BK-737FSL-301R1-AP-1of2-82900 (Recuperado) (Recuperado 1).pdf

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737-600/700/800/900 TRAINING MANUAL
ALTEON PROPRIETARY. Copyright. See title page for details
THIS PAGE INTENTIONALLY LEFT BLANK
YAW DAMPER SYSTEM -- INTRODUCTION
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Purpose
The yaw damper system keeps the airplane stable around
the airplane yaw (vertical) axis. During flight, the
yaw damper commands rudder movement in proportion to
and opposite to the airplane yaw moment. This keeps
unwanted yaw motion to a minimum and makes the flight
smoother.
Unwanted airplane yaw motion is caused by either of the
following conditions:
- Dutch roll
- Air turbulence.
Abbreviations and Acronyms
AC - alternating current
ADR - air data reference
ADIRU - air data inertial reference unit
AOA - angle of attack
ARINC - Aeronautical Radio Incorporated
ASIC - application specific integrated circuit
ATR - Austin Trumbull Radio
BITE - built in test equipment
CAA - Civil Aviation Authority
CDS - common display system
CDU - control display unit (FMC)
CPC - cabin pressure controller
CPU - central processing unit
DC - direct current
DEU - display electronic unit
DFCS - digital flight control system
EHSV - electro-hydraulic servo valve
FAA - Federal Aviation Administration
FCC - flight control computer
FMC - flight management computer
FMCS - flight management computer system
FMS - flight management system
FSEU - flap slat electronic unit
GPWC - ground proximity warning computer
GPWS - ground proximity warning system
IR - inertial reference
I/O - input/output
LRU - line replaceable unit
LVDT - linear variable differential transformer
MCP - mode control panel
N1 - engine low pressure rotor (fan) speed
N2 - engine high pressure rotor speed
NN - a number from 01 to 99
PCU - power control unit
PFD - primary flight display
PLI - pitch limit indication
PSEU - proximity sensor electronic unit
SMYD - stall management yaw damper
SWS - stall warning system
TAI - thermal anti-ice
V - volts
Vmin - minimum safe airspeed
Vmax - maximum safe design airspeed
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WTRIS - wheel to rudder interconnect system
YDS - yaw damper system
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YAW DAMPER SYSTEM - INTRODUCTION
UNWANTED YAW MOTION DUE TO DUTCH ROLL OR TURBULENCE
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YDS -- GENERAL DESCRIPTION
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General
The yaw damper system is an autoflight system that
moves the rudder to decrease airplane yaw movement
caused by dutch roll or turbulence. The system operates
for all phases of flight and normally engages on the
ground before takeoff.
These are the components for primary yaw damping:
- SMYD 1
- Yaw damper engage switch
- Yaw damper disengage light
- Yaw damper indicator
- Yaw damper components on the main rudder PCU.
Yaw Damper Engage Switch and Disengage Light
You engage the yaw damper system with a switch on the
flight control panel. For primary yaw damping, system B
hydraulic pressure is necessary, and the FLT CTRL B
switch must be ON. The yaw damper disengage warning
light is above the engage switch. For normal yaw damper
operation, the light is off. The light comes on to show
the yaw damper is not engaged while power is on the
airplane.
Yaw Damper Indicator
The yaw damper indicator shows rudder movement because
of SMYD 1 primary yaw damping commands. The indicator
does not show rudder movement because of rudder pedal
inputs. The indicator connects only to SMYD 1.
Main Rudder PCU
There are 2 rudder PCUs, a main and a standby, in the
vertical stabilizer. These PCUs are hydraulic actuators
that move the rudder in relation to pilot rudder pedal
inputs. The main rudder PCU is used only during normal
operations. The standby rudder PCU is used only during
standby operations.
The primary yaw damper uses the main rudder PCU to move
the rudder to decrease yaw. For yaw damping, these are
the components on the main rudder PCU:
- Yaw damper solenoid valve
- Yaw damper electro-hydraulic servo valve (EHSV)
- Yaw damper LVDT
- Yaw damper actuator.
ADIRU
The air data inertial reference units (ADIRUs) send
this inertial and air data to the SMYDs:
- Airspeed
- Attitude
- Yaw and roll rates
- Accelerations.
SMYD 1 uses this data for detection of yaw movement.
The SMYD then calculates a command to move the rudder
in the opposite direction. This decreases unwanted yaw
movement of the airplane.
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FMC
The FMC gives airplane gross weight to the SMYDs for
yaw damping calculations.
Trailing Edge Flaps Up Limit Switch
The trailing edge flaps up limit switches send data to
the SMYDs to put a limit on rudder movement for yaw
damping when the flaps are up.
SMYD
The 2 SMYDs are the same. When a SMYD LRU is in position
1, it does the primary yaw damper function during
normal operations.
For primary yaw damping, the 2 SMYDs must be in
operation. This is because SMYD 1 compares its yaw
damping calculations with SMYD 2 before it gives a
rudder movement command.
For operation of the WTRIS and standby yaw damping
systems, refer to the wheel-to-rudder section.
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YAW DAMPER
ADIRU (2)
SMYD 1
RUDDER
INDICATOR
FMC
LEFT AOA SENSOR
TE FLAPS UP LIMIT SWITCHES
SMYD 2
YDS - GENERAL DESCRIPTION
MAIN RUDDER PCU
FLIGHT CONTROL PANEL
IN VERTICAL STABILIZER
ON
OFF
a
DAMPER
YAW
YAW DAMPER
STANDBY HYD
RUD
RUD
STBY STBY
B ON
OFF
A ON
OFF
A B
FLT CONTROL
ON
OFF
a
a
a
a
DIFF
FAIL
SPEED TRIM
FAIL
MACH TRIM
FAIL
AUTO SLAT
FEEL
ON
OFF
SPOILER
B
A
OFF
UP
OFF
ARM
DOWN
ALTERNATE FLAPS
a
LOW
PRESSURE
a
LOW
PRESSURE
a
LOW
PRESSURE
a
LOW
QUANTITY
STBY
RUD ON
a
PRESS
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Engage Switch and Disengage Light
The yaw damper engage switch and the disengage light
are on the flight control panel (P5 forward overhead).
The yaw damper indicator is on the P2 panel.
YDS -- FLIGHT COMPARTMENT COMPONENT LOCATION
YDS -- FLIGHT COMPARTMENT COMPONENT LOCATION
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ON
OFF
a
DAMPER
YAW
YAW DAMPER
RUD
RUD
STBY STBY
B ON
OFF
A ON
OFF
A B
FLT CONTROL
ON
OFF
a
a
a
a
DIFF
FAIL
SPEED TRIM
FAIL
MACH TRIM
FAIL
AUTO SLAT
FEEL
ON
OFF
SPOILER
B
A
OFF
UP
OFF
ARM
DOWN
ALTERNATE FLAPS
a
LOW
PRESSURE
a
LOW
PRESSURE
a
LOW
PRESSURE
STANDBY HYD
a
LOW
QUANTITY
STBY
RUD ON
a
PRESS
YDS - FLIGHT COMPARTMENT COMPONENT LOCATION
YAW DAMPER
YAW DAMPER
DISENGAGE LIGHT
ENGAGE SWITCH
YAW DAMPER INDICATOR
YAW DAMPER
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Stall Management Yaw Damper
SMYD 1 and 2 are on the E3-2 shelf in the electronic
equipment compartment. They are both passively cooled.
YDS -- ELECTRONIC EQUIPMENT COMPARTMENT COMPONENT LOCATION
YDS -- ELECTRONIC EQUIPMENT COMPARTMENT COMPONENT LOCATION
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YDS - ELECTRONIC EQUIPMENT COMPARTMENT COMPONENT LOCATION
ELECTRICAL EQUIPMENT COMPARTMENT
(LOOKING AFT)
E3-2 SHELF
- SMYD 1
- SMYD 2
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Yaw Damper Components in Vertical Stabilizer
These yaw damper components are on the main rudder PCU
in the vertical stabilizer.
- Yaw damper electro-hydraulic servo valve (EHSV)
- Yaw damper actuator
- Linear variable differential transformer (LVDT).
The yaw damper actuator and the LVDT are not line
replaceable.
Access to these yaw damper components is from an access
panel on the right side of the vertical stabilizer.
YDS -- VERTICAL STABILIZER COMPONENT LOCATION
YDS -- VERTICAL STABILIZER COMPONENT LOCATION
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YDS - VERTICAL STABILIZER COMPONENT LOCATION
ELECTRO-HYDRAULIC
SERVO VALVE
SOLENOID VALVE
LVDT (NOT SHOWN)
MAIN RUDDER PCU
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YDS -- INTERFACES
YDS -- INTERFACES
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YDS -- INTERFACES
Power Interface
Primary power for SMYD 1 is 28v dc from electrical bus
1. 28v ac from transfer bus 1 is supplied to both SMYD
1 and the yaw damper LVDT on the main rudder PCU.
The yaw damper indicator uses 115v ac from transfer
bus 1.
Digital Data
For the yaw damping function, SMYD 1 gets digital data
from the following systems:
- Air data inertial reference systems (ADIRS)
- DFCS mode control panel (MCP)
- Flight management computer system (FMCS)
- SMYD 2.
ADIRU 1 provides this air data:
- True airspeed
- Computed airspeed
- Mach number
- Baro corrected altitude
- Impact pressure.
ADIRUs 1 and 2 provide this inertial data:
- Lateral acceleration
- Roll angle
- Roll rate
- Yaw rate.
The DFCS MCP sends engage status information for FCC A
and FCC B.
The FMCS provides airplane gross weight data.
SMYD 2 supplies command data from its yaw damper
function. If the two commands are different, the
primary yaw damper will disengage.
Analog Signals
SMYD 1 supplies 28v dc to the solenoid valve on the
main rudder PCU. This enables the primary yaw damper
function. SMYD 1 then calculates and sends yaw damper
commands to the electrohydraulic servo valve (EHSV).
The LVDT on the main rudder PCU sends rudder position
feedback data to the SMYD. It also sends position data
to the yaw damper indicator.
The trailing edge flaps up limit switch sends flap
position data to SMYD 1. The SMYD uses this data during
yaw damping to limit rudder movement dependent on the
flaps being in the up position or the not up position.
The left AOA sensor sends airplane angle of attack data
to SMYD 1.
SMYD 1 also supplies 28v dc to the yaw damper engage
switch on the P5 flight control panel. This is to hold
the switch in the ON position when the yaw damper is
engaged. A ground discrete is sent to turn on the yaw
damper annunciator whenever the yaw damper is
disengaged.
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YDS -- INTERFACES
The yaw damper disengage light receives power from the
Master Dim & Test system.
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YDS - INTERFACES
L ADIRU
R ADIRU
SMYD 1
MAIN RUDDER PCU
YAW DAMPER
TRAILING EDGE FLAPS
INDICATOR
28V DC
BUS 1
YAW DAMPER
MASTER DIM
28/16V DC
UP SWITCH S245
LVDT
EHSV
SOLENOID
LEFT AOA SENSOR
28V AC
YAW DAMPER
115V AC
YAW DAMPER
XFER BUS 1
XFER BUS 1
SMYD 2
P18 CIRCUIT BREAKER
PANEL
NOTE: THIS DIAGRAM SHOWS ONLY INTERFACES FOR PRIMARY YAW DAMPING
YD DISENGAGE LIGHT
ENGAGE SWITCH
AD 4
IR 2
IR 3
& TEST
A A
VALVE
UP
FMC 1
FMC 2
DFCS MCP
MCP 3
TRANSFER RELAY
FMC 01
FMC 01
ENGAGE POWER
COMMAND SIGNALS
ENGAGE SIGNAL
ENGAGE ENABLE HI
POSITION
ENGAGE ENABLE LO
28V DC POWER
ENGAGE COMMAND
FEEDBACK
PRIMARY
POWER
FLAPS UP/NOT UP
ANGLE OF ATTACK
X-CHANNEL
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Purpose
The yaw damper solenoid valve on the main rudder PCU
pressurizes the yaw damper system. When you engage the
yaw damper system, the solenoid valve sends hydraulic
fluid to the electro-hydraulic servo valve (EHSV) that
controls the yaw damper actuator on the main rudder
PCU. This moves the rudder for yaw damping.
Physical Description
These are the three hydraulic ports in the solenoid:
- Input pressure port for input hydraulic pressure
- Output port for the output to the EHSV and yaw
damper actuator
- Return port for hydraulic fluid to the reservoir.
An electrical connector connects the solenoid valve to
the SMYD computer.
Functional Description
When the yaw damper is engaged, the SMYD sends 28v dc
to energize the solenoid valve which ports hydraulic
fluid under pressure to the EHSV and yaw damper
actuator.
YDS -- MAIN RUDDER PCU ACTUATOR - SOLENOID VALVE
YDS -- MAIN RUDDER PCU ACTUATOR - SOLENOID VALVE
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YDS - MAIN RUDDER PCU ACTUATOR - SOLENOID VALVE
ELECTRICAL CONNECTOR
RETURN PORT
HYDRAULIC OUTPUT PORT
INPUT PRESSURE PORT
INTERNAL
SUMMING LEVER
YAW DAMPER
LVDT
ACTUATOR
YAW DAMPER
SYSTEM B
VALVE B
CONTROL
SUMMING LVR
INTERNAL
HYDRAULICS
VALVE A
CONTROL
SOLENOID VALVE
YAW DAMPER
EHSV
YAW DAMPER
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Purpose
For primary yaw damping, the electrohydraulic servo
valve (EHSV) on the main rudder PCU changes an
electrical command signal from SMYD 1 into a controlled
hydraulic flow to the yaw damper actuator on the main
rudder PCU. The EHSV controls the rate and direction of
the yaw damper actuator motion for rudder movement to
