n a l a i t n e d i f n o C . d e v r e s e r s t h g i r l l A . S . A . S S U B R I A ©
But VaPROT, VaMAX and VSW are not affected since based on aerodynamic data.
Effect of ZFW/ZFWCG on Aircraft Operations
Page 20
A318: If Incorrect ZFW Entered… • As with the A320: If the ZFW error if significant: 4The
« CHECK GW » message automatically triggers
once, in flight, if the FM and the FAC GW differs by more than 7 tons. . t n e m u c o d y r a t e i r p o r p d n a l a i t n e d i f n o C . d e v r e s e r s t h g i r l l A . S . A . S S U B R I A ©
Effect of ZFW/ZFWCG on Aircraft Operations
Page 21
A318: If Incorrect ZFWCG Entered • As with the A320: Same effect on FM predictions / speeds.
4
• The VLS that is displayed on the PFD is impacted in the same way as on the MCDU. . t n e m u c o d y r a t e i r p o r p d n a l a i t n e d i f n o C . d e v r e s e r s t h g i r l l A . S . A . S S U B R I A ©
No PFD/MCDU discrepancy
4
But VaPROT, VaMAX and VSW are not affected since based on aerodynamic data. Effect of ZFW/ZFWCG on Aircraft Operations
Page 22
Long-Range (LR) § § § §
FCMC/FE Architecture CG Control If Incorrect ZFW entered on the MCDU If Incorrect ZFWCG entered on the MCDU
LR: FCMC/FE Architecture • The Fuel Control and Monitoring Computer (FCMC) computes the GW and CG, based on the : – Mandatory ZFW and ZFCG entered by the pilot, and – The fuel quantities gauged in each individual tank. Pilot input Gauged Pilot input fuel quantities ZFW MCDU
ZFWCG
FCMC
. t n e m u c o d y r a t e i r p o r p d n a l a i t n e d i f n o C . d e v r e s e r s t h g i r l l A . S . A . S S U B R I A ©
GW CG ZFW
MCDU
Effect of ZFW/ZFWCG on Aircraft Operations
ZFWCG
Gauged fuel quantities FCMC
GW CG
Page 24
LR: FCMC/FE Architecture … • The current GW and CG are displayed on the ECAM. • They are also displayed on the MCDU’s FUEL PRED page. • And transmitted to the Flight Envelope (FE). ECAM
Pilot input
GW/CG display Gauged Pilot input fuel quantities
ZFW MCDU
ZFWCG
FCMC
. t n e m u c o d y r a t e i r p o r p d n a l a i t n e d i f n o C . d e v r e s e r s t h g i r l l A . S . A . S S U B R I A ©
GW CG ZFW
MCDU
Effect of ZFW/ZFWCG on Aircraft Operations
ZFWCG
MCDU
Gauged fuel quantities GW FE FCMC CG
Page 25
LR: FCMC/FE Architecture … • The FE transmits the GW and CG, computed by the FCMC, to the FM, PRIM and FG, for a use similar to that of Single-Aisle aircraft. ECAM
Pilot input
GW/CG display Gauged Pilot input fuel quantities
ZFW MCDU
ZFWCG
FCMC
. t n e m u c o d y r a t e i r p o r p d n a l a i t n e d i f n o C . d e v r e s e r s t h g i r l l A . S . A . S S U B R I A ©
GW CG ZFW
MCDU
Effect of ZFW/ZFWCG on Aircraft Operations
ZFWCG
MCDU FM Gauged fuel quantitiesFG
Predictions speeds
Control laws
GW FE FCMC CG PRIM Control laws
Page 26
LR: FCMC/FE Architecture … • The GW and CG from FCMC are also used by the FE for computing the operating speeds displayed on the PFD.
