section - iii systems description - smartcockpithawker 800xp pro line 21 section iii - systems...

1Pilot’s Operating ManualOriginal Issue: Feb, 2002

Pro Line 21

Section - IIISYSTEMS DESCRIPTION

Sub-section 8LANDING GEAR

Table of Contents

Page

GENERAL ......................................................................................................8-3CONTROLS - ANNUNCIATORS - INDICATORS..........................................8-3

GEAR POSITIONS......................................................................................8-3Gear Locked Down ...............................................................................8-3Gear Unlocked ......................................................................................8-3Gear Locked Up....................................................................................8-3

STANDBY INDICATIONS............................................................................8-4Main Gear .............................................................................................8-4Nose Gear.............................................................................................8-4

WARNING HORN........................................................................................8-5LANDING GEAR SELECTOR and BAULK OVERRIDE...............................8-6

Figure 1 - Landing Gear Selector and Baulk Override ............................8-6RETRACTION and EXTENSION ...................................................................8-7

Figure 2 - Landing Gear Hydraulic System .............................................8-8MAIN GEAR ...................................................................................................8-9

WEIGHT-ON-WHEELS SWITCHES ...........................................................8-9NOSE GEAR ..................................................................................................8-9

NOSE GEAR BAY DOORS.........................................................................8-9Figure 3 - Main Landing Gear................................................................8-10Figure 4 - Nose Landing Gear ...............................................................8-11Figure 5 - Nose Gear Doors Release Strut ...........................................8-12

POWER SUPPLIES...................................................................................8-12AUXILIARY HYDRAULIC SYSTEM ............................................................8-13

LOWERING SEQUENCE ..........................................................................8-13Figure 6 - Auxiliary Hydraulic System....................................................8-14

WHEELS and BRAKES...............................................................................8-15LOCATION of CONTROLS and INDICATORS .........................................8-15MAIN WHEELS..........................................................................................8-15NOSE WHEELS ........................................................................................8-15WHEEL BRAKES ......................................................................................8-15

Normal System Operation...................................................................8-15Wheel Brake Lever .............................................................................8-15

Figure 7 - Wheel Brake Lever................................................................8-16

2 Pilot’s Operating ManualOriginal Issue: Feb, 2002


Hawker 800XP Pro Line 21Section III - SYSTEMS DESCRIPTION

Page

Figure 8 - Combined Hydraulic Pressure Indicator and Emergency Wheel Brake Annunciators................................ 8-17

Emergency System Operation with Main System Pressure Exhausted ..................................................... 8-17

POWER SUPPLIES .................................................................................. 8-18NOSE WHEEL STEERING.......................................................................... 8-18

OPERATION ............................................................................................. 8-18Figure 9 - Nose Gear Steering System................................................. 8-19

3Pilot’s Operating ManualRevision A2: Nov, 2004



GENERAL

The airplane has a hydraulically-powered retractable landing gear incorporating nitrogen charged shock absorber struts and nose wheel steering. Each main gear has two wheels and retracts inboard into wheel wells in the fuselage. Each main wheel well has a fairing attached to the landing gear and a hydraulically-operated door.

The nose gear has two wheels which retract forward into a bay with hinged doors and a fairing on the landing gear.

Hydraulic pressure is supplied from the main hydraulic system for the normal lowering and retraction of the gear. An auxiliary hydraulic system is provided for lowering the gear should the main hydraulic system or landing gear selection controls fail.

Details of the hydraulic system are provided in Sub-section 5 - HYDRAULICS.

CONTROLS - ANNUNCIATORS - INDICATORS

The gear position annunciators are located in a pyramid cluster on the center instrument panel to the right of the master warning system panel.

GEAR POSITIONS

Gear Locked Down

• Green annunciators illuminated

NOTE: The red GEAR annunciators are also illuminated when the gear selector lever is not in the down position with landing gear locked down.

Gear Unlocked

• Red annunciators illuminated

Gear Locked Up

• Both green and red annunciators extinguished

N GEAR

N GEAR

L GEAR

L GEAR

R GEAR

R GEAR

Gear Position Annunciators

4 Pilot’s Operating ManualRevision A2: Nov, 2004



STANDBY INDICATIONS

Main Gear

Standby main gear downlock indication is provided by an independent circuit connected to greenL GEAR and R GEAR annunciators located on the right side console.

