Landing Gear¶
Landing Gear: 1 LANDING GEAR¶
Landing Gear: 1.1 GENERAL¶
Landing Gear: 1.1.1 General¶
The landing gear has a forward retracting nose gear and two retractable main gears mounted partially in the side pods and partially in the fuselage. They are hydraulically operated and electrically controlled. Gear doors enclose the landing gear bays. The main landing gear supports a three section door to restore fairing contour when L/G is up and locked. Each main gear assembly has an oleo pneumatic shock absorber and is equipped with two wheels. Each main wheel is fitted with brakes and antiskid. The two wheel nose gear assembly includes an oleo pneumatic shock absorber and a nose wheel steering system. In case of hydraulic or electrical power supply failure, the landing gear can be extended by gravity.
Landing Gear: 1.2 LANDING GEAR¶
Landing Gear: 1.2.1 DESCRIPTION¶
Landing Gear: 1.2.1.1 Main Landing Gear¶
ACTUATOR ROLLER PIN TOWING FITTING TRAILING ARM SIDE BRACE JACK PAD WHEEL AXLE DOOR ATTACHMENT SPRINGS SHOCK ABSORBER SIDE BRACE FREE FALL ASSISTER TRUNNION LEG UNLOCKING ACTUATOR FREE FALL ASSISTER (GAS ACTUATOR) UPLOCK BOX
Landing Gear: 1.2.1.2 Nose Landing Gear¶
UPLOCK BOX STEERING ACTUATOR ACTUATING CYLINDER STEERING SWIVEL VALVE STEERING FEED BACK SYSTEM TOWING LUG SHOCK ABSORBER INNER CYLINDER SHOCK ABSORBER OUTER CYLINDER STEERING FEED BACK SYSTEM
Landing Gear: 1.2.1.3 Main Landing Gear Doors¶
Up 1 2 3
Move 1 2 3
Down
1 2 3
Landing Gear: 1.2.1.4 Gear Position Detection and Indication Systems¶
The landing gear position detection and indication systems has two independent systems.
Primary system is managed by MFC module 1A. The associated gear position is displayed on the main instrument panel. Secondary system is managed by MFC module 2A. The associated gear position is displayed on the overhead panel. Each system uses its own detectors and indications: - Downlock and air/ground signals from proximity sensors - Uplock signal from mechanical limit switches. Each system commands gear extension and retraction, gear anti-retraction system and the warning associated to "LDG GEAR NOT DOWN". Note Gear must be considered down if one system indicates 3 green lights. Each system has its own WOW circuit: WOW 1 into MFC module 1B and WOW 2 into MFC module 2B. The WOW signals are used by the MFC to have the system using WOW informations switched to the appropriate air/ground configuration.
Landing Gear: 1.2.1.5 Gear Normal Operation¶
Landing gear extension and retraction is performed by a control lever on the center instrument panel. The MFC electrically controls the landing gear selector valve in the LH main landing gear fairing. This valve supplies hydraulic pressure (green system) to: - Gear extension hydraulic line and connects the retraction line to tank return for extension, or - Gear retraction hydraulic line and connects the extension line to tank return for retraction. Note 1) As soon as the lever is selected up position, brake is applied automatically to the main gear wheels. 2) As soon as the gear is locked at its selected position, hydraulic pressure is released. Uplocking is mechanically achieved. Unlocking is hydraulically achieved. Down locking is achieved via a dual alignments folding side brace. Locking springs are used as secondary alignment and ensure locking independently of hydraulic pressure availability. Unlocking is hydraulically achieved.
Each main gear includes a door mechanism attached to it. The door is therefore operated by the gear during retraction and extension. Four doors close the nose gear and restore the fuselage profile. The doors are actuated mechanically by the gear. The two forward doors are closed after gear extension. The two aft doors remain opened while the gear is in extended position. Landing gear can not be retracted as long as at least one gear shock absorber detects weight on wheels.
Landing Gear: 1.2.1.6 Gear Emergency Extension¶
In the event of normal system failure the landing gear can be extended mechanically. The system is controlled from the flight compartment via a push/pull handle that enables mechanical unlocking of the landing gear. The landing gear extends due to gravity and aerodynamic forces. Main landing gear extension is assisted by a gas actuator and integrated springs. Nose landing gear is assisted by a mechanical device.