ECAM
Pilot input
GW/CG display Gauged Pilot input fuel quantities
ZFW MCDU
ZFWCG
FCMC
. t n e m u c o d y r a t e i r p o r p d n a l a i t n e d i f n o C . d e v r e s e r s t h g i r l l A . S . A . S S U B R I A ©
GW CG ZFW
MCDU
ZFWCG
MCDU FM Gauged fuel quantitiesFG
Control laws
GW FE FCMC CG PRIM Control laws
PFD Effect of ZFW/ZFWCG on Aircraft Operations
Predictions speeds
Speeds Page 27
LR: CG Control • The FCMC also ensures CG control according to the •
current GW and CG, It moves the CG backwards, and maintain the AFT CG target to reduce fuel consumption in cruise. Pilot input Gauged fuel quantities ZFW MCDU
. t n e m u c o d y r a t e i r p o r p d n a l a i t n e d i f n o C . d e v r e s e r s t h g i r l l A . S . A . S S U B R I A ©
FCMC
ZFWCG
GW CG
CG regulation
Effect of ZFW/ZFWCG on Aircraft Operations
Page 28
LR: AFT CG Target WEIGHT % .5 0 t e r g t e a r g t G t a G T C C F T A F A
it m li d fi e r ti e c ft A
FCMC
§ FUEL BURN
§AUTOMATIC TRIM
. t n e m u c o d y r a t e i r p o r p d n a l a i t n e d i f n o C . d e v r e s e r s t h g i r l l A . S . A . S S U B R I A ©
TANK TRANSFER
CG Effect of ZFW/ZFWCG on Aircraft Operations
Page 29
LR: FE’s Backup GW and CG • A backup CG, along with the backup GW, are computed by the FE from aerodynamic data.
• It is used by the FM, FG and PRIMs, in case of a dual FCMC GW/CG failure. CG Speed or Mach Thrust . t n e m u c o d y r a t e i r p o r p d n a l a i t n e d i f n o C . d e v r e s e r s t h g i r l l A . S . A . S S U B R I A ©
Backup GW/CG Computation
GW
FE
Altitude THS Position
ELEVATOR Position PRIM
Effect of ZFW/ZFWCG on Aircraft Operations
Page 30
LR: EXCESS AFT CG Warning • An EXCESS AFT CG warning is also generated independently from the CG computed by FCMC, in order to limit the AFT CG.
FE
CG CG Speed or Mach Thrust . t n e m u c o d y r a t e i r p o r p d n a l a i t n e d i f n o C . d e v r e s e r s t h g i r l l A . S . A . S S U B R I A ©
Backup GW/CG Computation
GW
§ AFT CG LIMIT
FE
Altitude THS Position
GW
ELEVATOR Position PRIM
Effect of ZFW/ZFWCG on Aircraft Operations
Page 31
LR: If Incorrect ZFW Entered • The GW that is computed by the FCMC is incorrect. • The CG that is computed by the FCMC is also incorrect. ECAM
Incorrect ZFW
GW /CG display MCDU Gauged fuel quantities
ZFW
MCDU
GW CG ZFWCG CG Regulation
PREDICTION SPEEDS
FG
CONTROL LAWS
FCMC
(slightly affected) . t n e m u c o d y r a t e i r p o r p d n a l a i t n e d i f n o C . d e v r e s e r s t h g i r l l A . S . A . S S U B R I A ©
FM
FE PRIM PFD
Effect of ZFW/ZFWCG on Aircraft Operations
SPEEDS
Page 32
LR: If Incorrect ZFW Entered… The GW and CG displayed on ECAM/MCDU are incorrect.
