Q400-Landing Gear 1

12.13 (ATA 32) LANDING GEAR

12.13.1 Introduction

The Dash 8-Q400 landing gear is electrically controlled and hydraulically operated. Hydraulicallyoperated nosewheel steering gives directional control during taxiing, take-off and landing. Eachmain wheel has hydraulically powered anti-skid brakes. There is also an emergency/park brakesystem.

12.13.2 General

The tricycle gear is a retractable dual wheel installation. The main gears retract aft into thenacelles and the nose gear retracts forward into the nose section. Doors completely enclose thelanding gear when it is retracted and partially enclose the gear when it is down.

A Power Transfer Unit (PTU) supplies back-up hydraulic power to the No. 2 hydraulic system. Ifthe landing gear cannot be extended normally, there is an alternate landing gear extensionmethod.

Advisory lights show position of gear doors and downlocks. There is also an alternate downlockverification system. An aural warning sounds if the gear is not extended during certain landingconfigurations.

A Proximity Sensor Electronics Unit (PSEU) monitors and controls the operation of the landinggear components. The nosewheels are steerable by a flight deck hand control and by the rudderpedals.

The wheels may be equipped (customer option) with tire fill pressure gauges for quick visualmeans of verifying tire pressure during aircraft walk-around.

The main wheels are equipped with anti skid multiple disc brakes. The brakes can be controlledby the brake pedals or the EMERG BRAKE lever.

Dash8 - Q400 - Landing Gear

Page 1

Figure 12.13-1 Landing Gear


Page 2

12.13.3 Controls and Indications - Landing Gear and Brakes


Page 3

Figure 12.13-2 Nose Gear Ground Lock Control Handle

PRESS BUTTONTO RELEASEPULL AND TURNTO GROUND LOCKNOSE GEAR

PR

ES

S B

UT

TO

NT

O R

EL

EA

SE

PU

LL

AN

D T

UR

NT

O G

RO

UN

D L

OC

KN

OS

E G

EA

R

1 2

1 2

ENGAGED(FULLY EXTENDED)

DISENGAGED(FULLY RETRACTED)


Page 4

NOSE GEAR GROUND LOCK CONTROL HANDLE CALLOUTS

1. NOSE GEAR GND LOCK CONTROL HANDLE PUSHBUTTON (momentary action)PUSH - releases nose gear control handle from fuselage- control handle only springs out partly- control handle must be pulled out fully from sprung out position to rotate

2. NOSE GEAR GND LOCK CONTROL HANDLE (two position, rotary action)IN - (flush with fuselage)- nose gear unlocked

OUT - (not rotated)- nose gear downlock disengaged- handle must be rotated to engage downlock

OUT - (rotated clockwise)- nose gear downlock engaged- control handle must be pulled out fully from sprung out position to rotate


Page 5

Figure 12.13-3 Landing Gear Control Panel

LANDING GEAR

LOCKRELEASE

DN UP

TEST

MUTEHORN

N. DOORL. DOOR R. DOORRIGHTNOSELEFTRIGHTNOSELEFT

1

2

4

5

3

6


Page 6

LANDING GEAR CONTROL PANEL CALLOUTS

1. GEAR DOOR ADVISORY LIGHTS

(L. DOOR, N. DOOR, R. DOOR) segment (amber) - related hydraulic gear door open- hydraulic gear doors stay open with no hydraulic pressure

(L. DOOR, N. DOOR, R. DOOR) segment (blank) - related hydraulic gear door closed- hydraulic gear doors close after normal gear extension and retraction

2. LANDING GEAR SAFE ADVISORY LIGHTS

LEFT, NOSE, RIGHT segment (green) - related gear down and locked- lights can be tested using CAUT / ADVSY LIGHTS toggle switch- gear can also be checked with downlock verification lights

LEFT, NOSE, RIGHT segment (blank)- related gear not down and locked or in uplock position

3. LANDING GEAR UNSAFE ADVISORY LIGHTS

LEFT, NOSE, RIGHT segment (red) - related gear not locked up or down

LEFT, NOSE, RIGHT segment (blank ) - related gear locked up or down or no power to lights

4. SELECTOR LEVER LOCK BUTTON (momentary action)PUSH DOWN AND HOLD - enables operation of landing gear handle

5. LANDING GEAR SELECTOR LEVER/LIGHT (two position)

UP - starts landing gear retraction sequence

DN - starts normal landing gear extension sequence- also select DN for alternate gear extension- No Smoking signs come on automatically if not on

