*
Nose gear down and locked from the proximity switch electronic unit (PSEU)

*
Speedbrake lever position (SBLP) from the primary flight computers (PFCs)

*
Flap and slat position from the flap/slat electronics units (FSEUs).

The WEUs compare the AOA STRIP and the AOA. If the AOA is equal to or higher than the AOA STRIP, each WEU channel makes a stick shaker actuator enable signal. This will happen only if the airplane is in the air.
The stick shaker actuators come on only when at least two channels in the same WEU make a stick shaker actuator enable signal.
Icing Correction
Selection of wing or engine anti-ice during flight will cause the stick shaker angle of attack schedule to be adjusted downward. The result is the stick shaker will activate at a higher speed.
Air Mode
The WEUs make the stick shaker actuators come on only when the air mode signal is true. The WEUs use these inputs to calculate the air mode signal:
*
Angle of attack (AOA)

*
Computed airspeed

*
Pitch angle.

All these signals come from the ADIRU. If the ADIRU fails, the WEUs use the SAARU.
EFFECTIVITY BEJ ALL  31-51-00 
Page 98.6 
D633W101-BEJ  Jan 05/2004 

777 AIRCRAFT MAINTENANCE MANUAL

WES -STALL WARNING FUNCTION

EFFECTIVITY BEJ ALL  31-51-00 
Page 98.7 
D633W101-BEJ  Jan 05/2003 

777 AIRCRAFT MAINTENANCE MANUAL

THIS PAGE IS INTENTIONALLY LEFT BLANK

31-51-00

Page 98.8 D633W101-BEJ Jan 05/2003

WES -PITCH LIMIT INDICATION

General
The WEUs calculate and show the flight crew the maximum pitch limit. The maximum pitch limit is the number of degrees the airplane can pitch up from the current pitch angle before the stick shaker actuators come on.
PLI Logic
The pitch limit indication (PLI) logic in each WEU channel uses these inputs to calculate the maximum pitch limit:
*
Active control minimum speed (VCMIN) -VCMIN comes from the flight management computing function (FMCF) of AIMS

*
Stick shaker speed (VSS) -VSS comes from the VSS logic in each WEU

*
Stick shaker trip point

*
Corrected angle of attack (AOA)

*
Air mode signal

*
Computed airspeed (VCAS)

*
Flaps up -This signal comes from the flap slat electronics units (FSEUs)

*
Leading edge devices retracted -This signal comes from the FSEUs.

PLI Data
The PLI logic sends the PLI data to the AIMS cabinets. The AIMS cabinets send the data to the primary flight displays (PFDs). The PFDs show the pitch limit indicator symbol.
EFFECTIVITY
BEJ ALL

The WEUs send valid PLI data to the AIMS for both flaps not up and flaps up conditions.
For flaps not up conditions, the WEUs always send valid PLI data to the AIMS.
For flaps up conditions, the WEUs send valid PLI data to the AIMS only when any of these conditions is present:
*
The flaps are up

*
VCAS is less than the upper limit of the FMCF minimum maneuver speed (amber band) on the PFD speed tape

*
VCAS is less than 1.14 VSS.

At any other time, the data is no computed data (NCD).
The PLI goes out of view for any of these conditions:
*
VCAS is 5 knots above the upper limit of the FMCF minimum maneuver speed (amber band) for more than 15 seconds

*
VCAS is above 1.14 VSS.

Pitch Limit Indications
When the airplane is on the ground and the flaps are not up, the pitch limit indicator shows 15 degrees pitch up attitude.
The maximum pitch limit indication at any time is 30 degrees minus the actual pitch angle.
31-51-00

Page 98.9 D633W101-BEJ Jan 05/2003

WES -PITCH LIMIT INDICATION
The stick shaker actuators come on when the airplane symbol reaches the same pitch as the pitch limit indicator symbol.
EFFECTIVITY BEJ ALL  31-51-00 
Page 98.10 
D633W101-BEJ  Jan 05/2003 

777 AIRCRAFT MAINTENANCE MANUAL

WES -PITCH LIMIT INDICATION

EFFECTIVITY BEJ ALL  31-51-00 
Page 98.11 
D633W101-BEJ  Jan 05/2003 

WES -SPEED TAPE PARAMETER CALCULATION -1

General
The WEUs use proximity switch electronic unit (PSEU) data to make these signals:
*
All gear up and locked

*
Nose gear not compressed signal

*
Nose gear down and locked.

The WEUs use those signals to make speed tape parameters.
EFFECTIVITY BEJ ALL  31-51-00 
Page 98.12 
D633W101-BEJ  Jan 05/2003 

777 AIRCRAFT MAINTENANCE MANUAL
　
中國航空網 m.k6050.com
航空翻譯 www.aviation.cn
本文鏈接地址：777 AMM 飛機維護手冊 指示和記錄系統 2(7)