ECAM
Incorrect ZFW
GW /CG display MCDU Gauged fuel quantities
ZFW
MCDU
GW CG ZFWCG CG Regulation
PREDICTION SPEEDS
FG
CONTROL LAWS
FCMC
(slightly affected) . t n e m u c o d y r a t e i r p o r p d n a l a i t n e d i f n o C . d e v r e s e r s t h g i r l l A . S . A . S S U B R I A ©
FM
FE PRIM PFD
Effect of ZFW/ZFWCG on Aircraft Operations
SPEEDS
Page 33
LR: If Incorrect ZFW Entered … The CG regulation is slightly affected, since the AFT CG target depends on the weight. ECAM
Incorrect ZFW
GW /CG display MCDU Gauged fuel quantities
ZFW
MCDU
GW CG ZFWCG CG Regulation
PREDICTION SPEEDS
FG
CONTROL LAWS
FCMC
(slightly affected) . t n e m u c o d y r a t e i r p o r p d n a l a i t n e d i f n o C . d e v r e s e r s t h g i r l l A . S . A . S S U B R I A ©
FM
FE PRIM
CONTROL LAWS
PFD
SPEEDS
But, the“EXCESS AFT CG” warning is not affected. Effect of ZFW/ZFWCG on Aircraft Operations
Page 34
LR: If Incorrect ZFW Entered … The incorrect GW and CG are transmitted by the FE to the FM, FG and PRIM. ECAM
Incorrect ZFW
GW /CG display MCDU Gauged fuel quantities
ZFW
MCDU
GW CG ZFWCG CG Regulation
PREDICTION SPEEDS
FG
CONTROL LAWS
FCMC
(slightly affected) . t n e m u c o d y r a t e i r p o r p d n a l a i t n e d i f n o C . d e v r e s e r s t h g i r l l A . S . A . S S U B R I A ©
FM
Effect of ZFW/ZFWCG on Aircraft Operations
FE PRIM
CONTROL LAWS
PFD
SPEEDS
Page 35
LR: If Incorrect ZFW Entered … The FM predictions/speeds will be affected … ECAM
Incorrect ZFW
GW /CG display MCDU Gauged fuel quantities
ZFW
MCDU
GW CG ZFWCG CG Regulation
PREDICTION SPEEDS
FG
CONTROL LAWS
FCMC
(slightly affected) . t n e m u c o d y r a t e i r p o r p d n a l a i t n e d i f n o C . d e v r e s e r s t h g i r l l A . S . A . S S U B R I A ©
FM
Effect of ZFW/ZFWCG on Aircraft Operations
FE PRIM
CONTROL LAWS
PFD
SPEEDS
Page 36
LR: If Incorrect ZFW Entered … The FG and PRIM control laws are slightly affected.
ECAM
Incorrect ZFW
GW /CG display MCDU Gauged fuel quantities
ZFW
MCDU
GW CG ZFWCG CG Regulation
PREDICTION SPEEDS
FG
CONTROL LAWS
FCMC
(slightly affected) . t n e m u c o d y r a t e i r p o r p d n a l a i t n e d i f n o C . d e v r e s e r s t h g i r l l A . S . A . S S U B R I A ©
FM
(slightly affected)
FE
PRIM
CONTROL LAWS
(slightly affected)
PFD
Effect of ZFW/ZFWCG on Aircraft Operations
SPEEDS
Page 37
LR: If Incorrect ZFW Entered … Vls, F, S, and green dot displayed on the PFD are affected. ECAM
Incorrect ZFW
GW /CG display MCDU Gauged fuel quantities
ZFW
MCDU
GW CG ZFWCG CG Regulation
PREDICTION SPEEDS
FG
CONTROL LAWS
FCMC
(slightly affected) . t n e m u c o d y r a t e i r p o r p d n a l a i t n e d i f n o C . d e v r e s e r s t h g i r l l A . S . A . S S U B R I A ©
FM
(slightly affected)
FE
PRIM
CONTROL LAWS
(slightly affected)
PFD
Effect of ZFW/ZFWCG on Aircraft Operations
SPEEDS
Page 38
LR: If Incorrect ZFW Entered … Vls, F, S, and green dot displayed on the PFD are affected. ECAM
Incorrect ZFW
GW /CG display MCDU Gauged fuel quantities
ZFW
MCDU
GW CG ZFWCG CG Regulation
PREDICTION SPEEDS
FG
CONTROL LAWS
FCMC
(slightly affected) . t n e m u c o d y r a t e i r p o r p d n a l a i t n e d i f n o C . d e v r e s e r s t h g i r l l A . S . A . S S U B R I A ©
FM
(slightly affected)
FE
PRIM
CONTROL LAWS
(slightly affected)
PFD
SPEEDS
But VaPROT, VaMAX and VSW are not affected since based on aerodynamic data. Effect of ZFW/ZFWCG on Aircraft Operations