Landing Gear: 1.2.2 CONTROLS¶
Landing Gear: 1.2.2.1 LDG Gear Control Panel¶
L_CB_00000000_0000000_000_00_00
UNLK UP DOWN UNLK 1 2 UNLK LDG GEAR 1 Landing Gear Control Lever The lever must be pulled out before selecting one of the two possible positions: UP The landing gear retraction is selected. DOWN The landing gear retraction is selected. A red light is inserted in the LDG GEAR lever. If any one of the gears is not sensed in the down and locked position the light comes on and the FWS will be activated through the MFC. 2 Landing Gear Position Indicator Displays the gear position as sensed by MFC 1. comes on green when respective downlock is engaged. UNLK comes on red if respective gear is not locked in accordance with the lever selected position or, if on ground, the uplock box is not in the open position.
Landing Gear: 1.2.2.2 LDG Gear Position Indicator Overhead Panel¶
LDG GEAR UNLK UNLK UNLK LDG GEAR UNLK light Displays the gear position as sensed by MFC 2. comes on green when respective downlock is engaged. UNLK comes on red if: - The corresponding gear is not locked when the lever is down, or - The uplock box is not in the open position on the ground.
Landing Gear: 1.2.2.3 LDG Gear Emergency Extension Handle¶
1
2 1 Open the panel. 2 Pull the handle until it is above the top of the pedestal to unlock the landing gear. CAUTION Do not twist handle when operating.
Landing Gear: 1.2.2.4 MFD Indication¶
MFD
ACW BUS 1 FAULT ACW GEN1 BTC ACW BUS 2 FAULT ACW GEN2 TRU DC EXT PWR AVAIL ON MAIN BAT AUX HYD BLUE HYD GREEN HYD STBY PSI 3000 PSI 3000 X FEED FLAPS SPOILERS NORM BRK LDG GEAR EMER BRK PROP BRK N/W STRG PSI 3000 ACCU
2 1 2 ITEM DISPLAY DESCRIPTION 1 NORM BRK LDG GEAR GREEN SYSTEM MESSAGES OVERVIEW 2 NORM BRK LDG GEAR NOMINAL PRESSURE CONDITION NORM BRK LDG GEAR LOSS OF GREEN SYSTEM PRESSURE (BELOW 1 500 psi)
Landing Gear: 1.2.3 ELECTRICAL SUPPLY¶
Landing Gear: 1.2.3.1 Electrical Supply¶
EQUIPMENT DC BUS SUPPLY (C/B) AC BUS SUPPLY (C/B) Primary detection system Landing gear CTL indication and alert DC STBY BUS (on lateral panel C/B LDG GEAR CTL) NIL Secondary detection System indication and Alert DC BUS 2 (on lateral panel C/B IND and WARNING) NIL Weight on wheels (air/ ground detection) System 1 DC EMER BUS (on lateral panel C/B WOW SYS 1) NIL System 2 DC BUS 2 (on lateral panel C/B WOW SYS 2) NIL
Landing Gear: 1.2.4 SYSTEM MONITORING¶
Landing Gear: 1.2.4.1 LDG GEAR UNSAFE INDICATION-Alert 1¶
CONDITION VISUAL AURAL Any gear not seen down locked, and FLAPS 30, and ZRA < 500 ft - MW light flashing red - LDG GEAR NOT DN red message on EWD - Red light on landing gear lever - Any green ∇ light turn OFF on either panel CRC which can not be silenced by pressing MW pb
Landing Gear: 1.2.4.2 LDG GEAR UNSAFE INDICATION-Alert 2¶
CONDITION VISUAL AURAL Any gear not seen down locked, and at least one PL at FI, and RA<500 ft - MW light flashing red - LDG GEAR NOT DN red message on EWD - Red light on landing gear lever - Any green ∇ light turn OFF on either panel CRC which can be silenced by pressing MW pb
Landing Gear: 1.2.5 LATERAL MAINTENANCE PANEL¶
Landing Gear: 1.2.5.1 WOW Selector¶
On the RH maintenance panel, a selector enables the weight on wheels systems to be selected to the in “FLIGHT” position when on the ground, for maintenance purposes.
