NOSE
NOSE
DOOR
SWITCHING
NOSE
GEAR
SELECTOR
VALVES
LEFT
G
RIGHT
LDG GEAR
UP
NOSE
GEAR
DN LCK
REL
THROTTLE
LEVER
IDLE
SWITCHES
UPLOCK
NOSEWHEEL NOSEWHEEL
STEERING
STEERING
POWER
SUPPLY
DN
CABIN
LOW
PRESS
RELAY
DOWNLOCK 1
MUTE
HORN
TEST
DOWNLOCK 2*
FULLY EXT
PROX
SWITCHES
WOW 1
MAIN
GEAR
SELECTOR
VALVES
FLAP
CONTROL
UNIT
WOW 2
RIGHT
MAIN
GEAR
AURAL
WARNING
ANTI-SKID
GEAR
CONTROL
NO SMOKING
UPLOCK
LEFT
MAIN
GEAR
FASTEN SEAT BELTS
DOWNLOCK 1
DOWNLOCK 2
AIR/
GROUND
PROX
SWITCHES
WEIGHT
ON
WHEELS
WOW 1
WOW 2
UPLOCK
DOWNLOCK 1
LANDING GEAR
CONTROL UNIT
DOWNLOCK 2
PROX
SWITCHES
WOW 1
WOW 2
Challenger 601
July 1995
ANTI-SKID
ELECTRIC POWER
HYDRAULIC POWER
AURAL WARNING
ANTI-SKID
FLIGHT GUIDANCE
INTERCOM
APR
THRUST REVERSER
SPOILERS
AIR CONDITIONING
STALL PROTECTION
CABIN PRESSURIZATION
COCKPIT HEAT
WOW
OP FAIL
WOW
IP FAIL
*MICROSWITCH
Developed for Training Purposes
4-155
Landing Gear/Brakes/Steering
Landing Gear Control and Indication
CAE SimuFlite
Weight-on-Wheels System
WEIGHT ON WHEELS (WOW)
DC
BUS 1
WOW
CHAN 1
CB-A74
WOW
CHAN 1
LEFT
MAIN 1
CB-A162
BATT
BUS
RIGHT
MAIN 1
PS
PS
PS
PS
ON GROUND
WOW
CHAN 2
CB-B162
DC
BUS 1
LEFT
MAIN 2
WOW
CHAN 2
RIGHT
MAIN 2
CB-B74
WEIGHT ON WHEELS — INPUT
FMS / EFIS / FGC / WX RADAR
APR 1
LH THRUST REVERSER
HYD PUMP 1
SPOILERS 1
ELEC SYSTEM (ADG) 1
AIR CONDITIONING 1
CABIN PRESS 1
TAKE OFF CONFIG WNG
ELEC SYSTEM (UTILITY BUS)
FLIGHT GUIDANCE COMPUTER 1
ANTI SKID (INBD)
STALL PROT. TEST
STALL PROT. 1
STALL PROT 2
ANTI SKID (OUTBD)
COCKPIT HEAT
INTERCOM
CABIN PRESS 2
AIR CONDITIONING 2
ELEC SYSTEM (ADG) 2
SPOILERS 2
HYD PUMP 2
RT THRUST REVERSER
APR 2
FLIGHT GUIDANCE COMPUTER 2
FMS / EFIS / FGC
NOSE
WOW 1
LEFT MAIN
WOW 1
RIGHT MAIN
WOW 1
ON GROUND
RIGHT MAIN
WOW 2
10 SEC DELAY
WOW
OP FAIL
WOW
IP FAIL
MASTER
CAUTION
LEFT MAIN
WOW 2
NOSE
WOW 2
PROXIMITY
SWITCH (TYP.)
(SIMPLIFIED)
4-156
Developed for Training Purposes Challenger 601
July 1995
Landing Gear/Brakes/Steering
Landing Gear Control Unit
L.G. TEST SWITCH
O/P FAIL TEST
FMS / EFIS / FGC / WX RADAR 1
APR 1
LH THRUST REVERSER
HYD PUMP 1
SPOILERS 1
ELECT. SYSTEM (ADG) 1
AIR CONDITIONING 1
CABIN PRESS 1
WOW
CHAN 1
CB-A74
DC
BUS 1
WOW
CHAN 1
CB-A162
POWER
SUPPLIES
TAKE OFF CONFIG. WNG.