Page 39
LR: If Incorrect ZFWCG Entered The CG computed by the FCMC is incorrect. ECAM
Incorrect ZFWCG
GW/CG display MCDU
Gauged fuel quantities ZFW
MCDU
GW CG ZFWCG CG Regulation
FM
PREDICTION SPEEDS
FG
CONTROL LAWS
FCMC
FE . t n e m u c o d y r a t e i r p o r p d n a l a i t n e d i f n o C . d e v r e s e r s t h g i r l l A . S . A . S S U B R I A ©
Effect of ZFW/ZFWCG on Aircraft Operations
PRIM
CONTROL LAWS
PFD
SPEEDS
Page 40
LR: If Incorrect ZFWCG Entered … Incorrect CG is displayed on the ECAM / MCDU. ECAM
Incorrect ZFWCG
GW/CG display MCDU
Gauged fuel quantities ZFW
MCDU
GW CG ZFWCG CG Regulation
FM
PREDICTION SPEEDS
FG
CONTROL LAWS
FCMC
FE . t n e m u c o d y r a t e i r p o r p d n a l a i t n e d i f n o C . d e v r e s e r s t h g i r l l A . S . A . S S U B R I A ©
Effect of ZFW/ZFWCG on Aircraft Operations
PRIM
CONTROL LAWS
PFD
SPEEDS
Page 41
LR: If Incorrect ZFWCG Entered … CG regulation may be affected.
ECAM
Incorrect ZFWCG
GW/CG display MCDU
Gauged fuel quantities ZFW
MCDU
GW CG ZFWCG CG Regulation
FM
PREDICTION SPEEDS
FG
CONTROL LAWS
FCMC
FE . t n e m u c o d y r a t e i r p o r p d n a l a i t n e d i f n o C . d e v r e s e r s t h g i r l l A . S . A . S S U B R I A ©
PRIM
CONTROL LAWS
PFD
SPEEDS
But the“EXCESS AFT CG” warning is not affected Effect of ZFW/ZFWCG on Aircraft Operations
Page 42
LR: If Incorrect ZFWCG Entered … The incorrect CG is transmitted by the FE to the FM, FG, PRIM and PFD. ECAM
Incorrect ZFWCG
GW/CG display MCDU
Gauged fuel quantities ZFW
MCDU
GW CG ZFWCG CG Regulation
FM
PREDICTION SPEEDS
FG
CONTROL LAWS
FCMC
FE . t n e m u c o d y r a t e i r p o r p d n a l a i t n e d i f n o C . d e v r e s e r s t h g i r l l A . S . A . S S U B R I A ©
Effect of ZFW/ZFWCG on Aircraft Operations
PRIM
CONTROL LAWS
PFD
SPEEDS
Page 43
LR: If Incorrect ZFWCG Entered … FM Predictions and speeds will be impacted.. ECAM
Incorrect ZFWCG
GW/CG display MCDU
Gauged fuel quantities ZFW
MCDU
GW CG ZFWCG CG Regulation
FM
PREDICTION SPEEDS
FG
CONTROL LAWS
FCMC
FE . t n e m u c o d y r a t e i r p o r p d n a l a i t n e d i f n o C . d e v r e s e r s t h g i r l l A . S . A . S S U B R I A ©
Effect of ZFW/ZFWCG on Aircraft Operations
PRIM
CONTROL LAWS
PFD
SPEEDS
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LR: If Incorrect ZFWCG Entered … • FG and PRIM control laws are slightly affected. • VLS displayed on PFD is impacted . ECAM
Incorrect ZFWCG
GW/CG display MCDU
Gauged fuel quantities ZFW
MCDU
GW CG ZFWCG CG Regulation
FM
PREDICTION SPEEDS
FG
CONTROL LAWS
FCMC
(slightly affected)
FE . t n e m u c o d y r a t e i r p o r p d n a l a i t n e d i f n o C . d e v r e s e r s t h g i r l l A . S . A . S S U B R I A ©
PRIM
CONTROL LAWS
(slightly affected)
PFD
SPEEDS (VLS only)
But VaPROT, VaMAX and VSW are not affected since based on aerodynamic data. Effect of ZFW/ZFWCG on Aircraft Operations
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LR: If Incorrect ZFWCG Entered … • As with SA aircraft, the correct CG is not accessible: – The pilot has no access to the FE value (It is never displayed on the ECAM). – In flight, the THS position is not representative of the current CG (depends on Mach, weight, altitude):
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In flig ht, the THS pos ition does not enable the CG to be determined.