WEIGHT ON WHEELS CAUTION BEFORE SEL FLT MODE CHECK: GUST LOCK: OFF CAB TEMP <30°C AIRCRAFT STOPPED EXHAUST MODE: NORM STICK PUSHER: OFF MODE FLT NORM 1
1 Mode Selector Controls the overriding of weight on wheels system. NORM The system works normally. FLT The systems are forced to the in “FLIGHT” position. MAINT PNL light comes on amber on the EWD.
Landing Gear: 1.2.5.2 Failures Readout Display¶
A maintenance failure indication of any WOW proximity switch is provided via a specific MCDU maintenance page.
BASIC MEMORY FLT FAULT MEMORY MAINT MEMORY ERASING COPY TO PCMCIA RETURN V V V V V V V MFC V V V V V * PRINT BASIC MEMORY NAV DOORS WOW & LG PRINT V V V V V V V V V V V V BOOTS BRK RETURN MISC3 MISC1 FLT CTL MISC2 MFC/MISC4 1 2
Landing Gear: 1.3 NOSEWHEEL STEERING¶
Landing Gear: 1.3.1 DESCRIPTION¶
Landing Gear: 1.3.1.1 Description¶
Nosewheel steering is provided via a servomechanism mechanically controlled from the flight compartment and powered by the blue hydraulic system. Control is achieved using the steering control hand wheel mounted on the captain's lateral console. Nose steering angle is ±60 °. Nosewheel deflection of ±91 ° is possible during towing with no pressure in the system. An internal mechanism brings the wheel back to centered position when the aircraft is off the ground. A swivel valve shuts off hydraulic pressure to the steering system if the nose landing gear is not locked down. Pressure is also shut off by a solenoid valve if the main and nose gear shock absorbers are not compressed. Note If any gear leaves the ground after all gears have been compressed, the steering control is maintained as long as one gear at least stays on the ground. A switch is provided to deactivate the steering system if required. In case of either steering system deactivation or blue hydraulic pressure failure, the aircraft can be guided using differential braking and/or differential engine thrust. Refer to Schematics
Landing Gear: 1.3.2 CONTROLS¶
Landing Gear: 1.3.2.1 NW STEERING Guarded Switch¶
N/W STEERING OFF
N/W STEERING Guarded Switch The N/W STEERING guarded switch controls activation/deactivation of the nosewheel steering system. The switch is guarded in ON position. ON The steering solenoid valve is electrically armed. The solenoid is energized when the steering relay is energized. The valve opens when the steering hydraulic control is actuated. OFF Unpressurizes the steering system by de-energizing the solenoid valve.
Landing Gear: 1.3.2.2 Steering Handwheel¶
The steering handwheel controls the nosewheel steering angle up to 60 ° in both directions: - Clockwise: Steering to the right - Counterclockwise: Steering to the left. Note Nosewheel steering is self centering after liftoff.
Landing Gear: 1.3.2.3 MFD Indication¶
MFD
3 4
ACW BUS 1 FAULT ACW GEN1 BTC ACW BUS 2 FAULT ACW GEN2 TRU DC EXT PWR AVAIL ON MAIN BAT AUX HYD BLUE HYD GREEN HYD STBY PSI 3000 PSI 3000 X FEED NORM BRK LOG GEAR EMER BRK PSI 3000 ACCU FLAPS SPOILERS PROP BRK N/W STRG ITEM DISPLAY DESCRIPTION 3 14, 0, 4, 3 V13.2 L_CB_00000000_0000000_000_00_00 FLAPS SPOILERS STRG N/W PROP BRK BLUE SYSTEM MESSAGES OVERVIEW 4 14, 0, 4, 3 V13.2 L_CB_00000000_0000000_000_00_00 FLAPS SPOILERS STRG N/W PROP BRK STEERING AVAILABLE FLAPS SPOILERS STRG N/W PROP BRK BLUE SYSTEM PRESSURE BELOW 1 500 psi OR N/W STEERING sw ON OFF POSITION
Landing Gear: 1.3.3 ELECTRICAL SUPPLY¶
Landing Gear: 1.3.3.1 Electrical Supply¶
EQUIPMENT DC BUS SUPPLY (C/B) AC BUS SUPPLY (C/B) Nosewheel steering selection valve DC EMER BUS (on lateral panel C/B STEERING VALVE) NIL
Landing Gear: 1.3.4 SCHEMATICS¶
Landing Gear: 1.3.4.1 Schematics¶
BLUE HYDRAULIC SUPPLY -> [SWIVEL VALVE] -> [SOLENOID VALVE]
|
N/W STEERING switch --> [MFC / relay control] ----+
v
STEERING HANDWHEEL ----------------------> [STEERING CONTROL UNIT]
|
v
[STEERING ACTUATOR] -> nose wheels
|
RETURN
Landing Gear: 1.4 BRAKE-ANTISKID¶
Landing Gear: 1.4.1 DESCRIPTION¶