provide primary yaw damping.
These are the four hydraulic ports on the EHSV:
- Input port for jet pipe controller/control spool
- Return port
- Two output ports to the yaw damper actuator.
A four pin electrical connector the SMYD computer to
the EHSV.
Functional Description
When an electrical signal for yaw damping comes from
the SMYD computer, it moves a jet pipe in the EHSV.
This causes the pressure at each end of the control
spool to change. This pressure differential causes the
control spool to move, which changes the output
pressure in each of the two output ports. This change
in the output pressure directs hydraulic fluid under
pressure to move the yaw damper actuator in the desired
direction for yaw damping.
YDS -- MAIN RUDDER PCU - ELECTROHYDRAULIC SERVO VALVE
YDS -- MAIN RUDDER PCU - ELECTROHYDRAULIC SERVO VALVE
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YDS - MAIN RUDDER PCU - ELECTROHYDRAULIC SERVO VALVE
ELECTRICAL CONNECTOR
INPUT PRESSURE PORT
RETURN PORT
OUTPUT PORTS TO
YAW DAMPER ACTUATOR
INTERNAL
SUMMING LEVER
YAW DAMPER
LVDT
ACTUATOR
YAW DAMPER
SYSTEM B
VALVE B
CONTROL
SUMMING LVR
INTERNAL
HYDRAULICS
VALVE A
CONTROL
SOLENOID VALVE
YAW DAMPER
EHSV
YAW DAMPER
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Purpose
The stall management yaw damper (SMYD) uses inertial
data from the ADIRU and other data from airplane
sensors to detect unwanted airplane yaw motion caused
by dutch roll and turbulence. The SMYD sends commands
to the main rudder PCU to move the rudder to reduce
unwanted yaw.
The SMYD weighs 10 lbs. It uses 10 watts of power. It
has these features on the front of the unit:
- Standard Boeing BITE module
- Bite instructions on the label
- BITE display
- BITE keypad.
Bite Instructions
Bite instructions on the front of the SMYD LRU describe
how to do a test of the unit and use the BITE software.
For more information on BITE, see the section on BITE
Operation later in this section.
Display
The SMYD BITE module has a two line amber display. Each
line has eight alphanumeric characters. The display
shows messages about the type of fault, maintenance
message number, and fault details. For SMYD 1, the BITE
interfaces with the stall management functions and
primary yaw damping functions and provides fault data
for these functions.
Keypad
You use the keypad to operate the SMYD BITE. The keypad
has these keys:
- ON/OFF key to turn ON the BITE
- MENU key to go to the main and previous menu pages
- UP arrow key for previous page selection in a menu
- DOWN arrow key for next page selection in a menu
- YES key to answer questions
- NO key to answer questions.
YDS -- STALL MANAGEMENT YAW DAMPER
YDS -- STALL MANAGEMENT YAW DAMPER
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YDS - STALL MANAGEMENT YAW DAMPER
YES
MENU
"BITE INSTRUCTIONS"
question (?)
In response to
To display menu
Start or stop Bite
ON/OFF:
YES/NO:
MENU:
menu or results
:To scroll through
OR
STATIC
SENSITIVE
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
65-52822-XX
MOD
X
S/N
ON
OFF
NO
STALL MANAGEMENT
YAW DAMPER
P/N
X
BITE KEYPAD
BITE DISPLAY
BITE INSTRUCTIONS
BITE MODULE
THE SMYD LRU IS AN ELCTRO-STATIC
SENSITIVE DEVICE. USE PROPER
NOTE:
PROCEDURES WHEN HANDLING THE LRU.
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YDS -- SMYD 1 - FUNCTIONAL DESCRIPTION
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General
The stall management yaw damper (SMYD) calculates yaw
damping commands using analog and digital inputs from
airplane sensors. SMYD 1 provides primary yaw damping
through the main rudder PCU.
Power Supplies
Primary power for the yaw damping function is 28v dc.
28v ac is also provided as the reference voltage for
the main rudder PCU LVDT.
The SMYD supplies 28v dc to the yaw damper solenoid
valve on the rudder PCU. When the solenoid energizes,
it sends pressurized hydraulic fluid to the
electrohydraulic servo valve (EHSV).
It also supplies 28v dc as the hold up voltage for the
yaw damper engage switch on the flight control panel.
Yaw Damping
The SMYD CPU contains the control law software for yaw
damping. Primary yaw damping uses this data from these
systems and sensors:
- Left AOA sensor
- Trailing edge flap limit switch S245
- Flight control switches A and B
- Program pins
- Main rudder PCU LVDT
- Inertial reference data (L & R ADIRU)
- Air data (L ADIRU)
- FMCS
- MCP
- SMYD 2.
The AOA sensor input is used by the SMYD to modify the
yaw damper control law as the airplane approaches the
stall condition.
The input from the trailing edge flaps up switch S245
is used by the SMYD to limit the rudder authority. For
primary yaw damping, these are the limits for rudder
travel:
- 2 degrees with flaps Up
- 3 degrees with flaps Down.
The flight control switches send positionn discetes to
the SMYDs. These inputs are used to enable primary yaw
damping (SMYD 1) or secondary yaw damping (SMYD 2).
The program pins determine airplane model and SMYD
position.
Lateral acceleration, yaw rate, roll attitude and roll
rate from both ADIRUS, computed airspeed from the
onside ADIRU, gross weight from the FMCS and yaw damper
command data from SMYD 2 are all used in the yaw damper
control law.
The MCP sends autopilot engage status to the SMYD. The
SMYD uses this data to disengage the yaw damper in the
event of an ADIRU fault with the autopilot engaged.
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When SMYD 1 senses airplane unwanted yaw motion and the
yaw damper is engaged, it supplies a signal to the
EHSV. The current and polarity determine the amount and
direction the EHSV moves. The EHSV applies hydraulic
pressure to the yaw damper actuator in proportion to
SMYD 1 yaw damper commands. The yaw damper actuator
then provides the mechanical input to the main rudder
PCU.
The LVDT on the main rudder PCU sends yaw damper
actuator position data back to SMYD 1 and the yaw
damper indicator on the P2 panel. The SMYD uses the
data to compare its commanded value with actual rudder
movement.
For primary yaw damping, the yaw damper commands from
both SMYDs are compared. If the calculations of the two
SMYDs do not agree, the primary yaw damper disengages.
BITE
The SMYD has BITE test and continuous BITE functions.
It stores failures in fault history for yaw damping and
stall management functions. The keypad on the front of
the SMYD is used to interface with the BITE function.
Sensed faults will automatically disengage the yaw
damper. This will cause the amber yaw damper disengage
annunciator on the flight control panel to illuminate
and followed by the yaw damper engage switch relaxing
back to the OFF position within two seconds.
Loss of either 28v dc or 28v ac voltages will cause the
yaw damper to disenage.
The rudder servo loop is also monitored for correct
operation. The yaw damper will disengage if there is a
difference of 0.5 degrees between the actual servo loop
response and a software modelled servo loop in the
SMYD.
A hardware limiter monitors the output of the limit
function to make sure the correct limit is selected
according to flap position. If it is not within limits,
the yaw damper disengages.
The flaps up switch S245 is monitored by comparing it
to the input from the flap position transmitter input.
If there is a disagreement, the yaw damper will
disengage.
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YDS - SMYD 1 - FUNCTIONAL DESCRIPTION
ARINC
429
INPUT
BITE
SOFTWARE
CALCULATIONS
LEFT AOA SENSOR
T/E FLAP LIMIT
L ADIRU IR
L ADIRU ADR
R ADIRU IR
DISPLAY
SMYD 1
CPU
KEYPAD
FAULT
HISTORY
MAIN RUDDER PCU
EHSV
FMC
SMYD 2
POWER
28V AC
28V DC
ANALOG
INPUTS
ANALOG
OUTPUTS
SOLENOID
VALVE
NOTE: ONLY THE INTERFACES FOR PRIMARY YAW DAMPING ARE SHOWN ON THIS GRAPHIC.
FLT CTRL PANEL
MCP
YAW DAMPER
ENGAGE SWITCH
CROSS CHANNEL
BUS
FLT CTRL PANEL
ARINC
429
OUTPUTS
LVDT
SWITCH S245
PROGRAM PINS
YAW DAMPER
INDICATOR
SMYD 2
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General
You use the yaw damper ON/OFF switch on the flight
control panel to engage the yaw damper.
For the primary yaw damper system, there are these two
indicators in the flight compartment:
- Yaw damper warning light
- Yaw damper indicator.
The yaw damper warning light is on the flight control
panel above the yaw damper ON/OFF switch. The yaw
damper indicator is on the instrument panel.
Engage Switch and Warning Light
To engage the primary yaw damper system (YDS), put the
yaw damper engage switch on the flight control panel to
the ON position. These are the conditions necessary to
engage the primary yaw damper system:
- Hydraulic system B is ON
- Flight control B is ON.
If SMYD 1 does not detect any yaw damper faults, two
seconds later the yaw damper warning light will go off
to show that there is normal yaw damper operation. This
switch is held in the ON position electronically with a
solenoid powered from the SMYD. Only SMYD 1 does
primary yaw damping.
Put the switch to the OFF position to disengage the
YDS. SMYD 1 removes power from the solenoid valve on
the main rudder PCU and, after a two-second delay, the
yaw damper warning light comes on. The warning light
comes on any time the system disengages.
The yaw damper indicator shows the rudder movement due
to primary yaw damper commands from SMYD 1. For primary
yaw damping, rudder movement is limited to 2 degrees
with flaps up and 3 degrees with flaps down. If you
move the rudder with the rudder pedals, the indicator
does not show rudder movement.
To do a test of the indicator and the primary yaw
damper system, do the SMYD 1 servo test in the SMYD
BITE - GROUND TEST described at the end of this
section.
YDS -- OPERATION
YDS -- OPERATION
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YDS - OPERATION
ON
ON
OFF
OFF
a
a
a
a
PRESS
FAIL
SPEED TRIM
FAIL
MACH TRIM
FAIL
AUTO SLAT
FEEL DIFF
a
DAMPER
YAW
YAW DAMPER
ON
OFF
YAW DAMPER
YAW DAMPER INDICATOR
WARNING LIGHT
ENGAGE SWITCH
DISENGAGE
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YDS -- OPERATIONS - ENGAGE INTERLOCKS
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General
There are two SMYDs on the airplane. SMYD 1 controls
primary yaw damping and turn coordination during normal
operation. SMYD 2 operates WTRIS and standby yaw
damping during non normal operation.
The primary yaw damper system (YDS) is engaged using
the yaw damper engage switch on the flight control
panel. This provides the engage request to the SMYD.
The FLT CONT B switch must also be in the ON position to
enable primary yaw damping.
The SMYD then does a self check to ensure that the yaw
damping function is valid. The following parameters are
required for the yaw damper valid self check:
- Power monitor
- Software monitor
- Hardware monitor
- Servo loop monitor
- Hardware limiter monitor
- Onside IR data
- Offside IR data
- DFCS engage status.
The yaw damper function is declared valid when all
monitors pass the self check and both IR functions in
their respective ADIRUs are valid or one IR source is
valid and the autopilot is not engaged.
When the self check has completed satisfactorily, the
actuator solenoid in the main rudder PCU receives 28v
dc and a holding ground is provided for the yaw damper
engage switch. The yaw damper warning light goes out
after two seconds to show that you have yaw damper
operation.
When the yaw damper is selected off or a fault is
present in the SMYD, the yaw damper will disengage. The
yaw damper annunciator and associated master caution
illuminate immediately. After two seconds, the actuator
solenoid in the main rudder PCU is deenergized and the
holding ground is removed from the yaw damper switch.
SMYDs
The two SMYDs are the same. They both do stall
management and yaw damper functions. For stall
management functions, both SMYDs operate together. If
one function fails, the other SMYD will continue to do
stall management functions.
Only one SMYD does yaw damping at a time. SMYD 1 does
only primary yaw damping during normal operations. SMYD
2 does WTRIS and standby yaw damping during standby
operations. This is controlled by the FLT CONTROL A and
B switches on the flight control panel.
SMYD 1 uses the main rudder PCU to move the rudder for
the primary yaw damper function. For primary yaw
damping, SMYD 1 compares its yaw damping calculations
with SMYD 2 before it sends a command to the main
rudder PCU. If the SMYD 2 calculations disagree or if
- 61 -