HANDLE (amber)- landing gear operation does not agree with position of landing gear selector handle

6. LANDING GEAR WARNING HORN MUTE/TEST SWITCH (two position, momentary action)

TEST - gear warning tone sounds over flight deck speakers

HORN MUTE - gear warning tone is silenced under certain configurations


Page 7

Figure 12.13-4 Landing Gear Alternate Release Door and Inhibit Switch

ARE CLEAR OF OBSTRUCTIONSBEFORE CLOSING ACCESS PANEL

ENSURE ALL WHEEL WELLS

TO CLOSE DUMP VALVE

CAUTIONLANDING GEAR

ALTERNATE RELEASE

OPEN DOOR FULLY

INHIBIT

NORMAL

DOOR OPENDOOR CLOSED

1

A

A

INHIBIT

NORMAL

3

2


Page 8

LANDING GEAR ALTERNATE RELEASE DOOR CALLOUT1. LANDING GEAR ALTERNATE RELEASE DOOR (two position)

CLOSED - landing gear extends and retracts normallyOPEN - connects hydraulic extension and retraction lines to return- gear cannot be extended using normal hydraulic power- door must stay open for alternate gear extension

2. MAIN L/G RELEASE HANDLE (spring loaded to stowed position)PULL - make sure the handle is pulled fully (all the way out)- releases main gear hydraulic doors and main gear uplocks- hydraulic gear doors will stay open

3. LANDING GEAR INHIBIT SWITCH (guarded, two position toggle switch)INHIBIT - disables normal landing gear extension operation using the LANDIN GEAR lever- LDG GEAR INOP caution light comes on (if not already on)NORMAL - landing gear extends and retracts normally


Page 9

Figure 12.13-5 Landing Gear Alternate Extension Door

LANDING GEAR ALTERNATE EXTENSION

OPEN OVERHEADDOOR FIRST

PULL RING TOOPEN PANEL

TO EXTEND AND LOCK MAIN LANDING GEAR,OPERATE HAND PUMP UNTIL HANDLE IS STIFF.

NOSE L/G RELEASE

PULL FULLY UP

VISUAL CHECK FOR GEAR DOWN & LOCKEDTURN ON LIGHT SWITCHCHECK FOR LIGHTS

ACCESS DOOROPEN

ACCESS DOORCLOSED

5

4

1 FWD

A

A

B

C

B C

3

2

5

4


Page 10

LANDING GEAR ALTERNATE EXTENSION DOOR CALLOUTS

1. LANDING GEAR ALTERNATE EXTENSION DOOR (two position)

CLOSED - landing gear extends and retracts normally

OPEN - alternate extension hydraulic fluid available for alternate gear extension- door must stay open for alternate gear extension

2. NOSE GEAR RELEASE HANDLE (spring loaded to stowed position)

PULL - make sure the handle is pulled fully (all the way out)- releases nose gear doors and nose gear uplocks- hydraulic gear doors will stay open

3. MAIN GEAR ALTERNATE EXTENSION HAND PUMP (two position)- pumps fluid from the emergency hydraulic reservoir to the auxiliary main landing gear

actuators- handle located behind copilot's seat is inserted into socket

4. LANDING GEAR DOWNLOCK VERIFICATION SWITCH (two position, toggle switch)

AFT - activates alternate downlock verification system on each gear- enables operation of gear verification lights

CENTER - alternate downlock verification system deactivated

5. LANDING GEAR DOWNLOCK VERIFICATION LIGHTS(NG, LH, RH) (green)- related (Nose, Left main, Right main) landing gear is down and locked using the alter-

nate downlock verification system- downlock verification toggle switch must be set aft

(NG, LH, RH) - (blank)- related (Nose, Left main, Right main) landing gear is not down and locked using the

alternate downlock verification system- downlock verification toggle switch not set aft


Page 11

Figure 12.13-6 Anti Skid Switch

C-FJOE

1


Page 12

ANTI SKID SWITCH CALLOUT

1. ANTI SKID SWITCH (three position, momentary at TEST)

TEST - held in position and released to ON position- if airborne with gear down and locked, INBD ANTISKID and OUTBD ANTISKID caution

lights come on for 3 seconds then go off to show serviceable anti skid system- if on the ground, INBD ANTISKID and OUTBD ANTISKID caution lights come on for 6

seconds and then go off to show serviceable anti skid system- if antiskid test fails, INBD ANTISKID or OUTBD ANTISKID caution lights will stay on