Landing Gear: 1.4.1.1 Wheel and Brakes¶
The four main gear wheels are equipped with multidisc brakes, each operated by hydraulically powered pistons. Two modes are available: - Normal: The flight crew controls the brakes via the brake pedals (supplied by the green system) - Emergency and braking: The flight crew controls the brakes via the emergency and parking brake handle (supplied by the blue system). Each brake is equipped with an automatic adjuster, a wear indicator pin, and an overheat detector. The main gear wheels are braked automatically as soon as the flight crew sets the LDG GEAR lever UP. The main gear wheels are fitted with three fusible plugs (overheat protection) and one pressure relief valve (overpressure protection). These device protect against tire and wheel burst in the event of overpressure overheat at fuse location. These fusible plugs are designed to release internal pressure if the wheel temperature reaches a preset value. The wheels are fitted with tubeless tires.
Landing Gear: 1.4.1.2 Antiskid Block Diagram¶
FUNCTIONAL ABSTRACTION - antiskid control loop
WHEEL SPEED -> squarer / reference-generation channels -> velocity reference
| |
+---------------- actual wheel velocity --------------+
v
[COMPARATOR / ERROR]
|
skid detection / transient control
|
BRAKE PEDAL / metering-valve command ----------------------+--> current command
|
v
[ANTISKID VALVE]
|
BRAKE PRESSURE
Spin-up / touchdown logic and locked-wheel protection modify the control path.
Landing Gear: 1.4.1.3 Antiskid System¶
The antiskid system operates as soon as the gear is down and locked, and as long as the aircraft speed exceeds 10 kt. Each wheel and each pair of external or internal wheels are monitored. The aim of the system is to provide the maximum stopping performance by controlling brake pressure. This system minimizes wheel slip depending on brake power, tire wear, and runway condition. Touchdown protection is ensured (spin up, locked wheel). The system consists of: - four wheel speed transducers (one per main gear wheel) - One control box - One antiskid module. A reference velocity signal is computed. The antiskid applies a deceleration law and continuously adjusts the wheel speed to the reference speed. In the event of electrical supply loss, the antiskid is no more operative and brakes are directly operated.
Landing Gear: 1.4.1.4 Locked Wheel Protection¶
The system includes locked wheel protection to avoid tire burst. The system compares inboard main wheels speeds and also outboard mains wheels speeds. When aircraft speed is above 23 kt, if the differential speed (inboard or outboard) is at or above 50 % then the brakes are released.
Landing Gear: 1.4.1.5 Touchdown Protection¶
At main gear compression, the braking action is inhibited as long as wheel spin up is below 35 kt or for 5 s, in order to prevent inadvertent brake application on low friction pavements or with light wheel vertical loading. In the event of electrical supply loss, the antiskid is no longer operative and brakes are directly operated.
Landing Gear: 1.4.2 CONTROLS¶
Landing Gear: 1.4.2.1 Pilot Brake Pedals¶
Controls normal braking mode through the normal metering valve. Differential braking is possible with brake pedal individually operated.
Landing Gear: 1.4.2.2 Emergency-Parking Brake Handle¶
OFF BRK PARKING E M E R E M E R
Emergency-Parking Brake Handle Controls emergency and parking braking mode through the emergency and parking metering valve. Spring-loaded to the OFF position. EMER A metered pressure is applied to the brakes. PARKING Full pressure is applied to the brakes CAUTION Brake handle applies braking without antiskid operation. Note 1) In case of hydraulic power system failure, the brake accumulator enables at least 6 braking applications. 2) If brake handle is not in the fully released position, amber PRKG BRK caution light comes on on EWD and is taken into account by the T.O CONFIG warning system.