ELECT. SYSTEM (UTILITY BUS)
BATT
BUS
STALL PROTECTION
FLIGHT GUIDANCE COMPUTER 1
ANTI SKID (INBD)
15 SEC DELAY
STALL PROT. TEST
WOW
OP FAIL
WOW
IP FAIL
MASTER
CAUTION
STALL PROT. 1
STALL PROT. 2
ANTI SKID (OUTBD)
COCKPIT HEAT
INTERCOM
ON GROUND
CABIN PRESS. 2
AIR CONDITIONING 2
WOW
CHAN 2
POWER
SUPPLIES
CB-B162
DC
BUS 2
WOW
CHAN 2
CB-B74
ELECT. SYSTEM (ADG) 2
SPOILERS 2
FMS / EFIS 2
RT THRUST REVERSER
BATT
BUS
NOTE: ALL CONTACTS SHOWN ARE
PART OF COMPARATOR CIRCUIT
& DO NOT AFFECT THE OUTPUTS
TO OTHER SYSTEMS
APR 2
FLIGHT GUIDANCE COMPUTER 2
HYD PUMP 2
(TYPICAL) PWR
FROM
W.O.W
CIRCUIT
Challenger 601
July 1995
TO
HYDRAULIC
SYSTEM
Developed for Training Purposes
4-157
CAE SimuFlite
4-158
Developed for Training Purposes Challenger 601
July 1995
Landing Gear/Brakes/Steering
Landing Gear and Brakes
The landing gear system consists of trailing link main landing
gear and a conventional nose landing gear. All gear have nitrogen-charged shock absorber struts with dual wheels and tires.
Normally, No. 3 hydraulic system pressure retracts and extends
the gear. If an electrical, mechanical, or No. 3 hydraulic system
fault occurs, a manually actuated emergency extension system
mechanically releases the uplock actuators, dumps hydraulic
pressure, and allows the gear to free fall by gravity. A down and
locked condition is assisted by a combination of airflow and
spring pressure on the nose gear and downlock assist actuator
on each main gear, powered by the No. 2 hydraulic system.
Each main gear wheel has mechanically operated and
hydraulically powered carbon composite brakes with anti-skid
protection. Normally, No. 3 hydraulic system supplies the
inboard brakes while the No. 2 hydraulic system supplies the
outboard brakes. If the normal braking system fails (i.e., loss of
hydraulic system pressure), a braking accumulator stores sufficient pressure for approximately six braking applications.
An electronically controlled (steer by wire), hydraulically operated nosewheel steering system positions the nose gear during
ground operations in response to rudder pedal or pilot’s handwheel movement.
Challenger 601
July 1995
Developed for Training Purposes
4-159
CAE SimuFlite
Weight-on-Wheels System
The landing gear control unit consists of a gear control and No.
1 and No. 2 weight-on-wheel channel. The unit receives inputs
from:
■
nose and main gear downlocks
■
nose gear oleo switch
■
nose and main gear uplocks
■
main gear proximity switches (two per landing gear leg)
■
nose gear proximity switch and microswitch.
The gear control channel, depending on the position of the
landing gear, then supplies outputs for the:
■
nose and main gear retract and extend solenoids
■
landing gear safe indicators
■
landing gear unsafe indicator
■
landing gear handle downlock solenoid
■
horn mute indicator
■
aural warning system
■
■
fasten seat belts and no smoking signs
nosewheel steering system.
The No. 1 and 2 WOW channels operate independently but are
interconnected to prevent false gear indications from a single
channel affecting an aircraft system. The two channels, in turn,
control the operation of various aircraft systems (see Table 4-M).
If a landing gear proximity switch malfunctions and provides a
different indication from the others, the landing gear control unit
illuminates the WOW I/P (input) FAIL light after a 10-second
delay. If a WOW channel output differs from the rest, the WOW
O/P (output) FAIL light illuminates after a 10-second delay. The
WOW O/P FAIL light also illuminates the WOW light on the 8channel annunciator panel and the MASTER CAUTION lights.