22-23-00
22-23-00-012.fm
SMYD 2 fails, the yaw damper function in SMYD 1
disengages even though SMYD 2 is not used for primary
yaw damping.
Training Information Point
The electrical ground for the disengage light is
connected in series through both SMYDs. For normal
operation, it is necessary to have both SMYDs installed
on the airplane.
The light test can be done with the master dim and test
system.
- 62 -

22-23-00
22-23-00-012.fm
YDS - OPERATIONS - ENGAGE INTERLOCKS
YD CHANNEL
FLT CONT A
OFF/STANDBY
FLT CONT B
OFF/STANDBY
FLIGHT CONTROL
SMYD 2
MAIN RUDDER PCU
DISENGAGE LIGHT
YAW DAMPER
ACTUATOR
SOLENOID
STANDBY RUDDER PCU
YAW DAMPER
ACTUATOR
SOLENOID
2 SEC
2 SEC
2 SEC
2 SEC
2 SEC
2 SEC
PANEL
SMYD 1
DC POWER
POWER SUPPLY
POWER SUPPLY
28V DC
BUS 1
YAW DAMPER 1
YAW DAMPER 2
YAW
DAMPER
SWITCH
MASTER
WARNING
A A
FLIGHT CONTROL
MODULE
SYSTEM
ON
ON
P18 CIRCUIT BREAKER PANEL
VALID
ENGAGE
ENABLE
YD CHANNEL
VALID
ENGAGE
ENABLE
- 63 -

22-23-00
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General
The SMYD has these BITE functions:
- Continuous monitor
- BITE tests.
Continuous Monitor
The continuous monitor function of BITE monitors the
SMYD LRU for proper operation. When the SMYD has an
internal failure a fault is recorded in fault history.
Some faults will cause the SMYD to have no outputs for
the stall management and yaw damper functions.
BITE Tests
The BITE tests are used to do tests of components and
sensors that interface with the SMYD. They have these
functions:
- Quick system test
- SMYD LRU self test
- Tests of sensors that interface with the SMYD
- Tests to show that functions are within
specification
- Supports fault isolation.
The BITE module on the front of the SMYD LRU has a
keypad with six push-buttons, and a two-line display
with eight characters per line.
BITE Operation
To start the BITE, push the ON/OFF key on the BITE
module. EXISTING FAULTS? shows as the first menu item.
Push the YES key to answer questions and to move down
further in the selected menu item on the display. Push
the NO or down arrow key to see the next menu item. In
some lists, TOP OF LIST or END OF LIST shows for one
second when you move to the top or bottom of the list.
Push the MENU key to exit a menu and move back up one
level to the previous menu. One of these conditions are
necessary to start BITE:
- Flaps Up and VCAS < 60 knots
- On-side engine N1<15% and off-side engine N2<50%.
These conditions make sure that if BITE is ON, it will
turn off prior to takeoff. Also, a time delay will turn
off the BITE control panel if no push-buttons are
pushed for five minutes or longer.
Main Menu
These are the BITE main menu selections:
- EXISTING FAULTS
- FAULTS HISTORY
- GROUND TESTS
- OTHER FUNCTIONS.
At the start of the BITE, EXISTING FAULTS? shows. Push
the YES key to select this menu or use the NO or down
arrow key to go to the next main menu selection.
YDS -- TRAINING INFORMATION POINT - SMYD BITE
YDS -- TRAINING INFORMATION POINT - SMYD BITE
- 64 -

22-23-00
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YES
MENU
"BITE INSTRUCTIONS"
question (?)
In response to
To display menu
Start or stop Bite
ON/OFF:
YES/NO:
MENU :
menu or results
To scroll through
:
OR
STATIC
SENSITIVE
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
65-52822-XX
MOD
X
S/N
ON
OFF
NO
STALL MANAGEMENT
YAW DAMPER
P/N
X
ON
OFF
NO
YES
INTO
EXISTING
FAULTS
YDS - TRAINING INFORMATION POINT - SMYD BITE
EXISTING
FAULTS?
SHOWS TOP OF LIST FOR 1 SECOND
FAULTS
HISTORY?
NO
YES
GROUND
TESTS?
NO
YES
OTHER
FUNCTNS?
NO
YES
2
1
INTO
FAULTS
HISTORY
INTO
GROUND
TESTS
INTO
OTHER
FUNCTIONS
BITE
ON-SIDE ENGINE N1 < 15%
OFF-SIDE ENGINE N2 < 50%
FLAPS UP
AIRSPEED < 60 KNOTS
SHOWS END OF LIST FOR 1 SECOND
2
1
ENABLE
(2 lines, 8 alpha-
numeric characters)
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22-23-00
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Existing Faults
The EXISTING FAULTS test checks the interfaces between
the SMYD and airplane sensors to checks for current
faults. To do the existing faults test, do these steps:
- Turn ON the SMYD BITE
- EXISTING FAULTS? shows as the first menu item
- Push the YES key to enter EXISTING FAULTS.
When you push the YES key for EXISTING FAULTS, the SMYD
BITE will do a check for current faults. If there are
no faults, the display shows NO FAULTS.
If there are faults either for yaw damping or stall
management functions, the the fault description starts
with fault 1. If you then push the down arrow key, the
display will ask if you want to see MORE DETAILS? about
the fault. You can push YES to see more details for the
fault. Or you can push NO or the down arrow key to go to
the next fault.
More Details
If you push the YES key when MORE DETAILS? shows, it
will show the maintenance message number for fault 1.
You can then push the down arrow key to show
thesedetails for the fault:
- Flight deck effect(s) for the fault
- Flight phase in which the fault was detected
- The most likely LRU causing the fault
- Hard or intermittent fault and if it is latched.
To see more faults, push the up arrow key (previous) to
go back to MORE DETAILS?, then push NO or the down
arrow key (next) to see if there are more faults.
The BITE for SMYD 1 interfaces with various airplane
sensors to record faults for the stall management and
primary yaw damper functions for these systems:
- Primary yaw damping system
- Stall Warning System
- Autoslat system
- Performance data.
Reset Latches
After the display of the last fault, the display asks
RESET LATCHES?. Only some faults will latch. To reset,
push the YES switch. The display shows RESET IN
PROGRESS while it resets the latched faults.
YDS -- TRAINING INFORMATION POINT - SMYD BITE - EXISTING FAULTS
YDS -- TRAINING INFORMATION POINT - SMYD BITE - EXISTING FAULTS
- 66 -

22-23-00
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S
R E S E
E
T I N
P R O G R S
YES
(FAULT N)
YDS - TRAINING INFORMATION POINT - SMYD BITE - EXISTING FAULTS
(FAULT 1)
YES
(FAULT
L I S
F
T P
T
O
O
E X I S T I N G
F A U L T S ?
M S G N O :
X X - Y Y Z Z Z
F T
O T H E R
U N C N ?
S
T
F A U L
?
H I S T O R Y
G R O U N D
T E S T S ?
S
F
T
O
D
I
N
E
L
S
F
T
O
D
I
N
E
L
L I S
F
T P
T
O
O
L I S
F
T P
T
O
O
?
S
F
T
O
D
I
N
E
L
YES
YES
S ?
R E S E T
L A T C H E
R E
T A I L S
O
E
M
D
?
T A I L S
E
D
R E
O
M
FAULT
DESCRIPTION
MAINTENANCE
MESSAGE NUMBER
FAULT DETAILS:
FLT DECK EFFECT
MOST LIKELY LRU
LATCHED OR NOT
DETAILS) FLIGHT PHASE
- 67 -

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Fault History
The fault history selection in the SMYD BITE shows
fault information by flight leg stored in non-volatile
memory (NVM). Monitors in the SMYD store fault data in
NVM during these conditions:
- System tests using the SMYD BITE
- Continuous monitoring during normal operation
- Power up tests.
Faults are stored for this number of flight legs:
- Last 64 flight legs
- Maximum of 256 faults.
Only flight legs that have faults show in fault
history. The flight leg changes when the airplane goes
from the ground to air except during touch and go
operations when the airspeed remains above 60 KCAS.
For fault information by flight leg, do these steps:
- Turn on the SMYD BITE
- Use the down arrow key to scroll to FAULT HISTORY?
- When FAULT HISTORY? shows, push the YES key
- Use the up or down arrow keys to scroll to the
desired flight leg and then push the YES key.
More Details
After you select a flight leg with the YES key, the
display shows fault 1 for that flight leg. If you then
push the down arrow key, the display first shows MORE
DETAILS? to ask if you want to see details for fault 1.
If you push the YES key, the display shows details for
fault 1. Under MORE DETAILS? if you push NO or the down
arrow key, the display goes to the next fault in that
flight leg.
Under MORE DETAILS? for fault 1 if you say YES, the
display first shows the maintenance message number for
fault 1. If you then push the down arrow key, the
display shows these details for fault 1:
- Flight deck effect(s) (FDE)
- Flight phase when the fault was detected
- The most likely LRU that caused the fault
- Hard or intermittent fault and if it is latched.
To see more faults, push the up arrow key (previous) to
go back to MORE DETAILS? then push the NO or down arrow
keys to see if there are more faults under the selected
flight leg. To see additional flight legs, push the
MENU key to go back to the flight legs sub-menu.
YDS -- TRAINING INFORMATION POINT - SMYD BITE - FAULT HISTORY
YDS -- TRAINING INFORMATION POINT - SMYD BITE - FAULT HISTORY
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22-23-00
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YES YES
YES
YDS - TRAINING INFORMATION POINT - SMYD BITE - FAULT HISTORY
(FAULT 1)
(FAULT N) (TYPE)
YES
YES
?
T A I L S
M S G N O :
X X - Y Y Z Z Z
E
D S
F
T
O
D
I G T
H
G ( N ) ?
I
N
E
L
E
L
F
L
L I S
F
T P
T
O
O
L I S
F
T P
T
O
O
L I S
F
T P
T
O
O
E X I S T I N G
F A U L T S ?
T
F A U L
?
H I S T O R Y
G R O U N D
T E S T S ?
F T
O T H E R
U N C N ?
S
S
F
T
O
D
I
N
E
L
S
F
T
O
D
I
N
E
L
R E
?
T A I L S
O
E
M
D
S
F
T
O
D
I
N
E
L
L I S
F
T P
T
O
O
I G T
H
G 0 ?
E
L
F
L
R E
O
M
NO
OR
MENU
USE THE MENU KEY
TO RETURN TO THE
PREVIOUS MENU
MENU
- 69 -