Landing Gear: 1.4.2.3 Antiskid Panel¶
14, 0, 4, 3 V13.2 L_CB_00000000_0000000_000_00_00
TEST ANTISKID OFF 1 2
1 ANTI SKID pb Controls activation/deactivation of the antiskid system. Pb pressed in Antiskid system is activated. OFF Antiskid system is deactivated. OFF light comes on white. 2 TEST pb Press the button initiates an automatic sequential test to check the primary antiskid protection capabilities of the system. The test duration is approximately 3 s in flight and 6 s on ground. If initiated on ground when brake pedals are pushed, the test duration is sufficient to enable observation of the brake compression and release. WHEELS A-SKID amber caution is displayed on EWD. CAUTION When engines are running on ground, the flight crew must ensure that the parking brake is set before performing this test. Note The test is inhibited if wheel speed exceeds 17 kt.
Landing Gear: 1.4.2.4 Parking Emergency Braking Accumulator Pressure Indicator¶
In addition to the PRKG BRK ON annunciation on EWD and the Parking / Emergency Braking Accumulator displayed on MFD ACW/HYD page, the aircraft is fitted with a Parking / Emergency Braking Accumulator pressure indicator on the left maintenance panel.
OFF ON ONLY WHEN NORM IND LOST BRAKE ACCU HYD PSI x 1000
Parking Emergency Braking Accumulator Pressure Indicator This indicator is used to read Brake Accumulator Hydraulic Pressure if batteries are OFF, for ground towing operations or in case of the main indication loss. If the switch is activated, the indicator is energized for 2 min. If the hydraulic pressure of the accumulator is below 1 700 psi or above 3 100 psi, the indicator displays blinks. Brake Accumulator Hydraulic pressure is displayed in green. The displayed value has to be multiplied by 1000 (as described by the legend on the front face).
Landing Gear: 1.4.2.5 MFD Indication¶
MFD
7 5 6 ACW BUS 1 FAULT ACW GEN1 BTC ACW BUS 2 FAULT ACW GEN2 TRU DC EXT PWR AVAIL ON MAIN BAT AUX HYD BLUE HYD GREEN HYD STBY PSI 3000 PSI 3000 X FEED FLAPS SPOILERS PROP BRK N/W STRG NORM BRK LOG GEAR EMER BRK PSI 3000 ACCU
ITEM DISPLAY DESCRIPTION 5 NORM BRK LDG GEAR GREEN HYDRAULIC SYSTEM MESSAGES OVERVIEW 6 NORM BRK LDG GEAR NOMINAL PRESSURE CONDITION NORM BRK LDG GEAR LOSS OF GREEN HYDRAULIC SYSTEM PRESSURE (BELOW 1 500 psi) 7 EMER BRK ACCU PSI 3000 NOMINAL PRESSURE CONDITION EMER BRK ACCU PSI 1400 EMERGENCY BRAKING NOT AVAILABLE PRESSURE BELOW 1 600 psi EMER BRK ACCU PSI
INVALID ACCUMULATOR PRESSURE
EWD 14, 0, 4, 3 V13.2 L_CB_00000000_0000000_000_00_00
LOOP FIRE 1 LOOP FIRE 2 TAT SAT 20000 2000 KG KG FOB GW 12 12°C °C 12 52 H 13 : 0 500 ITT °C 500 0 NP % S S TQ % 83.4 CRZ 100 90.2 82.0 663 663 82.0 0 50 83.4 CRZ 100 90.2 0 50 UP 5 0 DN UP 3.0 L R L I A R U D TYPICAL MESSAGES --° SEL P I T C H F L A P FUEL USED KG 0 0 FT H 0 00 1