ON - anti skid system activated- anti skid self test is made when switch is first moved to position and if wheel speed is not

more than 17 knots- INBD ANTISKID and OUTBD ANTISKID caution lights go out

OFF - anti skid system deactivated- INBD ANTISKID and OUTBD ANTISKID caution lights come on


Page 13

Figure 12.13-7 Emergency/Parking Brake Lever Call-outs

PROP F

L

A

P

S

900

900

MAX1020

MIN850

START &FEATHER

FUELOFF

0

5

10

15

351 2

0

0

0

0

0

CONTROL

LOCK

RATING

P

ER

EMERG

BRAKE

ELEVATOR

TRIM

TO

RATING

CONTROL

LOCK

FLIGHTIDLE

MAXREV

PARK

ND

NU

OFF

ON

1 2

OFF

ON

WO

21


Page 14

EMERGENCY/PARKING BRAKE LEVER CALLOUTS

1. EMERGENCY/PARKING BRAKE LEVER PUSHBUTTON (momentary action)

PUSH - lets parking brake lever be released from PARK detent

2. EMERGENCY/PARKING BRAKE LEVER (two position)

FORWARD - emergency brake not engaged- pull back to actuate emergency brake- pull back to engage detent for park brake- uses No. 2 hydraulic pressure or accumulator pressure- a fully charged accumulator is sufficient for approximately six applications

PARK (detent)- parking brake set if parking brake hydraulic pressure is correct- PARKING BRAKE caution light comes on- minimum 500 psi parking brake pressure is required to ensure adequate park brake

pressure before engine start- hand pump located in right main wheel well can be used to increase park brake system

pressure- alternatively, if an AC power supply is available, park brake system pressure can be

increased by running the SPU and the PTU


Page 15

Figure 12.13-8 MFD Parking Brake Hydraulic Pressure

27.728.5

27.728.526.126.1

ELECTRICAL AC EXTPOWER

DC EXTPOWER

LOAD1 1 51 1 51 1 5

. 06

. 06

. 06

1 1 51 1 51 1 5

. 06

. 06

. 06

ABC

ABC

+22+22+22

+1. 00- . 34- . 34

+1. 00

+1. 00 . 06

+1. 00 +1. 00

APU GEN

DC GENLOAD1 2

TRULOAD1 2

LOADBATT

C

VOLTDC BUS

RL

MAINAUX

STBY

ESSMAINSEC

AC GEN 1

AC GEN 2

VOLT LOAD

VOLT LOAD

HYD PRESS HYD QTYPK

STBYPSI x 1000 % x 100

BRK 1 2 3 1 2 34

2

FLAPDEG

1050

35

0 0

1


Page 16

MFD CALLOUT PERTAINING TO LANDING GEAR

1. PK BRK INDICATOR - hydraulic pressure in the emergency/parking brake system- normally the same as No 2 hydraulic system pressure- shows brake accumulator pressure if No 2 hydraulic system pressure is not available- minimum 500 psi is required if Engine no.2 is started first

minimum 1000 psi is required if Engine no. 1 is started first- pressure shown in psi- indicates from 0 to 4000 in 1000 psi increments- in composite mode, hydraulic brake pressure shown digitally


Page 17

Figure 12.13-9 Nosewheel Steering Toggle SwitchPILOTS SIDE PANEL CALLOUTS PERTAINING TO STEERING1. NOSEWHEEL STEERING SWITCH (two position, toggle)

STEERING - nosewheel steering activated if aeroplane is on ground and nosewheel is within70 of center- NOSE STEERING caution light will illuminate if a fault is detected in the Nosewheel

Steering system.OFF - nosewheel steering deactivated and is in the castor mode- nosewheel assumes shimmy damped or castor mode- use when tow bar is connected to nose gear- NOSE STEERING caution light comes on if there is hydraulic pressure in the steering

system

CIR BKR LIGHT

W/S WIPERICE DETECT

PILOTSFLT PNL

PROP O'SPEEDGOVERNOR

OFF

LIGHT

ADCTEST 1

TEST 2 TEST 2

OFF BRT

STALL WARN TEST 1

OFF

STEERING

OFF

TEST

T/O WARNTEST

1


Page 18

Figure 12.13-10 Nosewheel Steering Hand Control

NOSEWHEEL STEERING HAND CONTROL CALLOUTS

1. STEERING HAND CONTROL (rotatable control, self centering)- rotate left or right to steer nosewheel up to 70 either side of center- nosewheel STEERING toggle switch must be set to STEERING- spring loaded to center position

