Hydraulics Flashcards
What happens if centre hydraulic system quantity is sensed low?
The centre No.1 elec pump is automatically isolated to provide hydraulic pressure to the RESERVE BRAKES & STEERING.The ISLN light for C HYD SYS on the rear panel illuminates.
What systems power the Flight controls?
All 3.
What does the RAT do?
Provides hydraulic pressure to the flight controls portion of the Centre Hydraulic System.Provides adequate hydraulic power for flight controls at speeds above 130kt.Deploys automatically when both engines fail. (Engines drop BLW idle)Cannot be stowed in flight.In right wheel well
What does the Pitch enhancement system do and when does it activate?
Auto activates if the Left & Centre HYD systems fail and trim switches are used.A pump in the right system (PTU) uses trapped left system fluid to operate the stabilizer.Elec trim is available at approx 1/4th of the rate. (Alternate and auto trim inop)
What systems have reservoirs? Are they pressurised?
Each system has own reservoir.PRESSURIZED from bleed air.
How is the centre hydraulic system demand pump powered?
By the Pneumatic system.
Does the centre Air Demand pump ever Auto operate?
Yes when there is a large demand on the centre system such as when operating the landing gear, flaps/slats and ground spoilers. Pump also operates whenever system pressure is low.(Air supply valve opens and pump operates to provide additional system pressure)
What Hydraulic pump is load shed and when?
The C2 pump.Load shed when on GND and only one source of electrical power. APU, EXT PWR or 1 ENG GEN.
Is an autopilot become inop when the left hydraulic system fails?
Yes the Left autopilot.
When will an RF appear on the hydraulic system quantity?
Below 0.75
When does the QTY light illuminate on the overhead panel and what other indication do you get with this?
Below .48 also illuminates HYD QUANTITY EICAS advisory message.
When does the RAT deploy automatically?
When both engines fail in flight.Provides adequate power for operation of the flight controls portion of the centre hydraulic system at airspeeds ABV 130kts.
When does the tail skid extend and retract and what powers it?
Extends and retracts with LDG gear, powered by the Centre HYD system.
Using Alternate Gear extension does the tailskid extend?
No
When do the gear doors stay open?
If there is no pressure in the centre hydraulic system after an Alternate gear extension.GEAR DOORS displays on EICAS
Is anti skid available in the alternate brake system?
Yes provided in normal and alternate systems.NORMAL- Each making gear wheel is provided with individual anti skid protection.ALTERNATE- Provided to laterally paired wheels.
How are the nose and main gear held in the up and locked position?
Nose gear- up locksMain Gear- door structure
What does the green PRESS light on the RAT panel indicate?
RAT is deployed andRAT is producing hydraulic pressure
When does Auto braking application commence on touchdown?
Both thrust levers retarded to idleWheels have spun upNose attitude is less then 1 degree
What does touchdown protection provide?
Ensures rear wheel brakes do not have hydraulic pressure at touchdown.
How does the braking system provide hydro planning protection?
Compares IRS ground speed to wheel speed and decreases aft wheel brake pressure when ground speed is greater then wheel speed.
How does the braking system provide locked wheel protection?
Compares the speed of each fore and aft wheel pair, and releases hydraulic pressure from the slower wheel when the speed difference is greater than 25kts.
What powers the Elevators?
Right, Center & Left systemsCan still power if 2 systems lost
Does Autopilot trim at the same rate as electric or manual?
No it trim as at one half the rate as it has only one trim control module.
When are the Electric trim switches inhibited?
During auto-land or Go-around with multiple autopilots engaged.
What are the 2 types of unsched stab trim?
Stabilizer moves without a trim signalStabilizer movement is opposite the direction signalled
What do the STAB TRIM CUTOUT switches do when in NORM & CUTOUT?
NORM- keeps hydraulic supply shutoff open.CUTOUT- shuts off respective Center or left hydraulic system power to the related stab trim control module.
What powers the rudder? Can it still operate if two systems are lost?