TOPIC DISPLAY DESCRIPTION ANTI SKID TEST RESULT A-SKID TEST F F F F FAILURE ON ALL WHEELS OR TEST IN PROGRESS “WHEELS” CAUTION IS TRIGGERED A-SKID TEST N N N N NO FAILURE DETECTED A-SKID TEST N F N N SINGLE FAILURE DETECTED (LEFT INBOARD WHEEL- EX. SHOWN) BRAKING MESSAGES a b EMER BRK LOPR PRKG BRK ON a : ACCUMULATOR PRES < 1 600 psi b : PARKING BRAKE ENGAGED a b EMER BRK LOPR a : ACCUMULATOR PRES < 1 600 psi b : PARKING BRAKE RELEASED a b USE EMER BRK PRKG BRK ON a : GREEN HYDRAULIC SYSTEM PRES < 1 500 psi (AND ACCUMULATOR PRES >1 600 psi) b : PARKING BRAKE ENGAGED a b USE EMER BRK a : GREEN HYDRAULIC SYSTEM PRES < 1 500 psi (AND ACCUMULATOR PRES >1 600 psi) b : PARKING BRAKE RELEASED b PRKG BRK ON b : PARKING BRAKE ENGAGED WHILE ACCUMULATOR AND GREEN HYDRAULIC SYSTEM PRESSURES ARE > 1 600 psi AND 1 500 psi RESPECTIVELY AND TLU LO SPEED NOT SET
Landing Gear: 1.4.3 ELECTRICAL SUPPLY¶
Landing Gear: 1.4.3.1 Electrical Supply¶
EQUIPMENT DC BUS SUPPLY (C/B) AC BUS SUPPLY (C/B) Antiskid control for inboard wheels DC ESS BUS (on lateral panel C/B INBOARD WHEELS) NIL Antiskid control for outboard wheels DC EMER BUS (on lateral panel C/B OUTBOARD WHEELS) NIL Antiskid caution system DC STBY BUS (on lateral panel C/B CAUTION) NIL EMER brake ACCU pressure indication DC STBY BUS (on lateral panel C/B PRESS IND) NIL Brake TEMP system DC STBY BUS (on lateral panel C/B MONITORING SYS) NIL
Landing Gear: 1.4.4 SYSTEM MONITORING¶
Landing Gear: 1.4.4.1 ANTISKID FAULT-Alert¶
CONDITION VISUAL AURAL Antiskid channel loss (power loss or loss transducer or valve continuity) - MC light flashing amber - WHEELS A-SKID amber message on EWD - Associated F displayed amber on EWD SC
Landing Gear: 1.4.4.2 BRK TEMP HOT-Alert¶
CONDITION VISUAL AURAL Brake temperature over 150 °C - MC light flashing amber - WHEELS BRK HOT amber message on EWD SC
Landing Gear: 1.4.5 LATERAL MAINTENANCE PANEL¶
Landing Gear: 1.4.5.1 BRK Temp Test¶
On the RH maintenance panel, a test pushbutton is used to check brake overheat detection system. If pressed in, the FWS is activated.
PTT BRK TEMP 14, 0, 4, 3 V13.2 L_CB_00000000_0000000_000_00_00
Landing Gear: 1.4.6 SCHEMATICS¶
Landing Gear: 1.4.6.1 Schematics¶
BLUE GREEN M M M L R OFF BRK PARKING E M E R E M E R AUXILIARY PUMP BLUE PUMP X FEED GREEN PUMP PILOT PEDALS EMERGENCY BRAKE ACCUMULATOR ANTI SKID MODULE EMERGENCY AND PARKING MODE METERING VALVE NORMAL MODE METERING VALVE ANTI SKID VALVES SHUTTLE VALVES FUSES
BLUE SYSTEM --> blue/aux pumps --> emergency-brake accumulator
| |
+--> emergency/parking metering valve --> shuttle valves --> wheel brakes
GREEN SYSTEM --> green pump --> normal metering valve --> antiskid module
| |
PILOT PEDALS ---------------------------------------------+--> antiskid valves
+--> shuttle valves
+--> four wheel brakes
X-FEED connects blue and green supply paths when selected.
Landing Gear: 2 TAIL BUMPER¶
Landing Gear: 2.1 Tail Bumper¶
RED INDICATOR SKIN PANEL SKID SHOE
- Fig. 1 : Tail Bumper - At each walkaround, inspect skid shoe. In case of scratches, if red indicator:
- Does not show mark of wear, aircraft can be dispatched
- Shows mark of wear, maintenance action is required.