Nose Gear

As the nose gear locks down, a mechanical post indicator extends from the top left of the center control pedestal.

Right Side Console

L GEAR R GEAR

Standby Main Gear Downlock Annunciators

L GEAR R GEAR

A RUDDER BIAS B

Upper Left AreaCenter Control Pedestal

Nose GearMechanicalPost Indicator

OAT

PUSH

Fuel Temp Switch




WARNING HORN

A warning horn sounds if the gear is not locked down when the flaps are extended beyond the 15°position. In this instance, the warning horn cannot be cancelled.

The warning horn will also sound if the gear is not locked down and either thrust lever is closed to obtain between 60% and 70% N1 RPM (nominal) with IAS below 150 kts. In this case, the warning horn can be cancelled by a switch on the forward side of the LH thrust lever. The audible warning is repeated if the second thrust lever is closed after a previous warning has been cancelled and not reinstated. The warning horn system resets when IAS is greater than 160 kts.

LEFT THRUST LEVER < 70%N1, > 60% N1

RIGHT THRUST LEVER > 70%N1, < 60% N1

PE BUSBAR

FLAPS 25° (SELECTED)

FLAPS 45° (NOT SELECTED)

GEAR POSITION SWITCH(MADE WHEN GEAR IS NOT LOCKED DOWN)

HORN

GEARWARNCTL

IAS < 150 KTS (RESETS WHEN IAS >160 KTS)

Gear Warning Horn Diagram




LANDING GEAR SELECTOR and BAULK OVERRIDE

A LANDING GEAR selector lever is provided to control the normal raising and lowering of the landing gear. The lever operates in a two-gated slot in the center instrument panel and is connected to a hydraulic selector valve located in the nose gear bay.

When the airplane is on the ground, a solenoid-operated pawl engages to lock the landing gear selector in the down position. At take-off, when the airplane weight comes off the wheels, the solenoid operates to withdraw the pawl allowing the selector lever to be moved away from the LANDING GEAR DOWN position. The pawl re-engages when the airplane lands.

The airplane has a LANDING GEAR BAULK OVRD PUSH button located next to the LANDING GEAR selector lever. If the Baulk fails to disengage when the airplane is airborne, pushing the button disengages the pawl. While the push button is pushed the landing gear selector can be moved to the up position.

CAUTION: THE LANDING GEAR BAULK OVRD CONTROL COULD BE OPERATED WHEN THEAIRPLANE IS ON THE GROUND. A WARNING THAT THE LANDING GEAR SELECTOR ISNOT IN THE DOWN POSITION IS PROVIDED BY ALL RED AND GREEN GEAR POSITIONANNUNCIATORS BEING ILLUMINATED AT THE SAME TIME.

SHOULD THIS WARNING BE IGNORED, A STEADY HORN AUDIBLE WARNING WILLSOUND IF THE ENGINE START PWR IS SELECTED.

Figure 1Landing Gear Selector and Baulk Override

CENTERINSTRUMENTPANEL




RETRACTION and EXTENSION (Figure 2)

With the weight of the airplane off the wheels, selecting LANDING GEAR up allows main hydraulic system pressure into the gear up pipelines. This pressure operates hydraulic jacks, one on each main gear, and one on the nose gear. Additionally, main pressure is routed via sequence valves and reversing valves to operate the two main gear wheel well door actuators.

Retraction sequence is as follows:

• Main gear wheel well doors open.

• Nosewheel steering isolated (nose wheel self-centers).

• Nose gear doors open.

• Nose gear locks up and doors shut.

• Main gear locks up.

• Wheel well doors shut and lock.

Subsequent LANDING GEAR down selection diverts main hydraulic system pressure to the gear down pipelines.

Extension sequence is as follows:

• Main and nose gears unlock and doors open.

• Main and nose gears lock down.

• Main gear wheel well doors shut but do not lock up.

• Nose gear doors shut.

• Nosewheel steering reconnects.

Main system pressure is dumped when the auxiliary hydraulic system is used to lower the landing gear.

In this case, the wheel well doors are pushed open by the extending main gear and remain open with the gear locked down.