4-160
Developed for Training Purposes Challenger 601
July 1995
Landing Gear/Brakes/Steering
No. 1 WOW System
No. 2 WOW System
Air conditioning
Air conditioning
Air-driven generator
Air-driven generator
Aural warning
Automatic power reserve
Automatic power reserve
Cabin pressurization
Autopilot
Cockpit heating
Cabin pressurization
Intercom
Cockpit heating
No. 2 Stall warning system
Ground spoilers
No. 2B pump interlock
Inboard anti-skid
Outboard anti-skid
Left thrust reverser
Right thrust reverser
No. 1 stall warning system
Spoilers
No. 1B pump interlock
Table 4-M; Weight-on-Wheels System
Retraction
When the landing gear struts extend after takeoff, the WOW
system proximity switches indicate an in-air condition. With
these inputs, the landing gear control unit releases the control
handle solenoid lock.
Moving the handle to the UP position with a weight-on-wheels
signal not present begins the landing gear retraction sequence.
The nose landing gear door selector valve shifts to the open
position while the main landing gear selector valve shifts to the
retract position. No. 3 hydraulic system pressure then flows
through the priority and selector valves to the nose gear door
and main gear uplock actuators. The nose gear doors begin
opening and the main gear uplocks move to the unlocked position. The NOSE DOOR OPEN light illuminates, the NOSE,
LEFT, and RIGHT lights extinguish, and the gear unsafe light
flashes.
Challenger 601
July 1995
Developed for Training Purposes
4-161
CAE SimuFlite
When the nose gear doors completely open, the nose gear
selector valve shifts to the retract position, the downlock actuator releases, and the nose gear drag brace unlocks.
Hydraulic pressure to the retract side of the nose and main gear
actuators unlocks the main gear downlock actuators and drives
the landing gear into their wheel wells.
As the gear reaches the up and locked position, the uplocks
mechanically latch to hold the gear in the retracted position.
Operation of the uplocks then provides a gear retracted and
locked indication to the nose gear door selector valve and the
landing gear control unit. The door selector valve then directs
pressure to close the nose gear doors. At the end of the retraction sequence, the nose gear, nose gear door, and main gear
selector valves shift to the neutral position. The NOSE DOOR
OPEN and gear unsafe lights then extinguish.
Extension
Moving the landing gear control handle to the DN position
begins the extension sequence by energizing the nose gear
door and main gear selector valves. The nose gear doors open.
The nose gear selector valve shifts to the extended position;
the uplocks release. Hydraulic pressure then flows to the
extend side of the landing gear actuators. The NOSE DOOR
OPEN light illuminates and the red gear unsafe light flashes.
Hydraulic pressure to the extend side of the landing gear actuators drive the gear legs to the extended position. When gear
reaches the fully extended position, the mechanical nose gear
drag brace and main gear actuator downlocks engage.
The NOSE, LEFT, and RIGHT lights illuminate and the gear
unsafe light extinguishes. The nose gear door selector valve
shifts to close the nose gear doors. The NOSE DOOR OPEN
light extinguishes.
4-162
Developed for Training Purposes Challenger 601
July 1995
Landing Gear/Brakes/Steering
Emergency Extension
If the normal landing gear extension system fails (i.e., hydraulic
system fails, electrical fault, etc.), pulling the L.G. PULL handle
up unlocks the nose gear doors, releases the nose gear
uplocks, and operates the nose gear dump valves. The nose
gear begins extending under its own weight assisted by
springs.
Further movement of the handle releases the main gear
uplocks and operates the gear dump and main gear assist
selector valves. The landing gear extends under its own weight
assisted by actuators powered by the No. 2 hydraulic system.
Gear Warning
Retarding the throttles to idle with one of the landing gear not
down and locked sounds the landing gear warning horn.
Pressing the MUTE HORN pushbutton silences the horn and
illuminates the button’s amber light. Advancing a throttle above
idle extinguishes the light.