Effect of ZFW/ZFWCG on Aircraft Operations
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Airbus Recommendations
Airbus Recommendations FLIGHT PREPARATION
• LTS ZFW and ZFCG must be computed CAREFULLY. • Incorrect ZFW and ZFWCG computation: May significantly affect predictions and speeds…
4
May significantly affect V1, V2, and VR computation.
4
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The only way for the crew to check ZFW, ZFCG, V1, V2, VR is EXPERIENCE…
Effect of ZFW/ZFWCG on Aircraft Operations
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Airbus Recommendations… Cockpit Preparation (All FBW)
• ZFW and ZFCG must be entered/ checked CAREFULLY…
LR FCOM 3.03.06
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Effect of ZFW/ZFWCG on Aircraft Operations
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Airbus Recommendations … Before Pushback, or Start, when the final LTS is available (All FBW):
• Check the final ZFW / ZFCG with the previously-entered data (FCOM 3.03.07)
• Always check that TOCG is within the LTS operational limits, not the certified limits: . t n e m u c o d y r a t e i r p o r p d n a l a i t n e d i f n o C . d e v r e s e r s t h g i r l l A . S . A . S S U B R I A ©
The Operational limits include tolerance on cargo loading and passenger distribution
4
The certified limits take no margin.
4
Effect of ZFW/ZFWCG on Aircraft Operations
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Airbus Recommendations … • For the A330/A340 A discrepancy between the LTS CG and the ECAM CG may occur since:
4
–
The LTS Fuel distribution is based on standard refuel distribution.
– Manual refueling with non standard distribution may . t n e m u c o d y r a t e i r p o r p d n a l a i t n e d i f n o C . d e v r e s e r s t h g i r l l A . S . A . S S U B R I A ©
inadvertently be performed.
Effect of ZFW/ZFWCG on Aircraft Operations
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Airbus Recommendations … • For the A330/A340 … In case of a greater than 2% discrepancy between the final LTS CG and the ECAM CG: 4
4 . t n e m u c o d y r a t e i r p o r p d n a l a i t n e d i f n o C . d e v r e s e r s t h g i r l l A . S . A . S S U B R I A ©
4
Check that the ZFW / ZFCG have been entered correctly. If the discrepancy remains, rely on the ECAM CG. BUT, check that it is within the LTS operational limits (not the certified limits). The ECAM CG can also be crosschecked by using the LPC weight and balance module or the FCOM 2 .01.40.
Effect of ZFW/ZFWCG on Aircraft Operations
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Airbus Recommendations …
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Effect of ZFW/ZFWCG on Aircraft Operations
AIRBUS LPC
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Airbus Recommendations … • For the A330/A340 … In case of a less than 2% discrepancy between the final LTS CG and the ECAM CG:
4
–No further action is required.
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–BUT, nevertheless, always check that the ECAM CG is within the the LTS operational limits.
Effect of ZFW/ZFWCG on Aircraft Operations
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Conclusion • Predictions and speed computations are impacted by ZFW/ZFWCG. è On ground: Ø LTS ZFW/ZFWCG should be carefully computed. Ø The crew should carefully check these values and that TOCG is within the operational limits.
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è However, in flight: Ø GW/CG is also computed independently from these values: – a GW crosscheck is available in flight (SA family) – a CG crosscheck is available in flight (LR family) Ø
Protection speeds are not impacted by ZFW and ZFCG entered by the crew.
Effect of ZFW/ZFWCG on Aircraft Operations
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