2. STEERING RANGE LABEL (decal)- shows forward steering range or for steering hand control- can be used for reference with mark on steering hand control

GRD CREW FWD AFT

GPWS FLAP OVERRIDE

F W ARD

OR

STEERING RANGE

1 2


Page 19

Figure 12.13-11 Brake Pedals

BRAKE PEDAL CALLOUTS

1. BRAKE PEDALS (differential action)

PUSH - top of pedals for brakes- left pedal for left brake- right pedal for right brake

2. RUDDER PEDALS ADJUSTMENT HANDLE (rotary action)

ROTATE - moves both pedals forward or aft

Right side shown. Left side similar.


Page 20

12.13.4 Landing Gear - Description

The main gear retracts aft and has multiple disc brakes with an anti skid system (Figure 12.13-12). The nose gear retracts forward and has steerable nosewheels (Figure 12.13-13). The land-ing gear is operated by the No. 2 hydraulic system and is controlled by the landing gear selectorlever on the LANDING GEAR control panel. There is an alternate (emergency) means of exten-sion for the main and nose landing gear. Advisory lights give extension/retraction and fail/safeinformation.

Each main gear has a pair of forward and aft doors hinged to the nacelle side structure (Figure12.13-14). When the gear is up, all doors enclose the main wheels. With the main gear down, theforward door on each main gear stays open. The nose gear has a pair of forward and aft doors,which completely enclose the nose gear when the gear is up (Figure 12.13-15). With the geardown, the forward nose doors are closed, while the aft doors stay open.

The Proximity Sensor Electronic Unit (PSEU) controls the landing gear, hydraulically operatedgear doors and related advisory lights. It also monitors Weight-on-Wheels (WOW) sensors.WOW signals prevent gear retraction while on the ground. Failure of a WOW system turns on aWT ON WHEELS caution light. Redundancy is built in to ensure landing gear operation if there isa PSEU failure. An audible warning tone sounds, when the gear is not down and locked withlanding flap or power settings.

Ground lock pins are supplied for the main gear and an integral ground lock mechanism is con-trolled from outside the aeroplane for locking the nose gear. The main gear lock-pins may bekept in the forward compartment of the forward passenger door. With the gear extended, the pinsare inserted into the main gear stabilizer brace assemblies (Figure 12.13-16).

There are also landing gear door lock pins for the nose (Figure 12.13-17) and main (Figure12.13-18) hydraulic doors. This prevent the hydraulic gear doors from closing.


Page 21

Figure 12.13-12 Main Landing Gear Assembly

RE

MO

VE

BE

FO

RE

FL

IGH

T

LEGEND

1. Shock Strut. 2. Drag Strut. 3. Stabilizer Brace. 4. Main Gear Pin. 5. Auxiliary Actuator. 6. Main Actuator. 7. Fairings. 8. Proximity Sensors.

FWD

1

2

3

4

5

6

7

8


Page 22

Figure 12.13-13 Nose Gear Landing Gear Assembly

11

12

FWD

1

2

3

4

5

6

7

NOTE

Left nosewheel removedfor clarity.

LEGEND

1. Downlock Actuator. 2. Upper Drag Strut. 3. Lower Drag Strut. 4. Taxi Light. 5. WOW Cover. 6. Tow Assembly. 7. Trailing Arm.

8. Retraction Actuator. 9. Steering Gearbox.10. Outer Cylinder.11. Centering Actuator.12. Piston Assembly.

10

8

9


Page 23

Figure 12.13-14 Main Landing Gear Extended Doors Open

NOTE

Left gear shown.Right gear similar.

FWD


Page 24

Figure 12.13-15 Nose Landing Gear Extended and Retracted

FWD

FWD

CLOSED

OPEN

1

5

2 3

4

LEGEND

1. Forward Door.2. Forward Door Operating Mechanism.3. Shock Strut Assembly.4. Aft Door.5. Aft Door Actuating Linkage.


Page 25

Figure 12.13-16 Main Gear Ground Lock Pin

A

A

MAIN LANDINGGEAR

B

B

2

1

LEGEND

1. Lock Pin.2. Lock Pin Hole.

FWD

FWD


Page 26

Figure 12.13-17 Nose Gear Hydraulic Door Lock Pin

TRONAIRRE

MO

VE

NOTE

View shown with debris guard removed.