22-23-00
22-23-00-018.fm
Ground Tests
GROUND TESTS is one of four main menu items in the SMYD
BITE. On this menu, you can do these functions:
- See the status of discrete inputs and analog
inputs to the SMYD
- See the activity status of ARINC 429 inputs
- Servo test of the yaw damper components on the
rudder PCU
- Test of the BITE display.
These are the menu selections:
- SELF TESTS
- DISCRETE INPUTS
- ARINC 429 INPUTS
- ANALOG INPUTS
- SERVO TEST
- DISPLAY TEST.
To start one of these tests, do these steps:
- On the main menu, use the down (or up) arrow key to
scroll to GROUND TESTS? and push the YES key
ground test that you want and push the YES key.
If the ground test that you selected passes, the
display shows TEST PASSED. If the test fails, the
display shows a fault message under MORE DETAILS. The
information under MORE DETAILS is the same as for the
existing faults test that was discussed previously.
Self Tests
The SELF TEST does a check of the SMYD LRU for internal
faults. When you push YES for self tests, the display
shows TEST IN PROGRESS until the test is complete. If
the SMYD passes the test, the display shows SMYD LRU
OK. If the SMYD does not pass the test, the display
shows SMYD LRU FAIL for 2 seconds, then shows the first
fault.
Discrete Inputs
You do a check of the status of these discrete inputs
from the DISCRETE INPUTS menu for SMYD 1:
- Air/ground relays
- Flaps Up limit switches
- FLT CONTROL B switch
- TO/GA switches (OPEN or GROUND)
- Program pin selections
- Autoslat power availability (PRESENT or MISSING)
- Stick shaker power availability
- Yaw damper power availability.
Use the up (previous) and down (next) arrow keys to
move through the list of discrete inputs.
YDS -- TRAINING INFORMATION POINT - SMYD BITE - GROUND TESTS
- 70 -

22-23-00
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ARINC 429 Test
On the ARINC 429 INPUT menu, you can do a check of the
activity status of these ARINC 429 buses:
- On-side IR bus
- Off-side IR bus
- On-side ADR bus
- CDS DEU bus
- FMC bus
- DFCS MCP bus
- SMYD Cross-channel bus.
Push the YES switch to see if the bus is ACTIVE or
INACTIVE. Use the up and down arrow keys to move
through the list.
Analog Inputs
On the ANALOG INPUTS menu, you do a check of the status
of data from analog sensors that send data to the
SMYDs. For SMYD 1, you can do a check of these analog
sensors for primary yaw damping:
- Left AOA sensor
- Right flap position transmitter
- LVDT on main rudder PCU.
Push the YES switch to select a sensor. Use the up
(previous) or down (next) arrow keys to move through
the list.
Servo Test
With the SERVO TEST you do a test of the yaw damper
components on the rudder PCUs and the interfaces
between the SMYDs and the rudder PCUs. The SMYD 1 BITE
does a test of these primary yaw damper components on
the main rudder PCU:
- Yaw damper EHSV
- Yaw damper LVDT.
Display Test
The DISPLAY TEST lets you do a test of the display on
the BITE module on the front of the SMYD. To do a test
of the display, push the YES key when the DISPLAY TEST
prompt shows.
This test takes 10 seconds. All the LEDs on the left
half of the top line come on first, then all the LEDs on
the right half come on. Next, all the LEDs on the left
half of the bottom line come on, then all the LEDs on
the right half come on. There are eight alphanumeric
characters on each of the two lines. When the test is
complete, DISPLAY TEST? shows on the display. Push the
MENU key to return to the previous menu.
Ground Tests Passed
- 71 -

22-23-00
22-23-00-018.fm
existing faults test that were discussed in a previous
section.
- 72 -

22-23-00
22-23-00-018.fm
YDS - TRAINING INFORMATION POINT - SMYD BITE - GROUND TESTS
YES
YES
YES
YES
START THE TEST
START THE TEST
START THE TEST
YES START THE TEST
YES START THE TEST
F T
E X I S T I N G
F A U L T S ?
L I S
F
T P
T
O
O
O T H E R
U N C N ?
S
T
F A U L
?
H I S T O R Y
G R O U N D
T E S T S ?
S
F
T
O
D
I
N
E
L
S E L F
T E S T ?
D I S C
S
R T E
I N P U T
?
A R I N
S
C 2 9
I N P U T
A N A L O
E
4
G
S E R V O
T E S T ?
?
S
I N P U T
D I S P L Y
T E S T ?
A
YES START THE TEST
L I S
F
T P
T
O
O
USE THE UP OR DOWN ARROW KEYS
TO SCROLL THROUGH THE MENU
1
2
2
1
PUSH THE YES KEY TO START THE TEST
- 73 -

22-23-00
22-23-00-020.fm
Ground Tests - Servo Test
Under the GROUND TESTS menu, the SMYD 1 SERVO TEST does
a test of the yaw damper components on the main rudder
PCU for the primary yaw damping system. The SERVO TEST
consists of these two tests:
- ZERO COMMAND
- SWEEP TEST.
For these tests, hydraulic system B pressure is
necessary and the flight control system B switch on the
flight control panel must be ON.
The BITE provides the instructions to do these tests.
BITE provides warnings about rudder movement and asks
you to make sure the rudder area is clear of equipment
and personnel before you start the test.
Zero Command
For the ZERO COMMAND test, the SMYD commands the rudder
to move to the zero position. SMYD 1 then compares its
commanded value to the value from the LVDT on the main
rudder PCU for rudder position. BITE shows the LVDT
values in degrees.
Sweep Test
For the SWEEP TEST, SMYD 1 commands the main rudder PCU
to move the rudder left, right, and then to the zero
position. During this test, rudder travel is limited to
2 degrees with flaps up, and 3 degrees with flaps down.
During the sweep test, the SMYD 1 servo command is
compared to the LVDT value from the main rudder PCU to
see if the rudder moves the commanded value. Rudder
movement shows on the SMYD BITE display in degrees of
rudder travel, and on the yaw damper indicator in the
flight deck.
If the test passes, the display shows TEST PASSED. Push
the MENU key to go to the previous sub-menu, SERVO
TEST. If the test fails, the display shows TEST FAILED
and then shows the first fault. Push the down arrow key
and the display asks if you want to see MORE DETAILS.
Push YES to see more details about the fault.
YDS -- TRAINING INFORMATION POINT - SMYD BITE - SERVO TEST
YDS -- TRAINING INFORMATION POINT - SMYD BITE - SERVO TEST
- 74 -

22-23-00
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NO
YDS - TRAINING INFORMATION POINT - SMYD BITE - SERVO TEST
YES
YES
YES
YES
YES
R U D D E
C E A R E D ?
R
L
S Y S B
H D O N ?
O
S E R V
T E S T ?
W A R N I N G !
W A R N I N G ! A
F L T C T R L
O N ?
B
Y W D M P R
E N G A G E D ?
Z E R O
S W E E P
T E S T ?
T E S T
I
F A L E D
( V A L U E )
E T
R U C D
D M
L F
L V D T
( V A L U E )
R U C D
D M
R I G H T
R U C D
D M
Z E R O
L V D T
( V A L U E )
L V D T
( V A L U E )
R U D D E R
M O V E M E N T
Y C M D
D
L V D T
( V A L U E )
D
E N Z E R O
C O M M A N D
C O M M A N D
?
?
R U D D E R
M O V I N G
R U D D E R
M O V I N G
S
P A S E D
T E S T
YES
YES
YES
Y
1 BITE SHOWS INIT NOT COMPLETE
IF INITIALIZATION IS NOT COMPLETE
1
MENU
(FAULT 1)
YES
D E L
T A I S ?
M O R E
OR
USE THE MENU KEY TO RETURN
MENU
TO THE PREVIOUS MENU
O
S E R V
T E S T ?
PUSH YES FOR
MORE DETAILS
NO
NO
- 75 -

22-23-00
22-23-00-019.fm
Other Functions
OTHER FUNCTIONS is the last of four main menu items in
the SMYD BITE. It has these sub-menus:
- SYSTEM CONFIG
- I/O MONITOR
- SET OUTPUTS.
To enter OTHER FUNCTIONS, push the YES key for this
selection. You can then scroll through the sub-menu
items with the arrow keys, and push the YES key to see
data for the desired selection.
System Configuration
In the SYSTEM CONFIG sub-menu, you can verify these
system configurations for the SMYD LRU:
- Part number
- Software Level
- Position (1 or 2) in E/E bay
- Airplane model
- FAA or CAA/FAA.
This menu provides hardware part number and software
level, SMYD position, airplane type, and FAA or FAA/CAA
configuration for speed tape displays of Vmo/Mmo.
I/O Monitor
In the I/O MONITOR sub-menu you can verify these ARINC
429 input/output data to the SMYD:
- ARINC 429 inputs
- ARINC 429 low speed outputs
- ARINC 429 high speed outputs.
You can see the actual data being transmitted on data
words that you select for these systems:
- On-side IR bus
- Off-side IR bus
- On-side ADR bus
- CDS DEU bus
- FMC bus
- DFCS MCP bus
- SMYD cross-channel bus.
The value of the data transmitted on each data word
shows and includes the units such as degrees or degrees
per second, knots airspeed, gross weight, and Bit
status whether 1 or 0.
Refer to the section on SMYD digital interfaces for
information about digital input/output data.
Set Outputs
In the SET OUTPUTS sub-menu, you do a test of the two
output signals for EFSM operation. SS CMD does a test
of the 28v dc power supply to the stick shaker (SS) and
the elevator feel shift module (EFSM). The combined SS
CMD & EFSM CMD does a test of the electrical ground
signal provided to the EFSM and completes the circuit
for EFSM operation.
YDS -- TRAINING INFORMATION POINT - SMYD BITE - OTHER FUNCTIONS
YDS -- TRAINING INFORMATION POINT - SMYD BITE - OTHER FUNCTIONS
- 76 -

22-23-00
22-23-00-019.fm
YES
YDS - TRAINING INFORMATION POINT - SMYD BITE - OTHER FUNCTIONS
YES
YES
YES
TO LIST OF
SYSTEM
CONFIGURATION
ITEMS
YES
DISPLAYS ARINC
429 INPUTS ON
DISPLAYS ARINC
429 LOW SPEED
F T
E X I S T I N G
F A U L T S ?
L I S
F
T P
T
O
O
O T H E R
U N C N ?
S
T
F A U L
?
H I S T O R Y
G R O U N D
T E S T S ?
S
F
T
O
D
I
N
E
L
I / O
M O N I T O R ?
S
F
T
O
D
I
N
E
L
L I S
F
T P
T
O
O
S
F
T
O
D
I
N
E
L
L I S
F
T P
T
O
O
?
A R I N C 4 2
I N P U T S
S Y S T E M
C O N F I G ?
9
A R I N C 4 2 9
D A T A ?
O T H E R
S
O U T P U T ?
YES
S E T
O U T P U T S ?
YES TO SS CMD AND
NO NO
OUTPUTS ON
DATA WORDS
DISPLAYS ARINC
429 HIGH SPEED
OUTPUTS ON
DATA WORDS
EFSM CMD TESTS
NO
DATA WORDS
MENU
- 77 -

22-23-00
22-23-00-021.fm
General
This page is for reference.
YDS -- SMYD 1 - SYSTEM SUMMARY
YDS -- SMYD 1 - SYSTEM SUMMARY
- 78 -