-8 Pilot’s Operating ManualRevision A1: Nov, 2002



SHUTTLE

AUXILIARY

VALVE

SYSTEMHYDRAULIC

AUXILIARY

SYSTEMHYDRAULIC

AUXILIARY

SYSTEMHYDRAULIC

SHUTTLEVALVE

NOSEGEARACTUATOR

NOTE: For Auxiliary Hydraulic System,See Figure 6.

LANDINGGEARSELECTOR

DUMPVALVE

MAIN GEARACTUATOR

MAIN GEARACTUATOR

SEQUENCEVALVE

SEQUENCEVALVE

DOORACTUATOR

DOORACTUATOR

DIAGRAM SHOWS:LANDING GEAR SELECTED ‘UP’GEAR ‘UP’ PIPELINES

GEAR ‘DOWN’ PIPELINESVENTED TO RETURNDOOR ACTUATORS RETRACTED(DOOR CLOSED)GEAR ACTUATORS EXTENDED(GEAR UP)

FILTER

RESTRICTOR AND IN-LINE FILTERS

NON RETURN VALVE

MAIN SYSTEM PRESSURE TO RETURN

PRESSURIZED

Figure 2Landing Gear Hydraulic System




MAIN GEAR (Figure 3)

Each main oleo-pneumatic leg retracts inwards into a wheel well in the wing. The well is covered with the gear up by a fairing hinged to the wing, and linked to the gear. Additional fairing is provided by a wheel well door, hydraulically-actuated to shut when the gear locks up.

When the gear is selected down, the door opens until the gear locks down, then closes to cover the well. Each main gear is stabilized in the down position by a side stay located between the leg and the main wing structure. The side stay also forms the main locking component in both the extended and retracted positions.

WEIGHT-ON-WHEELS SWITCHES

Weight-On-Wheels (WOW) microswitch clusters are installed on the left and right gear. These switches provide control function to various circuits when the airplane is airborne or on the ground.

NOSE GEAR (Figure 4)

The self-centering nose landing gear retracts forward, and is faired in the up and down positions by two doors hinged to the nose structure and attached to the retracting mechanism. A small fairing attached to the rear of the landing gear completes the closure of the bay when the gear is retracted.

The oleo-pneumatic leg is attached to a fitting on each side of the nose gear bay, and is stabilized in the down position by a drag stay which also forms the main locking component in both the extended and retracted positions. A spring strut maintains the drag strut in the locked position.

The nose gear leg incorporates an attachment for towing purposes. When this attachment is used, the steering must be disconnected. A steering disconnect pin is located immediately under the towing pin hole.

NOSE GEAR BAY DOORS (Figure 5)

The door operating mechanism incorporates a release strut which allows the doors to be opened on the ground for access.

Access to the release strut when the doors are closed is via an aperture between the rear of the doors and the gear leg. The strut assembly consists of a lower and upper strut. To latch the doors closed, the upper strut telescopes into the lower and is retained by a hook engaging a pin. The hook is pivoted on and off the pin by a lever which is retained in the closed position by a spring-loaded latch.

When the lever is open, or not latched closed, a microswitch illuminates the N GEAR red annunciator to indicate the doors are either open or not correctly latched.

M6951_0 HA00C 017046AA.AI

N GEAR

N GEAR

R GEARL GEAR

CENTER INSTRUMENT PANEL

INDICATION OF NOSE GEAR DOORS OPEN OR UNLATCHED



Section III - SYSTEMS DESCRIPTIONHawker 800XP Pro Line 21

HYDRAULICACTUATOR

RETRACTION

DOORACTUATOR

Figure 3Main Landing Gear




Figure 4Nose Landing Gear

HYDRAULICRETRACTIONACTUATOR

STEERINGACTUATOR

STEERING DISCONNECT PIN(REMOVED WHEN TOWING AIRPLANE)




POWER SUPPLIES

DC power distribution is as follows:

PE Busbar

Normal landing gear position annunciators (6)

Warning horn control and warning horn

PS1 Busbar

Landing gear lever lock solenoid

PS2 Busbar

Standby landing gear downlock annunciators (2)

Figure 5Nose Gear Doors Release Strut




AUXILIARY HYDRAULIC SYSTEM (Figure 6)

The auxiliary hydraulic system is selected by pulling the AUX HYD SYSTEM handle. This action dumps any pressure in the normal landing gear system lines to the reservoir and isolates the auxiliary system from the main system return line.