Page 27

Figure 12.13-18 Main Gear Hydraulic Door Lock Pin

TRONAIRRO

VEC

ONTA

COX

EM

NOTE

Right side shown.Left side similar.


Page 28

12.13.4.1 Gear Operation

Landing gear operation is controlled and monitored from the LANDING GEAR control panel,adjacent the Engine Display (ED). The landing gear is selected UP or DN (down) by moving thelanding gear selector lever. A LOCK RELEASE selector lever must be held down to let the gearselector lever move in either direction.

An alternate downlock verification system confirms downlock engagement if the primary down-lock indication is in doubt. Three green downlock verification lights are located under the LAND-ING GEAR ALTERNATE EXTENSION panel in the flight deck floor.

Gear Warning Tone

A landing gear warning tone sounds over the flight compartment speakers if the HORN switch isheld at TEST. It also sounds if the gear is not down and locked and:

1. flaps > 8.5 either engine torque < 50% both PLA < RATING detent

2. both PLA < FLIGHT IDLE +12 KIAS < 156

RA < 1053 ft (321 m) if it is valid

3. one PLA < FLIGHT IDLE + 12 both PLA < RATING detent HORN switch not latched at MUTE KIAS < 156 RA < 1053 ft (321 m) if it is valid

NOTE: This is the only case in which the landing gear warning tone may be muted. Enginefailure at airspeed less than 156 KIAS.


Page 29

Figure 12.13-19 Landing Gear Retraction Schematic

CO

NT

RO

LS

EQ

UE

NC

ING

MA

IN/N

OS

EG

EA

R A

ND

DO

OR

PO

SIT

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S

WE

IGH

T-O

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LO

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PR

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SIN

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IMIT

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EN

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IN/N

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EG

EA

R A

ND

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ES

NO

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AR

AS

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MB

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MA

IN G

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SS

EM

BLY

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CR

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YS

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MS

GE

AR

PO

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ION

AN

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CK

ED

IN

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AT

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LA

ND

ING

GE

AR

LO

CK

RE

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AS

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ST

HO

RN

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DO

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L.

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R.

DO

OR

RIG

HT

NO

SE

LE

FT

RIG

HT

NO

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LE

FT D

NU

P MU

TE


Page 30

Retraction Sequence

When the landing gear selector lever is selected to the UP position, hydraulic pressure from No.2 system is applied to the retract side of the system (Figure 12.13-19). This opens the nose gearforward doors and retracts the nose gear, it also opens the main gear aft doors and retracts themain gear. The aft nose gear doors are mechanically linked and close with the retracting nosegear. After nose gear retraction, the forward nose gear doors close hydraulically. The forwardmain gear doors are mechanically linked and close with the retracting main gear. After main gearretraction, the aft main gear doors close hydraulically.

The advisory light sequence during retraction starts with the LEFT, NOSE and RIGHT red unsafelights and the amber selector handle light coming on. At the same time, the green LEFT, NOSEand RIGHT lights go off to show the gear is not locked down. The amber door advisory lightscome on to show the hydraulically operated gear doors are open. When the landing gear isretracted and locked in the up position, the amber selector handle light and red advisory lights goout. Finally, the amber gear door advisory lights go out to show all the hydraulic gear doors haveclosed. No advisory lights should be on if the gear is up correctly. The main and nose gear areheld in the up position mechanically with uplocks, and hydraulic pressure is removed from thesystem.

Extension Sequence

When the landing gear selector lever is moved to the DN position, hydraulic pressure is appliedto the extend side of the system through the solenoid selector valve (Figure 12.13-19). The mainand nose hydraulic doors open, and the main and nose gear extend. The hydraulic forward noseand aft main gear doors close after the gear is down and locked.

The advisory light sequence during extension starts with the LEFT, NOSE, and RIGHT redunsafe lights and the amber gear selector handle light coming on. The amber door advisorylights then come on to show the hydraulically operated gear doors are open. When the landinggear is fully extended and locked in the down position, the red unsafe lights, and the selectorhandle light goes out. Then the green LEFT, NOSE, and RIGHT advisory lights come on. Finally,the gear door advisory lights go out when the hydraulically operated doors are closed. Continu-ous hydraulic pressure acts on the gear when down and locked, however primary downlock is bythe overcenter locks.