22-23-00
22-23-00-021.fm
YDS - SMYD 1 - SYSTEM SUMMARY
R ADIRU
SMYD 1
LVDT
MAIN RUDDER PCU
MCP
L ADIRU
28V DC
28V DC
28V AC
EHSV
SOLENOID VALVE
LEFT AOA SENSOR
FLT CTRL B SWITCH
YD ENGAGE SWITCH
IR DATA
SMYD 2
X-CHANNEL BUS
YAW DAMPER
ENGAGE SWITCH
YAW DAMPER
ENGAGE LIGHT
ON/OFF
ON/OFF
YD ENGAGE
COMMAND
THIS PAGE SHOWS SMYD 1
COMMANDS
YAW DAMPER
RUDDER MOVEMENT
YD ENGAGE
INTERLOCK
YD ACTUATOR
POSITION
PRIMARY YD
ADR DATA
IR DATA
FOR PRIMARY
YAW DAMPING
INDICATOR
FLAP POSITION
TE FLAP POSITION XMTRS
FLAPS UP/NOT UP
ANGLE OF ATTACK
RA
INTERFACES FOR THE PRIMARY
YAW DAMPING SYSTEM ONLY.
NOTE:
FMC
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Purpose
The wheel to rudder interconnect system (WTRIS) assists
turns during flight control manual reversion operations
when both flight control A and B hydraulics are OFF,
and the standby system is ON. The WTRIS commands a
small amount of rudder movement as a function of the
captain control wheel aileron input to help turns.
AOA - angle of airflow
ARINC - Aeronautical Radio Incorporated
ATR - Austin Trumbull Radio
BITE - built-in test equipment
CPU - central processing unit
DC - direct current
EHSV - electrohydraulic servo valve
IR - inertial reference
I/O - input/output
LVDT - linear variable differential transformer
MCP - mode control panel (DFCS)
N1 - engine low pressure rotor (fan) speed
N2 - engine high pressure rotor speed
NN - a number from 01 to 99
PCU - power control unit
V - volts
WTRIS - wheel to rudder interconnect system
YDS - yaw damper system
WHEEL TO RUDDER INTERCONNECT SYSTEM -- INTRODUCTION
WHEEL TO RUDDER INTERCONNECT SYSTEM -- INTRODUCTION
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WHEEL TO RUDDER INTERCONNECT SYSTEM - INTRODUCTION
YAW DAMPER COMPONENTS
ON STANDBY RUDDER PCU
CONTROL WHEEL
POSITION SENSOR
(CAPT SIDE)
SMYD 2
(E/E BAY)
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WTRIS -- GENERAL DESCRIPTION
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General
The wheel-to-rudder interconnect system (WTRIS) moves
the rudder to help turns during flight control manual
reversion when on standby hydraulics. For the WTRIS
function SMYD 2 has interfaces with these components:
- Control wheel position sensor (captain)
- Yaw damper disengage light
- Flight control panel switches
- Standby yaw damper solenoid valve
- Standby EHSV
- Standby LVDT
- FMC
- Trailing edge flaps up limit switches
- Left flap position transmitter.
SMYD 2 gives rudder movement commands for WTRIS and
standby yaw damping and turn coordination during flight
control manual reversion when on standby hydraulics.
SMYD 2 receives data from airplane sensors, switches
and components. SMYD 2 uses the data to calculate and
send commands to the standby rudder PCU to move the
rudder.
Control Wheel Position Sensor
The captain control wheel (CW) position sensor senses
pilot aileron input and sends an analog signal to the
SMYD 2 to calculate a command for left/right rudder
movement for WTRIS.
Yaw Damper Engage Switch and Disengage Light
You engage WTRIS and standby yaw damping with the yaw
damper switch on the flight control panel. The
disengage warning light is above the switch.
Standby Rudder PCU
The standby rudder PCU is a hydraulic actuator that
moves the rudder in response to pilot rudder inputs
when on standby hydraulic pressure. During standby
operation SMYD 2 sends commands to the yaw damper
components on the standby rudder PCU.
ADIRU
The air data inertial reference units (ADIRUs) send
data to the SMYDs. The data includes airspeed,
attitude, and yaw and roll rates and accelerations.
FMC
The FMC gives airplane gross weight to the SMYDs.
Trailing Edge Flaps Up Limit Switches
The trailing edge flaps up limit switches send data to
the SMYD to put a limit on rudder travel when the flaps
are up.
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Left Flap Position Transmitter
The left flap position transmitter sends data to SMYD
2.
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ON
ON
OFF
OFF
DIFF
FAIL
SPEED TRIM
FAIL
MACH TRIM
FAIL
AUTO SLAT
FEEL
DAMPER
YAW
YAW DAMPER
ON
OFF
SPOILER
B
A
OFF
UP
OFF
ARM
DOWN
ALTERNATE FLAPS
LOW
PRESSURE
LOW
PRESSURE
LOW
PRESSURE
STANDBY HYD
RUD
RUD
STBY STBY
B ON
OFF
A ON
OFF
A B
FLT CONTROL
LOW
QUANTITY
STBY
RUD ON
PRESS
RUDDER
CONTROL WHEEL
RIGHT AOA SENSOR
FMC
OTHER SENSORS
POSITION SENSOR
ADIRU (2)
SMYD 2
(CAPT SIDE)
LEFT FLAP POSITION TRANSMITTER
FWD
STANDBY RUDDER PCU
WTRIS - GENERAL DESCRIPTION
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Flight Compartment
The yaw damper engage switch and the disengage light
are on the flight control panel.
Forward Nose Compartment
The control wheel position sensors are at the bottom of
the captain and first officer control columns below the
floor. Only the captain sensor sends data to SMYD 2.
WTRIS -- COMPONENT LOCATIONS
WTRIS -- COMPONENT LOCATIONS
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ON
ON
OFF
OFF
a
a
a
a
DIFF
FAIL
SPEED TRIM
FAIL
MACH TRIM
FAIL
AUTO SLAT
FEEL
a
DAMPER
YAW
YAW DAMPER
ON
OFF
SPOILER
B
A
OFF
UP
OFF
ARM
DOWN
ALTERNATE FLAPS
a
LOW
PRESSURE
a
LOW
PRESSURE
a
LOW
PRESSURE
STANDBY HYD
a
RUD
RUD
STBY STBY
B ON
OFF
A ON
OFF
A B
FLT CONTROL
LOW
QUANTITY
STBY
RUD ON
a
PRESS
WTRIS - COMPONENT LOCATIONS
CAPT CONTROL WHEEL
FWD
POSITION SENSOR
YAW DAMPER
YAW DAMPER
DISENGAGE LIGHT
ENGAGE SWITCH
FLIGHT CONTROL
SYSTEM A SWITCH
FLIGHT CONTROL
SYSTEM B SWITCH
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The SMYD 2 is on the E3-2 shelf in the electronic
equipment bay.
WTRIS -- ELECTRONIC EQUIPMENT COMPARTMENT COMPONENT LOCATIONS
WTRIS -- ELECTRONIC EQUIPMENT COMPARTMENT COMPONENT LOCATIONS
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WTRIS - ELECTRONIC EQUIPMENT COMPARTMENT COMPONENT LOCATIONS
ELECTRICAL EQUIPMENT COMPARTMENT
(LOOKING AFT)
- SMYD 2
- SMYD 1 (REF)
E3-2 SHELF
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Power
SMYD 2 gets 28v dc from DC bus 1 and 28v ac from
transfer bus 1. 28v dc power goes from SMYD 2 to the yaw
damper engage switch.
The linear variable differential transformer (LVDT) on
the standby rudder PCU gets 28v ac from the same
circuit as SMYD 2.
Digital Data
SMYD 2 receives airplane gross weight from the FMC.
SMYD 2 receives these air data from the right ADIRU:
- Airspeed
- Impact pressure.
SMYD 2 receives these inertial data from the left and
right ADIRUs:
- Lateral acceleration
- Roll angle
- Roll rate
- Yaw rate.
Analog Signals
SMYD 2 sends commands to the standby rudder PCU to
assist turns during flight control manual reversion,
and for standby yaw damping/turn coordination. The LVDT
on the standby rudder PCU sends rudder position data to
SMYD 2 about rudder movement.
The trailing edge flaps up limit switches send flaps
up/not up data to SMYD 2 to limit rudder movement when
the flaps are up.
The left flap position transmitter sends flap position
data to SMYD 2 to use in stall warning, WTRIS and yaw
damping command calculation.
The right AOA sensor sends angle-of-airflow information
to SMYD 2 to use in stall warning, WTRIS and yaw
damping command calculation.
Power goes from the DC power and dim control to the yaw
damper disengage light.
The captain control wheel (CW) position sensor sends
control wheel aileron input information to SMYD 2 for
the WTRIS function.
During standby hydraulic operations, when you turn ON
the yaw damper engage switch, an engage signal goes
through SMYD 2 to the yaw damper solenoid valve on the
standby rudder PCU to engage the yaw damper. SMYD 2
commands rudder movement using the standby EHSV. The
flight control panel switches for system A and B must
be in the OFF or STBY RUD position to enable SMYD 2 for
WTRIS and standby yaw damping.
WTRIS -- INTERFACES
WTRIS -- INTERFACES
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WTRIS - INTERFACES
RIGHT ADIRU
LEFT ADIRU
SMYD 2
AIRSPEED
LATERAL ACC
ROLL ANGLE
ROLL RATE
YAW RATE
LATERAL ACC
ROLL ANGLE
ROLL RATE
YAW RATE
COMMAND
RUDDER
STANDBY RUDDER PCU
TRAILING EDGE FLAPS UP
FLAPS UP
YD ENGAGE REQUEST
28V DC POWER
28V DC
BUS 1
YAW DAMPER
POWER
LIMIT SWITCHES
LVDT YAW DAMPER
RUDDER POSITION
EHSV
SOLENOID VALVE
FMC
GROSS WEIGHT
IMPACT PRESSURE
RIGHT AOA SENSOR
ANGLE-OF-AIRFLOW
28V AC
XFR BUS 1
CAPT CONTROL WHEEL
POSITION SENSOR
CONTROL WHEEL
YAW DAMPER
P6-1 CB PANEL
POSITION
SIGNALS
FEEDBACK
ENGAGE COMMAND
ENGAGE
ENGAGE
ENABLE
SWITCH SOLENOID
SIGNAL
THIS DIAGRAM ONLY SHOWS SMYD INTERFACES
FOR WTRIS AND STANDBY YAW DAMPING
NOTE:
- - - - - - - - - -
YD DISENGAGE LIGHT
DC POWER AND
DIM CONTROL
LEFT FLAP POSITION XMTR
FLAP POSITION
POWER
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Purpose
SMYD 2 calculates and sends commands to the yaw damper
components on the standby rudder PCU to move the rudder
for WTRIS and standby yaw damping/turn coordination.
SMYD 2 uses control wheel (aileron) position data to
command small amounts of rudder movement to help turns
during flight control manual reversion, when on standby
hydraulics. SMYD 2 uses inertial data from the ADIRU to
detect unwanted yaw motion due to dutch roll or
turbulence.
SMYD 2 also does stall management functions.
The SMYD weighs approximately 10 lbs. It uses 10 watts
of power. A standard Boeing BITE module is on the front
of the LRU and interfaces with the SMYD to monitor
operation and record faults. The BITE module has these
features on the front of the unit:
- Bite instructions on the label
- Display
- Keypad.
Bite Instructions
Bite instructions on the BITE module tell how to test
the unit and move through the BITE software.
Display
The SMYD BITE module has a two-line amber display. Each
line has eight alphanumeric characters. The display
shows messages about the type of fault, maintenance
message number, and fault details when you do BITE. The
SMYD 2 BITE interfaces with and provides fault data for
stall management functions and for standby yaw damping
and WTRIS.
Keypad
You use the keys on the BITE module to operate the SMYD
BITE. The keypad has these keys:
- ON/OFF
- MENU
- YES
- NO
- Up arrow (previous)
- Down arrow (next).
See the SMYD section for more information about BITE
operation.(AMM PART I 27-32)
WTRIS -- STALL MANAGEMENT YAW DAMPER
WTRIS -- STALL MANAGEMENT YAW DAMPER
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WTRIS - STALL MANAGEMENT YAW DAMPER
YES
MENU
"BITE INSTRUCTIONS"
question (?)
In response to
To display menu
Start or stop Bite
ON/OFF:
YES/NO:
MENU :
menu or results
To scroll through
:
OR
STATIC
SENSITIVE
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
65-52822-XX
MOD
X
S/N
ON
OFF
NO
STALL MANAGEMENT
YAW DAMPER
P/N
X
DISPLAY
KEYPAD
BITE MODULE
BITE INSTRUCTIONS
OBSERVE PRECAUTIONS FOR
NOTE:
DEVICES WHEN YOU HANDLR
ELECTRO-STATIC SENSITIVE
THE SMYD LRU.
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General
SMYD 2 uses analog and digital data inputs to calculate
rudder commands for WTRIS and standby yaw damping/turn
coordination.
Engage Interlock
SMYD 2 supplies 28v dc to the yaw damper solenoid valve
on the standby rudder PCU. When this solenoid valve is
energized it supplies hydraulic fluid to the EHSV to
operate the yaw damper actuator on the standby rudder
PCU to move the rudder for WTRIS and standby yaw
damping.
WTRIS
The WTRIS function of SMYD 2 uses control wheel aileron
inputs from the captain control wheel position sensor
to command small amounts of rudder movement. This helps
turn the airplane during flight control manual
reversion when operating on standby hydraulics.
The SMYD central processing unit (CPU) operates the
control law software. For SMYD 2, the software
calculations are based on inputs from these components:
- Captain control wheel position sensor
- ADIRUs (inertial and air data)
- Right AOA sensor
- FMC
- Standby rudder PCU LVDT
- Trailing edge flap up limit switches.
SMYD 2 receives inertial data from the ADIRU to
calculate commands for standby yaw damping and turn
