D.
The system detects faults as follows:
(1)
The system initiates a self-test following each power up. A WARN ELEX message is displayed on EICAS whenever a fault is detected.
(2)
The BITE detects and displays internal faults and interface faults as alphanumeric codes on the Warning Electronic Unit (WEU) BITE Module.
E.
The stall warning system monitors data inputs from the following systems to perform its functions (Fig. 1):
(1)
Airplane Mach, true air speed, computed airspeed, and indicated angle of attack from Air Data Computers (ADC) (Ref 34-12-00).
(2)
LE slat position from Flap/Slat Electronic Units (FSEU) (Ref 27-51-00).
(3)
TE flap position from Flap/Slat Electronic Units (FSEU) (Ref 27-51-00).
(4)
Airplane pitch angle and pitch rate from Inertial Reference System (IRS) (AMM 34-22-00).
(5)
Power from the WEU power supply modules (AMM 31-51-00).
(6)
Air/Ground Mode from Air/ground relay system (Ref 32-09-00).
F.
The stall warning system includes the following components:
(1)
Left and right stick shakers
(2)
Left and right Stall Warning Computers (SWC's)
(3)
Left and right STALL test switches
(4)
WEU BITE module
2. Component Details_________________
A. Stick Shakers (Fig. 2)
(1) The left and right stick shakers are 28v dc motor-driven vibrating devices attached to the forward side of each control column.
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AIR/GROUND
SIGNAL
SLAT AND
FLAP POSITION
SIGNALS
L
STALL TEST
SWITCH
ADC DATA
AIR/GROUND
SIGNAL
SLAT AND
FLAP POSITION
SIGNALS
R
STALL TEST
SWITCH
ADC DATA
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MAINTENANCE MANUAL
WARNING
AND
INDICATION
CAPTAIN'S
STICK
SHAKER
F/O
STICK
SHAKER
WARNING
AND
INDICATION
Stall Warning System Introduction
Figure 1
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MAINTENANCE MANUAL
A
Control Column Shaker
Figure 2
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(2)
Each stick shaker is activated by its SWC to shake the control column to warn the flight crew of an impending stall. The left stick shaker is controlled by the left SWC and the right stick shaker by the right SWC.
(3)
The stick shakers are activated on the ground for test purposes using the STALL L/R test switches.
(4)
The stick shakers are located in the flight compartment.
B.
Stall Warning Computer (SWC) (Fig. 3)
(1)
The two Stall Warning Computers are located in the Warning Electronics Unit (WEU) P51.
(2)
Each SWC is powered by the Warning Electronic Unit power supply modules. Each SWC monitors inputs from the ADC, FSEU, IRS, and air/ground relays.
(3)
When an impending stall conditions is detected, the stall warning computers activate the stick shakers and extend the slats if the flaps are in the takeoff position. The SWC's provide inputs to the GPWC and EFIS to provide the flight crew with visual and aural warnings and guidance in windshear conditions.
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