If a landing gear hydraulic sequencing valve fails, or the PSEU is unable to control it, the LDGGEAR INOP caution light comes on.

NOTE: With the LDG GEAR INOP caution light on, ALTERNATE GEAR EXTENSION proce-dure is to be followed.


Page 31

Figure 12.13-20 Alternate Landing Gear Extension Schematic

LA

ND

ING

GE

AR

AL

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RN

AT

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EL

EA

SE

DO

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(O

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N)

MA

IN D

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PU

MP

NO

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GE

AR

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NO

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LO

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Page 32

12.13.5 Alternate Gear Extension

The alternate extension system (Figure 12.13-20) gives a means of extending the landing gearwhen:

LDG GEAR INOP caution light is on Landing gear indication fails Loss of No. 2 hydraulic system pressure

The landing gear extension INHIBIT switch is installed in the flight deck ceiling, adjacent to themain LANDING GEAR ALTERNATE RELEASE door. Setting the switch to INHIBIT isolates allhydraulic pressure from the landing gear system.

When the main LANDING GEAR ALTERNATE RELEASE door on the flight deck ceiling isopened it mechanically opens a bypass valve in the normal hydraulic extension system, andgives access to the MAIN L/G RELEASE handle. Pulling the handle releases the main landinggear doors and uplocks. The main gear will free fall but may not fully extend. The LANDINGGEAR ALTERNATE EXTENSION door, on the flight deck floor, must then be fully opened givingaccess to the alternate extension handpump and the NOSE L/G RELEASE handle. Opening thedoor mechanically operates the MLG alternate selector valve. If the MLG does not reach thedown and locked position, the extension pump handle, located behind the copilot, is inserted intothe pump handle socket and operated to complete main gear extension and subsequent down-lock (Figure 12.13-21). Both the LANDING GEAR ALTERNATE EXTENSION door and the MAINLANDING GEAR ALTERNATE RELEASE door must be left fully open after alternate landinggear extension.

When the NOSE L/G RELEASE handle is pulled, the nose gear uplock and doors are releasedand the nose gear free falls to a down and locked position, assisted by the airflow to a down andlocked position.


Page 33

Figure 12.13-21 Main Landing Gear Alternate Extension System

SU

CT

ION

LIN

E

LE

GE

ND

A

MLG

ST

AB

ILIZ

ER

BR

AC

E A

SS

EM

BLY

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T N

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PA

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Left G

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sim

ilar.


Page 34

Figure 12.13-22 Nosewheel Steering Schematic

NOSESTEERING

fs number

LOW SPEED TAXI MODE70 LEFT AND RIGHT

(STEERING CONTROL HANDLE)

HIGH-SPEED TAXI MODE8 LEFT AND RIGHT(RUDDER PEDALS)

UNPOWERED(CASTER) MODE

120 LEFT AND RIGHT

8 8

7070

120 120

OFF

STEERING

PSEU

NOSEWHEELSTEERING

CONTROL UNIT(SCU)

STEERINGMOTOR

ON-GROUNDSIGNAL FROMNOSE GEARWEIGHT ON

WHEELS SWITCHESCAUTION LIGHT

STEERINGACTUATOR

NOSEWHEELSTEERING SWITCH

RUDDERPEDALS

STEERINGCONTROLHANDLE

LEGEND

No. 2 Hydraulic Pressure.Steering Pressure.ReturnElectrical


Page 35

12.13.6 Nosewheel Steering System

Directional control on the ground is by the nosewheel steering (NWS) system (Figure 12.13-22),powered by the No. 2 hydraulic system. Steering control is by either the Steering Hand Control orthe rudder pedals. The Steering Hand Control turns the nosewheel up to 70 either side of centerfor low speed taxi. Steering with the rudder pedals turns the nosewheel up to 8 either side ofcenter for high-speed taxi, take-off and landing roll. After take-off, the nosewheel automaticallycenters before retraction.

The hand control, located on the Pilots Side console, is self-centering and operates when theSTEERING switch is set to the STEERING position. The nosewheel must be within 70 of centerfor the steering to work. An index mark on the hand control shows the relative position of thenosewheel against a fixed STEERING RANGE decal. With the STEERING switch set to STEER-ING, power is directed to the nosewheel Steering Control Unit (SCU), if the nose gear is downand locked with weight-on-wheels.