coordination. These commands go to the yaw damper EHSV
on the standby rudder PCU to move the rudder.
The EHSV applies hydraulic pressure to the yaw damper
actuator and the actuator makes a mechanical summing
input to the rudder PCU to move the rudder to assist
turns and to reduce unwanted yaw. The standby LVDT
sends yaw damper actuator position data about rudder
movement to SMYD 2.
WTRIS only operates at Mach < 0.4. The gain schedule
changes from 1 (full gain) at Mach < 0.3 to zero gain at
Mach > 0.4.
For WTRIS and standby yaw damping, these are the limits
for rudder commands:
- 2 degrees with flaps up
- 2.5 degrees with flaps not up.
BITE
The SMYD has BITE test and continuous BITE. It stores
failures in fault history. The keypad is for operator
interface. The display shows test results and prompts
for input.
WTRIS -- SMYD 2 - FUNCTIONAL DESCRIPTION
WTRIS -- SMYD 2 - FUNCTIONAL DESCRIPTION
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WTRIS - SMYD 2 - FUNCTIONAL DESCRIPTION
ARINC
429
INPUT
BITE
SOFTWARE
CALCULATIONS
ANALOG
INPUTS
ANALOG
OUTPUT
R AOA SENSOR
TE FLAP UP
LIMIT SWITCH
R ADIRU IR
R ADIRU ADR
L ADIRU IR
STALL MGT
YAW DAMPER 1
DISPLAY
SMYD 2
CPU
CROSS CHANNEL
BUS
POWER
KEYPAD
FAULT
HISTORY
LVDT ON STBY
CW SENSOR
FMC GW
SMYD 1
28V DC
28V DC
WTRIS
YAW DAMPING
28V AC
ARINC
429
OUTPUT
RUDDER PCU
STBY RUDDER
PCU EHSV
YAW DAMPER
ENGAGE SWITCH
STBY RUDDER
PCU SOLENOID
VALVE
NOTE: ONLY INTERFACES FOR WTRIS AND STBY YAW
DAMPING ARE SHOWN ON THIS DIAGRAM.
L FLAP POS
TRANSMITTER
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General
The yaw damper engage switch on the flight control
panel operates the WTRIS and standby yaw damper. The
yaw damper disengage warning light is above the engage
switch.
To put the WTRIS and standby yaw damper on, do these
steps on the flight control panel:
- Put the FLT CONT A and B switches to positions
other than the ON position
- Put at least one of these switches to STBY RUD
- Put the yaw damper switch to ON.
When you put the flight control A and B switches to
positions other than the ON position, a signal enables
SMYD 2 for WTRIS and standby yaw damping. When you put
one of these switches to the STBY RUD position, standby
hydraulic pressure goes to the standby rudder PCU to
move the rudder.
After you put the yaw damper engage switch to ON and
then a two-second delay, the yaw damper engage light
goes off to show that WTRIS and standby yaw damping are
in operation.
If there is a system fault, SMYD 2 removes power from
the engage solenoid valve on the standby rudder PCU to
stop hydraulic fluid to the EHSV. SMYD 2 also removes
power from the yaw damper engage switch on the flight
control panel. After a two-second delay the engage
switch moves to OFF, and the yaw damper disengage light
comes ON to show the system is disengaged.
WTRIS -- OPERATIONS
WTRIS -- OPERATIONS
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WTRIS - OPERATIONS
ON
ON
OFF
OFF
a
a
a
a
DIFF
FAIL
SPEED TRIM
FAIL
MACH TRIM
FAIL
AUTO SLAT
FEEL
a
DAMPER
YAW
YAW DAMPER
ON
OFF
SPOILER
B
A
OFF
UP
OFF
ARM
DOWN
ALTERNATE FLAPS
a
LOW
PRESSURE
a
LOW
PRESSURE
a
LOW
PRESSURE
STANDBY HYD
a
RUD
RUD
STBY STBY
B ON
OFF
A ON
OFF
A B
FLT CONTROL
LOW
QUANTITY
STBY
RUD ON
a
PRESS
YAW DAMPER
DISENGAGE
WARNING LIGHT
FLT CONTROL
A AND B SWITCHES
ENGAGE SWITCH
OFF
UP
OFF
ARM
DOWN
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General
SMYD 2 operates the wheel to rudder interconnect system
(WTRIS) and standby yaw damping during standby
operations. For WTRIS and standby yaw damping, SMYD 2
requires that both flight control A and B hydraulic
switches be OFF, with at least one switch in STBY RUD
to provide standby hydraulic pressure to the standby
rudder PCU.
To engage the WTRIS and standby yaw damping, you put
the yaw damper engage switch on the flight control
panel to the ON position. Two seconds later, the yaw
damper warning light goes out to show these systems are
operating. The switch is held in the ON position with
power from SMYD 2.
Put the switch in the OFF position to disengage the
WTRIS and standby yaw damping. The yaw damper warning
light comes on. The warning light comes on anytime the
system is disengaged. During a system fault and after
disengagement, the SMYD 2 removes power from the engage
switch solenoid so that the switch moves to the OFF
position.
The electrical ground for the disengage light is
connected in series through both SMYDs. For normal
operation, both SMYDs are necessary on the airplane.
You can do a test of the light with the master dim and
test system.
SMYD
When a SMYD computer is in the number 2 position it
operates the WTRIS and standby yaw damping. These
systems only operate when in flight control manual
reversion mode. This is when flight control hydraulic
system A and B are OFF and the standby system is ON.
WTRIS -- OPERATIONS - ENGAGE INTERLOCKS
WTRIS -- OPERATIONS - ENGAGE INTERLOCKS
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WTRIS - OPERATIONS - ENGAGE INTERLOCKS
YD CHANNEL OK
FLT CONT A
OFF/
FLT CONT B
OFF/
FLIGHT CONTROL
SMYD 2
DISENGAGE LIGHT
STANDBY RUDDER PCU
YAW DAMPER
ACTUATOR
SOLENOID
2 SEC
2 SEC
2 SEC
YD CHANNEL OK
2 SEC
2 SEC
2 SEC
PANEL
NC
SMYD 1
NC
DC POWER
POWER SUPPLY
POWER SUPPLY
PROGRAM
PINS
PROGRAM
PINS
28V DC
BUS 1
YAW DAMPER 1
YAW DAMPER 2
YAW
DAMPER
SWITCH
MASTER
WARNING
A A
FLIGHT CONTROL
PANEL
SYSTEM
ON
ON
P18 CIRCUIT BREAKER PANEL
MAIN RUDDER PCU
YAW DAMPER
ACTUATOR
SOLENOID
STANDBY
STANDBY
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General
The SMYD has these BITE functions:
- Continuous monitor
- BITE Tests.
Continuous Monitor
The continuous monitor function of BITE monitors the
SMYD LRU for proper operation. When the SMYD has an
internal failure, a fault is recorded in fault history.
Some faults cause the SMYD to have no outputs for the
stall management and yaw damper functions.
BITE Tests
BITE Tests are used to do tests of components and
sensors that interface with the SMYD. It has these
functions:
- Quick system test
- Tests of sensors that interface with the SMYD
- Tests to show functions are within specification
- Supports fault isolation.
The BITE module on the front of the SMYD LRU has a
keypad with six push-buttons, and a two-line display
with eight characters per line.
BITE Operation
To start the BITE, push the ON/OFF key on the BITE
module. EXISTING FAULTS? shows as the first menu item.
Push the YES key to answer questions and to move down
further in the selected menu item on the display. Push
the NO or down arrow key to see the next menu item. In
some lists, TOP OF LIST or END OF LIST shows for one
second when you move to the top or bottom of the list.
Push the MENU key to exit the menu and move back up one
level to the previous menu. One of these conditions is
necessary to start BITE:
- Flaps up and VCAS < 60 knots
- On-side engine N1<15% and off-side engine N2<50%.
These BITE start conditions make sure that if BITE is
ON, it will turn off before takeoff. Also, a time delay
turns off the BITE control panel if no push-buttons are
pushed for five minutes or longer.
Main Menu
These are the four main menu selections in SMYD BITE:
- EXISTING FAULTS
- FAULTS HISTORY
- GROUND TESTS
- OTHER FUNCTIONS.
At the start of the BITE, EXISTING FAULTS? shows. Push
the YES key to select this menu or use the NO or down
arrow key to go to the next main menu selection.
WTRIS -- TRAINING INFORMATION POINT - SMYD BITE
WTRIS -- TRAINING INFORMATION POINT - SMYD BITE
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INTO
FAULTS
HISTORY
YES
EXISTING
FAULTS?
INTO
EXISTING
FAULTS
1
WTRIS - TRAINING INFORMATION POINT - SMYD BITE
SHOWS TOP OF LIST FOR 1 SECOND
YES
MENU
"BITE INSTRUCTIONS"
question (?)
In response to
To display menu
Start or stop Bite
ON/OFF:
YES/NO:
MENU :
menu or results
:To scroll through
OR
STATIC
SENSITIVE
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
65-52822-XX
MOD
X
S/N
ON
OFF
NO
STALL MANAGEMENT
YAW DAMPER
P/N
X
NO
FAULTS
HISTORY?
GROUND
TESTS?
NO
YES
OTHER
FUNCTNS?
NO
YES
2
1
INTO
GROUND
TESTS
INTO
OTHER
FUNCTIONS
SHOWS END OF LIST FOR 1 SECOND
2
FLAPS UP
AIRSPEED < 60 KNOTS
BITE
ENABLE
ON-SIDE ENG N1 < 15%
OFF-SIDE ENG N2 < 50%
ON
OFF
NO
YES
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WTRIS -- TRAINING INFORMATION POINT - SMYD BITE - GROUND TESTS
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27-24-00
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Ground Test
GROUND TESTS is one of the four main menu items in the
SMYD BITE. In this menu, you can do these tests:
- SELF TESTS
- DISCRETE INPUTS
- ARINC 429 INPUTS
- ANALOG INPUTS
- SERVO TEST
- DISPLAY TEST.
To start one of these tests, do these steps:
- In the main menu use the down (or up) arrow key to
scroll to GROUND TESTS? and press the YES key
ground test that you want and press the YES key.
display shows a fault message under MORE DETAILS, and
provides detailed information about the fault.
Self Tests
The SELF TEST does a check of the SMYD LRU for internal
faults. When you push YES, the display shows
TEST IN PROGRESS until the test is complete. If the
SMYD passes the test, the display shows SMYD LRU OK. If
the SMYD does not pass the test, the display shows
SMYD LRU FAIL for 2 seconds, then shows the first
fault.
Discrete Inputs
You do a check of the status of these discrete inputs
from the DISCRETE INPUTS menu.
- Air/ground relays
- Flaps up limit switches
- Flight control panel switches
- Program pin selections
- TO/GA switch status (OPEN or GROUND)
- Autoslat power availability (PRESENT or MISSING)
- Stick shaker power availability
- Yaw damper power availability.
Push the YES key to see the list of discrete inputs.
Use the up (previous) and down (next) arrow keys to
move through the list.
ARINC 429 Test
In the ARINC 429 INPUT menu, you can do a check of the
activity status of ARINC 429 buses for these systems:
- On-side IR bus
- Off-side IR bus
- On-side ADR bus
- CDS DEU bus
- FMC bus
- DFCS MCP bus
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- SMYD cross-channel bus.
Push the YES key to see if the bus is ACTIVE or
INACTIVE. Use the up and down arrow keys to move
through the list.
The GROUND TESTS menu only shows whether the data bus
for each system is active or inactive. To observe ARINC
429 data for these systems, go to the OTHER FUNCTIONS
selection in the main menu.
Analog Inputs
In the ANALOG INPUTS menu, you do a check of the status
of data from analog sensors that send data to the SMYD.
For SMYD 2 (WTRIS and standby yaw damping systems) a
check can be done for these analog sensors:
- Right AOA sensor
- Left flap position transmitter
- LVDT on standby rudder PCU
- Captain control wheel position sensor.
Push the YES key to select an analog sensor. Use the up
(previous) or down (next) arrow keys to move through
the list.
Servo Test
In SMYD 2 BITE, you can use the SERVO TEST to do a test
of the yaw damper components on the standby rudder PCU
and their interface with SMYD 2. You do a test of these
components:
- Standby yaw damper solenoid valve
- Standby yaw damper EHSV
- Standby yaw damper LVDT.
Display Test
The DISPLAY TEST lets you do a test of the display on
the BITE module on the front of the SMYD. To do a test
of the display, push the YES key when the DISPLAY TEST
prompt shows.
The test takes about 10 seconds. All the LEDs on the
left half of the top line will come on first, then all
the LEDs on the right half will come on. Next all the
LEDs on the left half of the bottom line will come on,
then all the LEDs on the right half will come on. There
are eight characters on each of the two lines. When the
test is complete, DISPLAY TEST? shows on the display.
Push the MENU key to return to the previous menu.
Ground Tests Passed
If the ground test that you selected passes the test,
the display shows TEST PASSED. If the test fails, the
existing faults test that were discussed in a previous
section.
- 104 -

