Hydraulics Flashcards
Which systems use hydraulic power?
Flt controls leading edge flaps/slats trailing edge flaps landing gear wheel brakes nose wheel steering thrust reversers autopilots
T/F: Airplane controllability is reduced with a single loss of sys A or sys B.
false. no reduction.
Where are the 3 hydraulic reservoirs?
in main wheel well.
Sys A and B incorporate a ______ that may prevent a total loss of system fluid should a leak develop.
standpipe
Which system services the standby system for pressurization?
Sys B supplies.
With pumps operating, what is normal hydraulic pressure?
3000 psi to a max of 3500 psi.
What does RF mean?
Hydraulic qty is below 76%. Only accurate with aircraft on ground and engines shut down or taxi-in with flaps up.
Sys A components:
Ailerons Rudder Elevator & elevator feel flight spoilers (2 on each wing) Ground spoilers Alt brakes No 1 Thrust reverser Autopilot A Normal nose wheel steering Landing gear Power Transfer Unit (PTU)
Sys B Components
Ailerons Rudder Elevator & Elevator Feel Flight Spoilers (2 on each wing) Leading edge flaps and slats Normal brakes No 2 thrust reverser Autopilot B Alternate nose wheel steering Landing gear transfer unit Autoslats Yaw damper Trailing Edge flaps
What types of pumps do Sys A and B have?
engine driven and electric. Engine driven pumps produce a flow rate 4x better than electric pumps.
Which generators supply power to the electric driven pumps?
Gen 1 supplies #2 elec pump
Gen 2 supplies #1 elec pump
How do the ENG hyraulic pumps work if their switches are moved off?
A blocking valve closes so fluid is isolated and the pump actually still works. Pump still rotates if engine is still on.
T/F: A minimum amount of fuel is req’d in each main tank for operation of the electric motor driven pumps
True.
What do hydraulic LOW PRESSURE lights mean?
Low output pressure from either engine-driven or electric hydraulic pumps.
What is the purpose of the PTU?
automatically supply an additional volume of hydraulic fluid to the autoslats and leading edge flaps and slats.
When will the PTU work?
only operate when Sys B engine driven pump volume is lost.
How does the PTU work?
uses Sys A pressure to power a hydraulic motor-driven pump which then pressurizes sys B
What are the conditions for the PTU to operate?
Must be airborne
Sys B engine driven pump pressure is low
Flaps are less than 15 but not up
What is the purpose of the Landing Gear Transfer Unit
uses Sys B engine driven pump pressure to raise the gear at the normal rate when Sys A engine driven pressure is low.
Conditions for Landing Gear Transfer Unit to work
Airborne
No. 1 eng at low RPM
Land gear lever is in UP position
either main gear is not up and locked.
T/F: the stby hydraulic system operates both manually and automatically
true
What systems are powered when the stby hydraulic system is activated?
thrust reversers, rudder, leading edge flaps and slats (for extension only); standby yaw damper
What does the electric hydraulic pump OVERHEAT light mean?
pump has overheated OR that hydraulic fluid that normally cools and lubricates pump has overheated.
Before initially applying power to the aircraft, ensure the ________ switches are off.
ELEC HYD PUMP
T/F: The ENG HYD PUMP switches are normally left ON to prolong solenoid life
True
If pushback is req’d w/out the use of a nose gear steering lockout pin, both Sys A pumps must be selected _____.
OFF
If the elec pump for Sys A is the only one on in flight, you may get an intermittent LOW PRESSURE light for the electric pump during __________.
heavy system demand.
What might be happening if LOW PRESSURE light flickers at high altitudes?
Foaming of the hydraulic fluid if the system is not properly pressurized.
The standby system is controlled manually through ________ or the _______
FLT CONTROL switches or ALTERNATE FLAPS master switch.
What happens when either FLT CONTROL switch is moved to the STBY RUD position?
electric motor driven pump activates. the related flt controll shutoff valve closes removing system pressure from the ailerons, elevator and rudder, The stby rudder shutoff valve opens. STBY RUD ON light illuminates.
What happens when you move the ALTERNATE FLAPS switch to ARM?
closes the trailing edge flap bypass valve
arms the ALTERNATE FLAPS position switch
allows the stby system to power the leading edge devices and thrust reversers
T/F: during critical phases of flight, the sby system operates automatically to compenstate for loss of sys A or B.
True
When will automatic operation of the STBY system occur?
Loss of Sys A or B Flaps extended Airborne or wheel speed is 60kts or greater Sys A or B FLT CONTROL switch on Main PCU Force Fight Monitor (FFM) trips
When is the STANDBY HYD LOW PRESSURE light armed?
stby operation has been selected manually or when the automatic standby function is active
What happens with complete loss of SYS A pressure?
both LOW PRESSURE lights come on, Sys A FLT CONTROL LOW PRESSURE and FEEL DIFF PRESSS lights illuminate.
With Sys A inop, what do you loose?
The No 1 thrust reverser has standby pressure for deployment , and the landing gear must be extended manually. d
What are the big things with loss of sys b?
Alternate brakes are available, No 2 thrust reverser and leading edge flaps and slats have standby pressure available and the trailing edge flaps are operated electrically.
With a loss of sys _____, the checklist calls for a flaps 15 landing using the ________
B; alternate flap extension.
The loss of both sys A and B is called what?
manual reversion. Indications are all 4 pumps show LOW PRESSURE and both Sys A and B FLT CONTROL LOW PRESSURE lights illuminated
What happens with manual reversion?
Sys A & B FLT CONTROL switches are moved to STBY RUD, the YAW DAMPER is selected ON allowing stby hyd power to power the stby yaw damper, and both Sys A and B switches are selected off.
What is inoperative for manual reversion?
Autopilots A & B
ALL flight spoilers
Ground spoilers
Trailing edge flaps via normal hydraulics
Leading edge flaps and slats via normal hydraulics
Main landing gear via normal hydraulics
nose wheel steering
Normal and alternate brakes
Autobrake
Both Thrust reverservs via normal hyd pressure.
Trailing edge flaps are operated electrically
Inboard and outboard brakes have accumulator pressure only
Manual gear extension is req’d
What is the landing configuration for manual reversion?
Flaps 15 landing using alternate flap extension. Manual gear extension. Once lowered, it can’t be retracted.