Pedals control 3 hydraulic actuators that move the rudder. Each system powers one. Can still operate if two systems lost but displacement limited.
What does the Rudder ratio changer do?
Uses airspeed information to vary the amount of rudder displacement providing structural protection for the rudder.LOW SPEEDS= Full displacementHIGH SPEEDS= Limited displacementPowered by the LEFT hydraulic system.
What happens if there is a rudder ratio changer fault?
Left HYD system automatically rudder actuator automatically depressurises to provide structural protection for the rudder.RUDDER RATIO- EICAS message displays.
What does the failure of a one Yaw Damper do?
Reduces the total yaw damping authority by one half.
What does no white band indicate on the stab trim indicator?
Stab trim indicator malfunctions other than power failure.
How many ailerons are there?
2 each wing- inboard and outboard.
How many spoilers are there?
12, 6 each wing= 2 x inboard. 4 x outboard.
What system powers the ailerons how many to have aileron control?
All three power them.If one or two systems are lost you still have aileron control.
What do the ailerons do with flap extension?
The inboards droop in conjunction with trailing edge flap extension.
When if ever are spoilers inhibited from responding to control wheel commands?
At cruise speed, two spoilers on each wing are inhibited this prevents over controlling.
Are ailerons ever locked out?
Yes at high speeds, prevents operation of outboard ailerons to protect against over controlling.
How many spoilers are used withe the Speedbrake lever inflight?
All but 2 are used. (4&9) 3rd from the fuselage, the first outboard.Should not be used with flap greater then 5 to avoid buffeting.
When will the speedbrakes extend if in the armed position?
Thrust levers idleHYD pressure to gear tilt actuatorsSensors detect airplane on the ground.
When do the speedbrakes automatically retract?
When thrust levers are moved from idle on ground.
When does the SPEEDBRAKES EXT and caution appear?
Speedbrakes are extended when RADALT is 800ft or BLW ORLaps are in landing position
How are the flaps and slats powered in the Normal and Alternate operation?
NORMAL- Hydraulic poweredALTERNATE- Electric
How many slats are there?
10 outboard- 5 a wing2 inboard- 1 a wingCenter HYD system powers through 3 separate power drive units
What happens when flaps are moved to position 1?
Just the slats extend to takeoff position.
What happens with flaps 5,15 & 20?
Slats- remain in takeoff position.Flaps- extend to required position & inboard ailerons droop in conjunction with flap extension.
What happens at Flaps 25 & 30?
Slats- Extend to their landing position.Flaps- extend to selected position. Inboard ailerons droop.
When does the flap load relief system arm and what does it do?
Arms at flaps 25 or 30.Retracts flaps position to 20Prevents flap extension to position 25, 30.Automatically reselects flap after speed is ok.Slats remain in LDG config.
How does the ALTN FLAPS work and what has priority?
Driven by electric motor.Overrides flap lever control inputs.
How long does the ALTN system take to extend to Flaps 20?
3 minutes.
Do you still have Flap Load relief protection during ALTN flaps selector?
No flap load relief!
Does the ALTN slat switch provide asymmetry protection?
No SLAT assymetry protection provided,
What system powers the spoilers?
Long range cruise cuts costs lots- for Left wingLong range cruise cuts costs right- for right wing
When is the alternate brake system pressurized and from where?
When right side pressure is low the center system automatically supplies pressure to the alternate system.
What does the Center hydraulic system power in regards to the LDG gear?
Retraction, extension & steeringAlternate brake system.
What system is the Autobrakes provided with?
Only normal system not Alternate.
How many power sources does each hydraulic system have?
L/R- each have two sources. EDP and an AC motor pump which operates on demand.Center- 4 sources. 2x AC motor pumps. 1 ADP (Demand). 1x RAT
Rudder ratio changer powered by?
Left system only and has only one actuator.
Why do you depressurize the right HYD system last?
-C & R systems share a part of the brake lines.-If R system is turned off prior to C system the brake source is changed to the C system and fluid transfer from R to C system occurs, the prevent this depress the R first.