27-24-00
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WTRIS - TRAINING INFORMATION POINT - SMYD BITE - GROUND TESTS
YES
YES START THE TEST
G R O U N D
T E S T S ?
S E L F
T E S T ?
D I S C
S ?
R T E
I N P U T
?
A R I N
S
C 2 9
I N P U T
A N A L O
E
4
G
S E R V O
T E S T ?
?
S
I N P U T
D I S P L Y
T E S T ?
A
L I S
F
T P
T
O
O
USE ARROW KEY OR NO KEY
TO SCROLL THROUGH THE
GROUND TESTS SUB-MENU
NO
- 105 -

27-24-00
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Ground Tests - Servo Test
Under the GROUND TESTS menu, the SERVO TEST for SMYD 2
does a test of the yaw damper components on the standby
rudder PCU for the WTRIS and standby yaw damping
system. The SERVO TEST consists of these two tests:
- ZERO COMMAND
- SWEEP TEST.
For these tests, standby hydraulic system pressure is
necessary. On the flight control panel, at least one
flight control switch, A or B, must be in STBY RUD and
the other flight control switch may be OFF or STBY RUD.
Before the start of the test, the SMYD 2 BITE provides
warnings about rudder movement and asks you if the
rudder area is clear. The BITE then provides
instructions to do the tests.
Zero Command
For the ZERO COMMAND test, SMYD 2 commands the rudder
to move to the zero position. The SMYD then compares
its commanded value with the value from the LVDT on the
standby rudder PCU.
Sweep Test
For the SWEEP TEST, SMYD 2 commands the standby rudder
PCU to move the rudder left, right, and then to the
zero position. During the test, left/right rudder
movement is limited to 2 degrees with flaps up, or 2.5
degrees with flaps down. The SMYD 2 servo command is
compared to the LVDT value from the standby rudder PCU
to see if the rudder moved the commanded value. During
the test, rudder movement shows on the SMYD BITE
display in degrees of rudder movement.
If the test passes, the display shows TEST PASSED. Push
the MENU key to go to the previous sub-menu SERVO TEST.
If the test fails, the display shows TEST FAILED and
then shows the first fault. Push the down arrow key and
the display will ask if you want to see MORE DETAILS.
Push YES to see more details about the fault.
WTRIS -- TRAINING INFORMATION POINT - SMYD BITE - SERVO TEST
WTRIS -- TRAINING INFORMATION POINT - SMYD BITE - SERVO TEST
- 106 -

27-24-00
27-24-00-017.fm
A
Y W D M P R
E N G A G E D ?
R U D D E
C E A R E D ?
R
L
O
S E R V
T E S T ?
W A R N I N G !
W A R N I N G !
F L T C T R L
S T B Y ?
B
Z E R O
S W E E P
T E S T ?
( V A L U E )
E T
R U C D
D M
L F
L V D T
( V A L U E )
R U C D
D M
R I G H T
R U C D
D M
Z E R O
L V D T
( V A L U E )
L V D T
( V A L U E )
R U D D E R
M O V E M E N T
Y C M D
D
L V D T
( V A L U E )
D
E N Z E R O
C O M M A N D
C O M M A N D
?
?
R U D D E R
M O V I N G
R U D D E R
M O V I N G
F L T C T R L
A S T B Y ?
NO
WTRIS - TRAINING INFORMATION POINT - SMYD BITE - SERVO TEST
YES
YES
YES
YES
YES
YES
YES
YES
1
1 BITE SHOWS INIT NOT COMPLETE
IF INITIALIZATION IS NOT COMPLETE
T E S T
I
F A L E D
S
P A S E D
T E S T
MENU
(FAULT 1)
YES
D E L
T A I S ?
M O R E
OR
O
S E R V
T E S T ?
PUSH YES FOR
MORE DETAILS
MENU
NO
- 107 -

27-24-00
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General
This page is for reference.
WTRIS -- SMYD 2 - SYSTEM SUMMARY
WTRIS -- SMYD 2 - SYSTEM SUMMARY
- 108 -

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WTRIS - SMYD 2 - SYSTEM SUMMARY
L ADIRU
SMYD 2
LVDT
STANDBY RUDDER PCU
R ADIRU
28V DC
28V DC
28V AC
EHSV
SOLENOID VALVE
FLT CTRL A AND B
YD ENGAGE SWITCH
IR DATA
YAW DAMPER
ENGAGE SWITCH
YAW DAMPER
ENGAGE LIGHT
OFF/STBY
ON/OFF
YD ENGAGE
COMMAND
YD ENGAGE
INTERLOCK
YD ACTUATOR
POSITION
WTRIS AND
ADR DATA
IR DATA
STBY YD
NOTE:
THIS DIAGRAM SHOWS SMYD 2
INTERFACES FOR WTRIS AND
STANDBY YAW DAMPING ONLY.
CW POS SENSOR (CAPT)
MCP
FMC
RA
RIGHT AOA SENSOR
FLAP POSITION
TE FLAP POSITION XMTRS
FLAPS UP/NOT UP
ANGLE OF ATTACK
CONTROL WHEEL INPUT
- 109 -

34-61-00
34-61-00-001.fm
General
The flight crew uses the flight management computer
system (FMCS) to enter route and vertical performance
flight plan data for a flight.
With ACARS, the FMC can receive flight plan data from a
ground station and can send flight status information
to a ground station.
With the flight plan and inputs from the airplane
sensors, the FMCS does these functions:
- Navigation
- Performance
- Guidance.
Navigation
A navigation data base is in the FMC memory. It
includes the navigation data for the area of operation.
The pilot can use the navigation data base to set the
entire flight plan before a flight.
The FMC calculates the airplane's lateral and vertical
position during the flight. The lateral position
calculation uses the inertial reference function and
the radio navigation aids, if available.
The FMC also uses the global positioning system (GPS)
data in the lateral position calculation.
The vertical position calculation uses the air data
reference function and the inertial reference function
data.
The FMC compares the calculated position with the
flight plan for LNAV and VNAV control. The FMC shows
the calculated position and the flight plan on the
navigation display.
Performance
A performance data base in the FMC contains data to
model the airplane and the engines. The flight crew
puts this data in the FMC:
- Airplane gross weight
- Cruise altitude
- Cost index.
The FMC uses the data to calculate these functions:
- Economy speeds
- Best flight altitude
- Top of descent point.
The common display system (CDS) shows target speeds and
altitudes.
Guidance
The FMC sends commands to the digital flight control
system (DFCS) and the autothrottle function (A/T). The
DFCS and the A/T use these signals to control the
FLIGHT MANAGEMENT COMPUTER SYSTEM -- INTRODUCTION
- 110 -

34-61-00
34-61-00-001.fm
airplane in the lateral (LNAV) and vertical (VNAV)
modes of flight.
Built-In Test Equipment
You use the FMCS CDU to select and control BITE for
these systems:
- FMCS
- Digital flight control system (DFCS)
- Autothrottle (A/T)
- Air data inertial reference unit (ADIRU)
- Common display system (CDS)
- Electronic engine controller (EEC)
- APU engine control unit (ECU)
- Fuel quantity indication system (FQIS).
AA - autoflight status annunciator
act - active
ACARS - aircraft communications addressing and
reporting system
ACMS - airplane conditioning monitoring system
ADIRS - air data inertial reference system
ADL - airborne data loader
ADS - automatic dependent surveillance
AFN - ATS facility notification
A/I - antice
alt - altitude
ANP - actual navigation performance
appr - approach
APU - auxiliary power unit
ARINC - aeronautical radio incorporated
arr - arrival
ASA - autoflight status annunciator
ASIC - application specific integrated circuit
A/S - airspeed
A/T - autothrottle
ATA - actual time of arrival
ATC - air traffic control
ATS - air traffic services
att - attitude
baro - barometric
BCS - backcourse
BIT - built in test
BITE - built in test equipment
brg - bearing
C - celsius
calc - calculate
cap - capture
CAPT - captain
CAS - computed airspeed
CCA - circuit card assembly
CDU - control display unit
cg - center of gravity
- 111 -

34-61-00
34-61-00-001.fm
CI - cost index
CIAP - common instrument approach procedures
clb - climb
clr - clear
CLK - clock
cmd - command
chng - change
CO - company
com - communication
comp - complete
CON - continuous
config - configuration
CP - control panel
CPU - central processor unit
CRC - cyclic redundancy check
crs - course
crz - cruise
ctr - center
DA - drift angle
DB - data base
DBL - data base loader
DC - direct current
del - delete
dep - departure
des - descent
dest - destination
dev - deviation
DFDAU - digital flight data acquisition unit
DIR - direct
dist - distance
DLDR - data loader
dsply - display
DTG - distance-to-go
DME - distance measuring equipment
DU - display unit
E - east
ECS - environmental control system
E/O - engine out
econ - economy
ECU - engine control unit
EDFCS - enhanced digital flight control system
E/D - end of descent
EEC - electronic engine control
EEPROM - electrically erasable programmable read
only memory
EFCP - EFIS control panel
EFIS - electronic flight instrument system
EGPWC - enhanced ground proximity warning
computer
EGPWS - enhanced ground proximity warning system
ELEX - electronics
eng - engine
ENG - engaged
EO - engine out
ETA - estimated time of arrival
ETE - estimated time enroute
- 112 -

34-61-00
34-61-00-001.fm
ETO - estimated time overhead
EXEC - execute
F - fahrenheit
FAC - final approach course
FANS - future air navigation system
FCC - flight control computer
F/D - flight director
FDAU - flight data acquisition unit
FF - fuel flow
FL - flight level
flt - flight
FMA - flight mode annunciation
FMCS - flight management computer system
F/O - first officer
FPA - flight path angle
FQIS - fuel quantity indicating system
FQPU - fuel quantity processor unit
frq - frequency
ft - feet
fwd - forward
G - ground
G/A - go-around
GLS - GNSS landing system
GMT - Greenwich mean time
G/P - glidepath
GPS - global positioning system
GPSSU - global positioning system sensor unit
GPWC - ground proximity warning computer
GPWS - ground proximity warning system
GRWT - gross weight
G/S - glideslope
GS - ground speed
hdg - heading
HIRF - high intensity radiation field
HDOP - horizontal dissolution of precision
HF - high frequency
HIL - horizontal integrity limit
H/L - high/low
hld - hold
hrdw - hardware
HSI - horizontal situation indicator
H/W - hardware
IAN - integrated approach navigation
ICAO - International Civil Aviation
Organization
ident - identification
IFR - instrument flight rules
IFSAU - integrated flight system accessory unit
IGS - instrument guidance system
ILS - instrument landing system
inbd - inboard
info - information
INOP - inoperative
inti - initialization
INIT/REF - initialization/reference
INTC - intercept
- 113 -

34-61-00
34-61-00-001.fm
I/O - input/output
IRS - inertial reference system
ISA - international standard atmosphere
ISB - intersystem bus
isol - isolation
JAA - Joint Airworthiness Authority
kgs - kilograms
KTS - nautical miles per hour (knots)
L - left
LAAS - local area augmentation system
lat - latitude
LBS - pounds
LCD - liquid crystal display
LDA - localizer directional aid
LED - light emitting diode
lim - limit
LNAV - lateral navigation
LOC - localizer
long - longitude
LRC - long range cruise
LVL CHG - level change
M - meters
mag - magnetic
MAGVAR - magnetic variation
MAINT - maintenance
MASI - mach airspeed indicator
max - maximum
Mbyte - megabyte
MCDU - multi-purpose control display unit
MCP - mode control panel
MDA - minimum descent altitude
MEDB - model/engine data base
MHZ - megahertz
MIN - minimum
MLS - microwave landing system
MMO - maximum operating mach number
MMR - multi-mode receiver
MNVR - maneuver
mod - modification
msg - message
Mword - megaword
N - north
N1 - low pressure compressor/turbine speed
N2 - high pressure compressor/turbine speed
N/A - not appliacble
nav - navigation
NAV RAD - navigation radio
NCD - no computed data
ND - navigation display
NDB - navigation database
NM - nautical miles
norm - normal
NPS - navigation performance scales
NV - non volatile
OAT - outside air temperature
OFP - operational flight program
OFST - offset
- 114 -