Extending the flaps past 30° without the gear being extended
also sounds the landing gear warning horn. The horn cannot be
silenced by pressing the MUTE HORN button with the flaps
past 30°.
Brakes
All main landing gear wheels have carbon composite, multiple
disc brakes operated hydraulically by two separate hydraulic
systems. No. 2 hydraulic system pressure supplies the outboard brakes while No. 3 system pressure supplies the inboard
brakes.
Challenger 601
July 1995
Developed for Training Purposes
4-163
CAE SimuFlite
Normal Braking
Pressing on a pair of toe brakes mechanically actuates the dual
brake control valve spools. The spools shift to meter hydraulic
fluid proportional to pedal effort through the anti-skid control
valves and hydraulic fuses to the brake assemblies. The brake
assembly pistons extend under pressure to force a pressure
plate against the rotating and stationary discs.
With release of braking pressure, the brake control valves shift
to direct hydraulic pressure to the system’s return line.
Anti-Skid
With the ANTI-SKID switch in the ARM position, the parking
brake off, and the nose gear down and locked, the anti-skid
system arms and begins monitoring wheel speed for an incipient skid.
When the aircraft is airborne (wheel-off-wheels), the system’s
locked wheel detector circuit arms. Because the wheels are not
spinning, the system sees a locked wheel condition and dumps
all braking pressure through the anti-skid control valves. This
feature prevents landing with the brakes applied.
At touchdown the WOW switches actuate to provide an onground indication to the skid control unit. Wheel spin-up above
35 kts then overrides the WOW switch signal to provide immediate braking and anti-skid protection.
During the landing roll and taxi above 10 kts, the skid control
system monitors main wheel deceleration and compares it to a
reference signal. If a wheel’s deceleration exceeds the reference signal, indicating an incipient skid, the skid control unit
signals the skidding wheel’s anti-skid control valve to momentarily reduce braking pressure and prevent a wheel skid.
The reduced braking pressure allows wheel spin up until it
matches the others. After an incipient skid, the skid control unit
modulates braking pressure to all wheels below the skid level.
4-164
Developed for Training Purposes Challenger 601
July 1995
OUT
LEFT
INBD
FUSE
ANTI-SKID
VALVE
ANTI-SKID
VALVE
FUSE
METERING
VALVE
PILOT
BRAKE
PEDALS
R
PARKING
METERING
VALVE
L
Developed for Training Purposes
LEFT
OUTBD
TEST
ANTI-SKID
ARM
Challenger 601
January 1999
IN
0 X PSI
0
1000
3
2
1
ACCUMULATOR
3
2
1
BRAKE
Brake System
L
BRAKE
ANTI-SKID
VALVE
METERING
VALVE
RN
LL &
TU
PU
RIGHT
INBD
COPILOT
BRAKE
PEDALS
FUSE
ANTI-SKID
VALVE
METERING
VALVE
R
OUT
3
2
1
ACCUMULATOR
IN
0 X PSI
0
1000
RIGHT
OUTBD
FUSE
PARKING
SHUT OFF
BRAKE
3
2
1
BRAKE
4-165
Landing Gear/Brakes/Steering
4-166
November 1997
Developed for Training Purposes Challenger 601
10 KT
Anti-Skid Profile
WHEEL
SPIN-DOWN
30-35 KT
CAE SimuFlite
WEIGHT ON
WHEELS
OR
WHEELS SPIN-UP
30-35 KT
WEIGHT
OFF
WHEELS
TOUCHDOWN
PROTECTION
LOCKED WHEEL
PROTECTION
ANTI-SKID
OFF
NOTE:
TO TEST ANTI-SKID
WHEEL SPEED MUST
BE BELOW 17 KNOTS
NORMAL ANTI-SKID
PROTECTION
Landing Gear/Brakes/Steering
Above 30 kts groundspeed, the anti-skid system’s locked wheel
protection also provides basic anti-skid protection if a skid
occurs. As groundspeed drops below 10 kts, the system deactivates.
