1. Lever for landing gear in airbus are only 2 which are up and down
2.
landing gear down lock and secured
3. Lgciu cycles after it is used from 1 to 2, then to 1, and so on. It cycles everytime after full cycle of
system
4. Baulk solenoid serves as a locking lever which are actuated thru the data sensed by the proximity
switches (prox sw>lgciu>baulk solenoid
5. Lever D >lgciu>door selector valve> door down> lgciu>gear selector valve> gears>lgciu>door
selector valve>door close
6. Safety valve only use in flight at high speed faster than 260 knots
7. Landing gear gravity extension handle - turn clockwise
A. 3 turn cut out valve closed - depressurised green hydraulics
A. Cut oout valve close-no pressure- 1st
B. No resistance in return line/back to return line, vent valve- 2nd
C. Mechanical mechanism uplock actuator of doors and gears open causing freefall
of ldg
B. Doors unlocked/open
C. Gears unlocked
1. There are 3 types of braking
A. Normal
B. Alt
C. Inflight
2. Green is always prio
3. A/Skid&n/w strg if on powers up bscu
4. Bscu are autobreak and antiskid(tachometer/adiru-body moving,wheels not)
5. Autobrake: low - long runway-1.75ms2 deceleration, med-3ms2-2sec delay,max-6m/s2-rejected
takeoff
6. If A/Skid&n/w strg is off, yellow system is on, nl is depressurized
7. Nbptu send signals to bscu which open normal break selector valve and normal sservo valve
8. Nbptu alsso controls bscu it closes valve to turn on bscu(autobreak and antiskid actuates
9. Same output yellow/alternate - it is on auto
10. Abptu> abcu>bscu>abcu>alt braking selector valve and alt ddv
11. Parking break is emer break last resort opens parking brake control valve>shuttle valve>1,2,3,4
Hydraulic block purpose - it limits the capabilities of hydraulics for max steering angle
NOSE WHEEL STEERING
The steering system uses the yellow hydraulic system to operate a
steering actuating cylinder, which changes the direction of the NLG
wheels.
The steering system receives hydraulic pressure in the following
conditions:
- A/SKID & N/W STeeRinG switch is in ON position,
- towing control lever is in normal position,
- at least one ENG MASTER switch is ON,
- aircraft is on ground.
The steering system is controlled by the BSCU, which receives order
from:
- the steering hand wheels (orders added algebraically),
- the rudder pedals,
- the autopilot.
When the rudder pedal disconnect pushbutton is pressed in, N/WS is
disconnected from the pedals.
The BSCU transforms the orders into N/WS angle. That angle has the
following limits:
- Ruder pedals: max 6 degrees,
- Hand wheels: max 74 degrees.
The NLG is equipped with Rotary Variable Differential Transducers
(RVDTs), which are used as feedback sensors to the BSCU.
MLDG Extension
1. Lg lever down
2. Door uplock actuator open
3. Door mlg act
4. Door fully open(sensor)
5. Indicated in ecam
6. Mlg uplock act
7. Gear act retracted
8. Lock stay
9. Side stay
10. Down lock act
11. Door act closed
12. Door uplock act (mech closed)
MLDG Retraction
1. Lg lever up
2. Door uplock act open
3. Door mlg act open
4. Down lock mlg act open
5. Gear act extended
6. Uplock act mech closed(spring operated)
7. Door act closed
8. Door uplock mech closed
9. Door fully closed
Note: Mech-spring loaded
which will be pushed
- OVERCENTER-STRAIGHTEN
NLG EXT
1. LG LEVER DOWN
2. DR UPLOCK ACT OPEN
3. DR ACT OPEN
4. DR ACT SENSOR( FL OPEN)
5. NLG UPLOCK ACT
6. NLG GEAR ACT (EXTENDED
7. LOCK STAY DOWNLOCK ACT OVERCENTER(STRAIGHTEN)
8. DRAG STRUT ASS(OVERCENTER)
9. NLG DOWNLOCK ACT
10. DOOR ACT
11. DOOR UPLOCK MECH CLOSED
12. DR FLLY CLOSED (SENSED)
NLG RETRACTION
1. LG LEVER UP
2. DR UPLOCK ACT OPEN
3. DOOR ACT OPEN
4. DR ACT SENSOR
5. DOWN LOCK ACT GEAR OPEN
6. GEAR RETRACTED
7. LOCK STAY DOWNLOCK ACT (FOLDS)
8. DRUG STRUT (FOLDS)
9. UPLOCK ACT CLOSED ( MECH)
10. Dr downlock act open
11. Dr act
12. Dr uplock closed mech
13. Dr fully closed
Note: Mech-spring loaded
which will be pushed
- OVERCENTERSTRAIGHTEN
HANDLE ASSEMBLY
FREEFALL CTRL - HAS
BOTH CONNECTOR
AS MECH AND ELEC.
ELEC IS FOR THE
VALVES
1 OR 1.5 TURN OF HANDLE - CLOSED CUT OUT VALVE, NO PRES IN HYDRAULICS
VENT VALVE - VENTED PRESSURE TO AVOID CAVITATION AND RETURNS THE HYDRAULICS TO THE
RESERVOIR
1.6 - dr uplock released
1.9 TURN- 3 TURN - FREEFALL -DOOR AND GEAR UPLOCK OPEN(MECH), LDG FALLS TO DOOR THEN
GRAVITY DOES IT JOB LETTING BOTH FALL AND LOCKED BY DOWNLOCK BECAUSE OF INWARD
TENSION OF THE SPRING CREEATED BY THE SUDDEN MOMENTUM
1. NORMAL BRAKE - GREEN HYDRAULICS (NORMAL BRAKING
- HAS TRANSDUCER TO BSCU
- HAS SELECTOR VALVE (SELECTING WHETHER IT IS PRESSURE OR GOES TO RETURN LINE
- HAS FILTER
- GOES THRU THROTTLE VALVE WHICH SLOWS DOWN THE VELOCITY OF THE HYDRAULICS
TO INCREASE PRESSURE
- UP TO THE SERVO VALVE
- HAS A HYDRAULIC FUSE WHICH CUTS OUT WHEN THERE IS LEAKAGE IN HYDRAULICS FOR SAFETY
- AUTOMATIC SELECTOR WHICH SWITCHES TO YELLOW HYDRAULICS IF GREEN HYDRAULICS IS GONE/
NO PRESSURE
2. ALTERNATE BRAKING W/O ANTI SKID
- ALT BREAK
- MECH CREEATES PRES FROM HYD RESERVOIR THAT PUSHES MASTER CYLINDER DOWN
- YELLOW FROM ACCUMULATOR GOES THRU AUTO SEL UP TO THE DUAL VALVE
- PRESSURE OPEN THE DUAL SHUTTLE VALVE
- PRESSURE CONTINUES TO ALTN SV