The nosewheel will revert to a passive shimmy dampened castoring mode if:

The nosewheel angle is greater than 70 The SCU detects a failure STEERING switch is set to OFF

In the passive mode, the nosewheel will castor up to 120 either side of center. Differential brak-ing and/or power may be used for directional control in the passive mode.

The NOSE STEERING caution light comes on if:

SCU detects a failure with STEERING switch set to STEERING hydraulic pressure detected in steering system with STEERING switch set to OFF

The NOSE STEERING caution light does not come on if electrical power is removed from theSCU.

When taxiing in reverse the STEERING switch must be selected on. However, no steering is per-mitted with either the tiller or the rudder pedals.

NOTE: Nosewheel steering using the hand control is limited to forward taxiing only, with theSTEERING switch set to the STEERING position.

CAUTION: Do not set the STEERING switch to STEERING if tow bar is connected to nose gear.


Page 36

Figure 12.13-23 Normal Brake System

OU

TB

D

AN

TIS

KID

INB

D

AN

TIS

KID

LE

GE

ND

Ele

ctrica

lM

ech

anic

al

Norm

al B

raki

ng P

ress

ure

(N

o.1

Sys

tem

)E

merg

ency

Bra

king M

ete

red P

ress

ure

Hyd

raulic

Retu

rn P

ress

ure

QU

AN

TIT

Y L

IMIT

ING

VA

LV

ES

(4

)

CO

PIL

OT

RU

DD

ER

PE

DA

LS

Fro

m H

ydra

ulic

Sys

tem

NO

. 2

WH

EE

LS

PE

ED

SE

NS

OR

(4

)T

RA

NS

DU

CE

RS

SH

UT

TL

EV

AL

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S (

4)

RIG

HT

MA

IN

BR

AK

EC

ON

TR

OL

VA

LV

E

PS

EU

CA

UT

ION

&W

AR

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F

To

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lic R

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ydra

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NO

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)

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CO

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AN

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Page 37

12.13.7 Brake System

12.13.7.1 Normal Braking

Each main wheel is equipped with a multiple disc brake unit powered by the No. 1 hydraulic sys-tem (Figure 12.13-23). An Anti Skid Control Unit (ASCU) modulates the application of brakepressure to each brake unit.

Brake pressure is applied by pushing the pilots or copilots brake pedals (Figure 12.13-25).

The anti skid control unit:

Monitors wheel speed Modulates the brake pressure applied to each brake unit to prevent wheel lock-up Gives maximum braking at all levels of runway friction.

The ANTI SKID switch on the copilot's glareshield panel operates the anti skid system when setto the ON position and the wheel speed is more than 10 knots. A start up self test of the anti skidcontrol circuits is made when the switch is moved to the ON, or momentary TEST. The start upself test is prevented with wheel speed more than 17 knots. If the ANTI SKID switch is held atTEST, the aeroplane on the ground, the INBD ANTISKID and the OUTBD ANTISKID cautionlights come on for six seconds and then go out. If the ANTI SKID switch is held at TEST in the air,with the landing gear extended and locked, will turn on the related caution lights for three sec-onds. If the ASCU senses a fault in the system, it turns on the related caution light.

The PSEU supplies weight-on-wheels and gear up and locked signals to the ASCU, to makesure that the brakes are off until the aeroplane has touched down and the wheels are spinning. Inconditions of low runway friction, the main gear wheels may not spin up before the aeroplane'sweight is fully on the wheels. In this case, the ASCU gives a 5 second delay before brake pres-sure is applied. This delay is immediately cancelled when wheel speed is more than 35 knots.

NOTE: Brake cooling times must be observed between a landing, or a low energy rejectedtake-off and a subsequent take-off, to make sure that sufficient brake energy is avail-able to bring the aeroplane to a complete stop if the subsequent take-off is rejected.


Page 38

Figure 12.13-24 Brake Pedals

1

2

3

45

6

7

8

9

10

FWD

LEGEND

1. Copilot Brake Pedals. 2. Tie Rods. 3. Brake Control Levers. 4. Brake Interconnect Cables. 5. Lever Springs. 6. Cables to Brake Control Valve. 7. Push Rods. 8. Spring Rods. 9. Tie Rods.10. Pilot Brake Pedals.