It is not necessary to select the gear down in order to lower it. Operating the auxiliary system hand pump directs hydraulic fluid to the gear actuators via lines independent of the normal extension circuit.

LOWERING SEQUENCE

• The nose gear uplock is released, the nose bay doors open and the gear extends.

• The main gear uplocks are released, the wheel well doors are unlocked and the main gear extendspushing the doors open.

• As the nose gear locks down, the mechanical linkage closes the nose bay doors.

• When the main gear has locked down, the wheel well doors are left open.

Although it is not necessary to select the gear down when using the auxiliary system, it is recommended to do so after the gear has locked down, to avoid the possibility of a subsequent retraction of the gear when the airplane is on the ground. Selecting the gear down will also cancel the gear red annunciations.

The annunciations presented below are illuminated when the gear has been lowered via the auxiliary system, but the selector lever has not been moved to the down position.

M6951_0 HA00C 017046AA.AI

N GEAR

N GEAR

R GEARL GEAR

CENTER INSTRUMENT PANEL

INDICATION OF NOSE GEAR DOORS OPEN OR UNLATCHED




ON/OFF VALVE

LANDINGGEARSELECTOR

DUMPVALVE

RESERVOIR

LEVEL INDICATOR

FILTER

MAINGEARACTUATORS

SHUTTLEVALVE

KEY

AUXILIARYSYSTEM

MAINSYSTEM

SUCTION

RETURN

NOSEGEARACTUATOR

CIRCUIT SHOWN WITH SELECTOR HANDLE PULLED

MAINSYSTEM

FLAP CONTROLUNIT

AUX HYDLO LEVEL

Figure 6Auxiliary Hydraulic System

SHUTTLEVALVES

MWS PANEL




WHEELS and BRAKES

LOCATION of CONTROLS and INDICATORS

MAIN WHEELS

The main landing gears each have two identical wheels with tubeless tires. Each wheel contains a fusible plug which releases air from the tire in the event of excessive wheel heat.

Each pair of wheels is mounted on a staggered stub axle so that the outer wheel is slightly forward of the inner wheel. During retraction, the gear twists to bring the inner wheel directly over the outer wheel. This action permits the wheels to be stowed in a wheel well of the smallest possible size.

NOSE WHEELS

The nose landing gear has two identical wheels with tubeless tires rotating on a common axle.

WHEEL BRAKES

Normal System Operation

Main hydraulic system power is used to operate calliper-type disc brakes via Maxaret anti-skid units.

Master cylinders, operated by toe brake pedals through spring-struts, provide straight line and differential braking during normal and emergency operation. With the WHEEL BRAKE lever fully forward, main hydraulic system pressure, backed by the main accumulator, passes to a brake control valve via a main reducing valve. The control valve, in response to movement of the master cylinders, directs the related pressure through modulator units and Maxaret units to each brake unit.

Wheel Brake Lever (Figure 7)

Selection of braking for normal, emergency and parking use is controlled by a WHEEL BRAKE lever moving over a notched rack between a NORMAL mark (fully forward) and a rearward PARK BRAKE section.

An EMERGY position (first rearward notch) is marked in red. The WHEEL BRAKE lever is held in the emergency position and in progressive parking positions by a pawl engaging into the notched rack. A push button on the WHEEL BRAKE lever releases the pawl to permit movement of the lever from the EMERGY or PARK BRAKE positions. The lever can be moved rearwards from NORMAL to EMERGY without releasing the pawl.

Item Location

WHEEL BRAKE lever (Figure 7) Right side of center control pedestal

BRAKES (2) and SUPPLY combined hydraulic pressure indicator (Figure 8)

Center instrument panel below the MWS panel

WHEEL BRAKE EMERG annunciators L and R(Figure 8)

Right of combined hydraulic pres-sure indicator




Further rearward movement of the WHEEL BRAKE lever into the PARK BRAKE range progressively applies the brakes and at 1000 psi, the white WHEEL BRAKE EMERG annunciators illuminate. Full parking pressure is applied when the WHEEL BRAKE lever is in the PARK BRAKE position.

Pressure, supplied by the emergency brake accumulator, is maintained at the brake units by a lever mechanism which operates the brake control valve. A spring strut, initially loaded by the rearward movement of the WHEEL BRAKE lever, operates to reset the control valve when the WHEEL BRAKE lever is released to the NORMAL or EMERGY position.