34-61-00
34-61-00-001.fm
OPC - operational program configuration
OPT - optimum
PDB - performance data base
PDL - portable data loader
perf - performance
PFD - primary flight display
pln - plan
pos - position
PPOS - present position
pred - predicted
preflt - preflight
proc - procedure
prof - profile
PROG - progress
PROM - programmable read only memory
P/S - power supply
PSEU - proximity switch electronics unit
PTH - path
QCS - quiet climb system
QFE - altimeter setting to show altitude above
reference airfield
QNE - standard day, sea level altimeter
setting
QNH - altimeter setting to show altitude above
mean sea level
QUAD - quadrant
qty - quantity
R - right
RA - radio altitude
rad - radio
RAIM - receiver autonomous integrity monitor
RAM - random access memory
RCF - rear connector filter
RCVR - receiver
RDY - ready
REC - recorder
RED - reduced
ref - reference
RF - radio frequency
RNAV - area navigation
RNP - required navigation performance
RTA - required time of arrival
rte - route
R/W - read/write
RW - runway
rwy - runway
S - south
S/C - step climb
SAT - static air temperature
SATCOM - satellite communications
SDF - simplified directional facility
SDI - source destination identifier
sel - select
SID - standard instrument departure
SPD - speed
SRAM - scratch random access memory
srce - source
- 115 -

34-61-00
34-61-00-001.fm
SSM - sign status matrix
sta - station
STAR - standard terminal arrival route
STD - standard
SUPP - supplemental
SW - software
s/w - software
SWDL - software data loader
TACAN - tactical air navigation
TAI - thermal antice
TAS - true airspeed
TAT - total air temperature
TBC - The Boeing Company
T/C - top of climb
T/D - top of descent
T/R - thrust reduction
tgt - target
thr - thrust
thr ref - thrust reference
TMA - thrust mode annunciation
TO - takeoff
TO/GA - takeoff/go-around
trans - transition
trk - track
TRU - true
UPD - update
UTC - universal time (coordinated)
V1 - takeoff decision speed
VR - takeoff rotation speed
V2 - engine out safe climb speed
v - volt
V - volt
VANP - vertical actual navigation performance
VFR - visual flight rules
VMO - maximum operating velocity
VNAV - vertical navigation
VOR - VHF Omnidirectional range
VREF - reference speed
VRNP - vertical required navigation performance
VSD - vertical situation display
V/S - vertical speed
VSI - vertical speed indicator
VTK - vertical track
W - west
wpt - waypoint
wt - weight
WTAI - wing thermal antice
XFR - transfer
xmtr - transmitter
XTK - cross track
Z - zulu
ZFW - zero fuel weight
- 116 -

34-61-00
34-61-00-001.fm
FLIGHT MANAGEMENT COMPUTER SYSTEM - INTRODUCTION
40
AIRPLANE
SYSTEMS
CONTROL DISPLAY
UNIT
FLIGHT MANAGEMENT
COMPUTER
APPROACH
ILS
AND ALTITUDES
OPTIMIZED SPEEDS
TAKEOFF
MARKER
OUTER
WAYPOINT
TOP OF
DESCENT
COURSE
ALTERATION
WAYPOINT
CRUISE
TOP OF
CLIMB
STEP
CLIMB
CLIMB
ORIGIN
GUIDANCE
WAYPOINT
DESTINATION
NAVIGATION DISPLAY
HDG MAG
090
GS357 TAS338
336o/15
GRH
D838.4z
32.5NM
12
15
18
MPB
T/D
GRH
YKM
ELN
VOR 1
116.00
DME35.1 FMC L
VOR 2
ELN
DME28.5
- 117 -

34-61-00
34-61-00-002.fm
General
The flight management computer system (FMCS) controls
the airplane navigation, performance and guidance
functions. This decreases the work load of the flight
crew . It also gives access to the BITE functions of
other systems.
The FMCs get data from other airplane systems to
calculate navigation and performance data. This data
shows on the common display system (CDS) for use by the
flight crew.
The navigation and performance function data is used by
the guidance sub-function in the FMC. The guidance sub-
function outputs are sent to the enhanced digital
flight control system (EDFCS). This data gives
automatic or manual control of the airplane flight path
in the vertical (VNAV) and lateral (LNAV) modes. This
is the guidance function of the FMC.
FMC display data goes directly to CDS. Present position
data goes directly to the air data inertial reference
units (ADIRU). The ADIRUs use present position during
the alignment.
All other data goes through two transfer relays to the
user systems.
The FMC input and output data format is ARINC 429
digital data and analog discretes.
FMCS -- GENERAL DESCRIPTION
FMCS -- GENERAL DESCRIPTION
- 118 -

34-61-00
34-61-00-002.fm
FMCS - GENERAL DESCRIPTION
AIRPLANE SENSORS
- ANTI-ICE
- ENGINE BLEED AIR
- AIR/GROUND LOGIC
- FUEL QUANTITY
PROCESSOR UNIT
- DME
- ILS
- VOR
- DFCS MODE CONTROL
- AUTOTHROTTLE
SYSTEM
PANEL
EFIS CONTROL
PANEL DISCRETES
COMMON DISPLAY SYSTEM
GREENWICH
MEAN TIME
(GMT)
ELECTRONIC CLOCK
DATA LOADER
RADIO NAVIGATION
SYSTEMS
AUTOFLIGHT SYSTEMS
LOAD FMC DATA
ADIRU
POSITION AND
AIR DATA
FMC (2)
PWR
ON VALID
FMC
CDU (2)
CDS
ADIRU
DFCS
AUTOFLIGHT STATUS
ANNUNCIATOR
TRANSFER
RELAY (2)
DISPLAY DATA
NAV DATA
FMC
NORMAL
ON R
ON L
BOTH BOTH
FMC SOURCE
SELECT SWITCH
ACARS
VHF NAV/DME CONTROL
AUTOTUNE DATA
SMYD
AIRPLANE GROSS
WEIGHT
CDS
MODE ANNUNCIATION
FUEL QUANTITY PROCESSOR
UNIT
BITE DATA
PANEL
AUTOTUNE DATA
DME
FDAU
POSITION DATA
GPWC
TRACK & PRESENT
POSITION DATA
DOWN LOAD FMC DATA
DATA LOADER
STEERING COMMANDS
THRUST COMMANDS
EDFCS
- 119 -

34-61-00
34-61-00-093.fm
P9 Forward Electronics Panel
These are the FMCS components on the P9 forward
electronics panel:
- CDU 1
- CDU 2.
P5 FWD Overhead Panel
The FMC source select switch is on the P5-28 forward
overhead panel.
P61 Panel
These are the FMCS components on the P61 panel:
- Airborne data loader
- Data loader control panel.
FMCS -- FLIGHT COMPARTMENT COMPONENT LOCATION
FMCS -- FLIGHT COMPARTMENT COMPONENT LOCATION
- 120 -

34-61-00
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FMCS - FLIGHT COMPARTMENT COMPONENT LOCATION
P9 FWD ELECTRONICS PANEL
- CDU 2
- CDU 1
AIRBORNE DATA LOADER (P61)
DATA LOAD SELECTOR
L
CAPT
UPR
R
F/O
LWR
SYSTEM SELECT
NORMAL
CDU
C
SINGLE SYS
FMC
DATA LOADER CONTROL PANEL (P61)
FLIGHT COMPARTMENT
(LOOKING AFT)
FMC SOURCE SELECT SWITCH (P5)
FMC
BOTH
BOTH
NORMAL
ON L ON R
- 121 -

34-61-00
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FMCS - Component Location - Electronic Equipment Shelf
These are the FMCS components on the E5-2 shelf:
- FMC 1
- FMC 2
- FMCS program switch modules
- FMCS transfer relay 1
- FMCS transfer relay 2.
FMCS -- ELECTRONIC EQUIPMENT COMPARTMENT LOCATIONS
FMCS -- ELECTRONIC EQUIPMENT COMPARTMENT LOCATIONS
- 122 -

34-61-00
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FMCS - ELECTRONIC EQUIPMENT COMPARTMENT LOCATIONS
ELECTRONIC EQUIPMENT COMPARTMENT
FMC 1
TRANSFER
TRANSFER
FMC 2
RELAY 2
RELAY 1
(SHOWN
REMOVED)
FWD
FMCS PROGRAM
SWITCH MODULES
(BEHIND PANEL)
E5-2 SHELF
- FMC 1
- FMC 2
FWD
- 123 -

34-61-00
34-61-00-005.fm
General
The FMC and CDU primary power is 115v ac from the AC
standby bus and AC transfer bus 2.
FMCS -- FMC AND CDU POWER INTERFACE
FMCS -- FMC AND CDU POWER INTERFACE
- 124 -

34-61-00
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FMCS - FMC AND CDU POWER INTERFACE
P18-2 CIRCUIT BREAKER
PANEL
CDU 2
FMC
FMC
CDU 1
115V AC
STBY BUS 1
115V AC
XFER BUS 2
115V AC
XFER BUS 2
P6-1 CIRCUIT BREAKER
PANEL
CMPTR 2
CMPTR 1
115V AC
STBY BUS 1
CDU 1
POWER SUPPLY
FMC 1
CDU 2
FMC 2
LAMP TEST
5V AC PANEL
LAMP TEST
28/14V DC
BRIGHT/DIM
LIGHTING
28/14V DC
BRIGHT/DIM
5V AC PANEL
LIGHTING
HIGH/LOW
VOLTAGE POWER
SUPPLIES
HIGH/LOW
VOLTAGE POWER
SUPPLIES
POWER SUPPLY
- 125 -

34-61-00
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General
The transfer relays are Ledex type relays. They
mechanically latch to the position you select.
The FMCS source select switch controls the FMCS
transfer relays. These are the switch positions:
- NORMAL
- BOTH ON L (both on left FMC)
- BOTH ON R (both on right FMC).
Operation
The transfer relay power is 28v dc from electronics bus
2. The FMC source select switch controls the dc power
to the transfer relays.
With the FMC source select switch in the NORMAL
position, both transfer relays go to the normal
position and mechanically latch in that position.
When the FMC source select switch is set to the BOTH ON
R position, 28v dc goes from the source select switch,
through a contact on transfer relay 2, to relay 1 coil
winding. Relay 1 moves to the BOTH ON R position and
mechanically latches to that position. Relay 2 does not
change because the BOTH ON R and NORMAL positions are
the same.
When the FMC source select switch is set to the BOTH ON
L position, 28v dc goes from the source select switch,
to the coil on relay 1. Relay one latches in the BOTH ON
L/NORMAL position. The FMC source select switch then
sends 28v dc through a contact on transfer relay 1 to
the relay 2 coil winding. Relay 2 moves to the BOTH ON
L position and mechanically latches to that position.
Other contacts on the transfer relays supply the
necessary logic to tell these LRUs the position of the
transfer relays:
- DEU (1&2)
- FDAU
- FMC (1&2).
You use the FMCS BITE on the ANALOG DISCRETES page 3/4
to do a check of the FMC source selection.
FMCS -- TRANSFER RELAY POWER INTERFACE
FMCS -- TRANSFER RELAY POWER INTERFACE
- 126 -

34-61-00
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FMCS - TRANSFER RELAY POWER INTERFACE
ON R
BOTH
FMCS TRANSFER
RELAY 1
RELAY 2
FMCS TRANSFER
P5-28 FMC SOURCE
SELECT SWITCH
ELEX
POWER 2
28V DC
FMCS XFER
P6-1
FMC
ON R
BOTH
ON L
BOTH
NORMAL
BOTH
ON L
FMC SOURCE
SELECT SWITCH
DEU 2
FMC 2
FMC 1
FDAU
DEU 1
FMC SOURCE
IFSAU
BOTH ON R
/NORMAL
BOTH ON R
/NORMAL
BOTH ON L BOTH ON L
SELECT
FMC SOURCE
SELECT
FMC SOURCE
SELECT
FMC SOURCE
SELECT
NORMAL
FMC SOURCE
SELECT
- 127 -

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