Page 39

12.13.8 Emergency Brake System

The emergency/parking brake system (Figure 12.13-25) lets the brakes be applied if the normalbrake system fails, or for setting the parking brake. An EMERG BRAKE lever on the Engine Con-trol quadrant operates the system. The emergency/parking brake system is powered by No. 2hydraulic system, or by parking brake accumulator pressure. Hydraulic pressure to the emer-gency/parking brake system is shown on the PK BRK indicator on the PERMANENT SYSTEMSAREA (PSA) of the MFD.

The EMERG BRAKE lever operates against a spring to produce a resistance proportional to thebrake pressure applied as the lever is pulled back. There is no differential braking and no antiskid protection when using the EMERG BRAKE lever. If the emergency/parking brake system isused with No. 2 hydraulic system inoperative, the accumulator supplies brake pressure. A fullycharged accumulator is sufficient for approximately six applications.

The parking brake is engaged by pulling the EMERG BRAKE lever all the way back to the detentPARK position. This turns on the PARKING BRAKE caution light on the Caution and Warningpanel. The button on the side of the handle must be pushed to release the lever from the PARKdetent.

NOTE: Care should be taken when releasing the lever as considerable spring tension willforce the lever forward.

NOTE: With the parking brake set, application of engine power will cause the take-off warn-ing horn to sound.

A hand pump located in the right main wheel well can be used to increase the park brake systempressure. Minimum pressure required before engine start is 500 psi.

Alternatively, if an AC power supply is available, park brake system pressure can be increasedby running the SPU and the PTU.


Page 40

Figure 12.13-25 Emergency Brake System

FLAPDEG

35

1050 HYD PRESS HYD QTY

PKSTBY

PSI x 1000 % x 100

BRK 1 2 3 1 2 34

2

0

High PressureNitrogen

Parking Brake / Emergency Pressure

No. 2 HydraulicSystem Suction

PARKINGBRAKE

#2 MFD

From No. 2System Reservoir

From No. 2Hydraulic System

ACCUMULATORGAUGE

HAND PUMP

CAUTION LIGHT

MAIN WHEELBRAKE UNITS


SHUTTLEVALVES

To the otherMain Gear

NOTEShown with ParkingBrake applied.

EMERGENCY/PARKINGBRAKE CONTROL VALVE

ACCUMULATOR

(Right Nacelle)

No. 2 Hydraulic Systemor

Accumulator Pressure

HandPump

Pressure


Hydraulic Return


Page 41

12.13.9 Tires

12.13.9.1 Tire Fill Valve Gauges

Tire pressure gauges are offered as a customer option, to operators who want a visual means ofchecking tire pressures during a walk-around. The dial gauge is integral with the inflation valveand mounted in the same location on the wheel without any additional installation requirements.

A gauge is mounted on each MLG and NLG wheel and has a dial face with a shaded portion ofits face denoting the proper inflation pressure plus a 5% tolerance.

The gauge itself uses a Bourdon tube with the closed end attached to a pointer and the other endvented to the tire interior through the inflation valve bore.

12.13.9.2 Tire Inspection (Removal criteria)

General

Dunlop tires fitted to Q400 has two layers of nylon fabric placed between the casing plies andthe base of the tread grooves. This Inter Tread Fabric (also called reinforcement fabrics) formspart of the wearable tread pattern and will be exposed during the life of the tread. (Ref Figure12.35.26.)

Examine the tires for signs of wear, damage and other deterioration.

1) Wear

Remove the tire when tread has worn to the base of any grove or if any casing plies areexposed.

Note: Tires found to be exhibiting the above removal wear standard, which at the time is atan out-station, the replacement can be postponed to first night stop or to the basewhichever comes first.

2) Cuts or cracking

a) Tread

Remove tire if any cut or crack penetrate any casing plies.

Remove tire if cracking undercuts ribs.

Remove tire if any cut extend more than 35 mm or 50% of any tread rib and has a treaddepth of 50% or more than existing tread depth.

b) Sidewall

Remove tire if cracking is found in the sidewall.

Note: If only the first casing ply is damaged, the replacement of the tire can be postponedto the first night stop or to base whichever comes first.

3) Bulges or Air Bubbles

Remove tires if bulges or air bubbles are found in the tread or in the sidewall.

Note: Removal of tires exhibiting above removal standard may be postponed to the firstnight stop or to base whichever comes first.


Page 42

Figure 12.13-26 Tire


Page 43

Q400-Landing Gear 1

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