Figure 7Wheel Brake Lever




A combined hydraulic pressure indicator shows the BRAKE pressures (upper indication) applied to the left and right brake units during normal operation.

The BRAKE indications are electrically operated from pressure transmitters connected into the normal supply lines to the brake units. The indicator also provides the main hydraulic system SUPPLY pressure (lower indication).

Emergency System Operation with Main System Pressure Exhausted

Movement of the WHEEL BRAKE lever rearward into the EMERGY notch effects the change from normal to emergency operation. An emergency reducing valve opens to allow emergency brakes accumulator pressure to enter the brake control valve. Brake pedal movement now results in pressure being applied directly to the brake units. Shuttle valves operate to isolate the normal supply so that the modulator units and Maxaret units are inoperative.

With the emergency system selected, the BRAKE indications continue to show normal system pressure to the brakes (provided there is still pressure in this system) but do not show emergency system braking pressure. WHEEL BRAKE EMERG annunciators with the legends L and R are provided to the right of the combined indicator and provide an indication of applied pressure to each brake unit.

Each annunciator is controlled by a pressure switch connected into the emergency supply line to the related brake unit. During brake pedal operation, the white annunciators are illuminated when the applied pressure reaches 1000 psi and remain on until the pressure is released to below this value.

The WHEEL BRAKE EMERG annunciators also act as a reminder that the anti-skid facility is isolated and that braking is direct.

OFF

221 1

00

BRAKE

23 1

4 OFF

SUPPLY 0

PSI x 1000

L REMERGWHEELBRAKE

Figure 8

Combined Hydraulic Pressure Indicator and Emergency Wheel Brake Annunciators

Left Gear Brake Supply Pressure

Right Gear Brake Supply Pressure

Main Hydraulic System Supply Pressure




POWER SUPPLIES

DC power distribution is as follows:

PE Busbar

WHEEL BRAKE EMERG annunciators

PS1 Busbar

BRAKES applied pressure indicators

NOSEWHEEL STEERING (Figure 9)

CAUTION: A STEERING DISCONNECT PIN MUST BE REMOVED BEFORE TOWING THE AIRPLANE. (Refer to Section 6, Sub-section 1 - GROUND HANDLING)

OPERATION

Hydraulic pressure is provided from the main hydraulic system for operation of the nose wheel steering.

CAUTION: NOSE WHEEL STEERING IS NOT AVAILABLE WHEN THE MAIN HYDRAULIC PRESSURE IS LESS THAN 2300 PSI. THE AUXILIARY HYDRAULIC SYSTEM CANNOT POWER THE STEERING SYSTEM.

When the nose gear is locked down, nose wheel steering is available through a range of 45° left and right of the center line. Steering is controlled from a handwheel located on the left-side console.

Rotation of the handwheel operates the selector valve input via cables and linkage. Movement of the selector valve directs hydraulic pressure to either extend or retract the steering actuator. The nose gear is turned in the required direction by the steering actuator.

When the required degree of turn has been reached, feedback through linkage connected to the landing gear moves the selector valve input to a neutral position. The nose gear stops turning and the selected angle is maintained. A steering on/off valve is operated by the nose gear mechanical indication linkage. The on/off valve is only selected on when the nose gear is locked down. After lift-off the nose gear is centered by the action of cams in the oleo strut.

WARNING: THE STEERING HANDWHEEL MUST BE FREE FROM OBSTRUCTION DURINGGEAR LOWERING. FAILURE TO MAKE SURE THE HANDWHEEL IS FREE TOMOVE MAY RESULT IN THE AIRPLANE VEERING OFF THE RUNWAYIMMEDIATELY ON TOUCHDOWN.

The reason the handwheel must be free from obstruction during gear lowering is that the geometry of the linkage from the handwheel to the selector valve causes the handwheel to rotate while the gear is lowering or retracting. The handwheel must be free to turn and to find its neutral position again prior to the gear locking down.

When the steering on/off valve is selected off, the steering actuator is isolated from the main hydraulic pressure for the purpose of preventing the gear being turned and striking the wheel bay.




Figure 9Nose Gear Steering System




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section - iii systems description - smartcockpithawker 800xp pro line 21 section iii - systems...

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