Pressing the anti-skid TEST button for two to four seconds with
the aircraft below 17 kts groundspeed enables a complete test
of the anti-skid system. Illumination of the INBD FAIL and
OUTBD FAIL lights during testing indicates normal system
operation. If a system component fails with the TEST button
pressed, the associated light fails to illuminate. After releasing
the button, illumination of the INBD FAIL or OUTBD FAIL light
indicates a system malfunction. Releasing the anti-skid TEST
button prematurely may result in a false failure indication.
Parking Brake
After applying both toe brakes, pulling the PARKING BRAKE
handle out and rotating it 90° applies the parking brake by
mechanically operating the brake control valves. The control
valve’s spools shift and trap hydraulic pressure in the inboard
braking system supply lines.
Pulling the PARKING BRAKE handle also illuminates the parking brake ON light, closes the parking brake shutoff valve, and
de-energizes the anti-skid system relays.
Applying the toe brakes and rotating the PARKING BRAKE
handle 90° releases the parking brakes by mechanically
unlocking the brake control valves. After unlocking the parking
brake, stow the handle, then release the toe brakes. The ON
light extinguishes.
The parking brake should be set from the pilot’s seat. Although
the system allows either set of brake pedals to set the parking
brake, it may not be physically possible to depress the pedals
sufficiently to set the brake and reach across the center
pedestal to set the handle.
Challenger 601
November 1997
Developed for Training Purposes
4-167
CAE SimuFlite
Nosewheel Steering
Placing the N/W STEER switch in the ARMED position with the
landing gear down and locked and weight-off-wheels initiates
the nosewheel steering system self-test. If the system detects
an electrical or component fault, the NW STEER FAIL light illuminates; the system reverts to a free castoring mode that provides nosewheel shimmy dampening.
With weight-on-wheels and the N/W STEER switch in the
ARMED position, the nosewheel steering system electronic
control module (ECM) opens the steering selector valve.
Deflecting the rudder pedals and/or handwheel from neutral
actuates potentiometers connected to the ECM. The ECM, in
response to these steering signals, generates the necessary
commands to operate the steering control valve. The valve, in
turn, directs No. 3 hydraulic system pressure to the appropriate
side of the steering actuator. The actuator then mechanically
positions the nosewheel in the appropriate direction through a
pair of torque links that transfer steering action from the steering cuff to the nose wheels.
During towing, the torque links should not be disconnected; this
prevents damage to the nosewheel steering system. Nose
wheel steering must be selected OFF for towing.
When the nosewheel reaches the desired angle, its position
sensor provides a feedback signal to the ECM. The ECM then
commands the steering control valve to close both sides of the
steering actuator. This holds the nosewheel at the desired
angle.
4-168
Developed for Training Purposes Challenger 601
November 1997
Landing Gear/Brakes/Steering
Landing Gear
Power Source
No. 3 hydraulic system (normal)
No. 2 hydraulic system (assist)
Battery bus
DC Bus 1 and DC Bus 2
Control
Landing gear control handle
Gear control unit
Weight-on-wheels system
Downlock and uplock switches
L.G. PULL handle (emergency extension)
Monitor
Gear handle unsafe light
LEFT, NOSE, and RIGHT lights
NOSE DOOR OPEN light
Landing gear warning horn
Protection
Circuit breakers
Weight-on-wheels system
Brakes and Anti-Skid System
Power Source
No. 2 hydraulic system (inboard)
No. 2 hydraulic system (outboard)
Essential DC bus
DC Bus 1 and DC Bus 2
Control
Toe brake pedals
Brake control valves
Anti-skid system
Anti-skid TEST button
PARKING BRAKE handle
Monitor
Brake pressure gage
INBD FAIL and OUTBD FAIL lights
Parking brake ON light
Protection
Hydraulic fuses
Anti-skid system
Challenger 601
November 1997
Developed for Training Purposes
4-169
CAE SimuFlite
Nosewheel Steering
Power Source
No. 3 hydraulic system
DC Bus 1 and DC Bus 2
Control
Handwheel (±55°)
Rudder pedals (±7°)
N/W STEER switch
Electronic control module
Monitor
N/W STEER FAIL light
Protection
Weight-on-wheels system
Landing gear downlock switches
4-170
Developed for Training Purposes Challenger 601
November 1997