Hydraulics Flashcards
What does HYD SYS A power? (7)
- Rudder, ailerons, elevator & elevator feel.
- No. 1 reverser
- 1/2 Flight spoilers
- Ground spoilers
- Landing gear and nose wheel steering
- Alternate brakes
- AP A
What is the maximum hydraulic system pressure?
3500PSI
What hydraulic pressure may read if pumps are off?
100PSI. This is the reservoir ambient pressure.
What percentage will the A system drop too if there’s an EDP leak?
20%. This remains for EMDP. EMDP leak will empty in case of leak.
What light will indicate if overheat of hydraulic system?
OVERHEAT
What is the minimum amount of fuel to ensure cooling of hydraulic system? (For EMDP operation)
760kg in each Main Tank.
What happens to EDP SOV if loss of electrical power?
EDP SOV fails to the OPEN position.
What happens to EDP if fire handle pulled?
EDP off, and the LOW PRESSURE light is inhibited.
Where are the hydraulic reservoirs pressurised from?
Pneumatic manifold
What does HYD SYS B power? (10)
- Rudder, ailerons, elevators and elevator feel
- 1/2 flight spoilers
- LE FLAPS and SLATS
- TE FLAPS
- Normal brakes
- No. 2 thrust reverser
- AP B
- Alternate nose-wheel steering
- Landing gear transfer unit
- PTU
What will HYD SYS B drain too in case of leak in either pump?
Empty. Enough remains to supply PTU.
What does the PTU provide?
Backup pressure to Autoslat system and LE devices.
Automatically opens to provide SYS A pressure when necessary to operate PCU.
When does PTU operate?
When output of B SYS EDP below limits, when aircraft inflight and flaps extended.
When may you see hydraulic fluid levels vary? (4)
- system becomes pressurised after start
- gear in transit
- LE devices in motion
- Cold soaking occurs in long cruise (little effect)
When may hydraulic foaming occur?
When not pressurised correctly at higher altitudes.
Recognised by pressure fluctuations and blinking LOW PRESSURE lights.
What does STBY HYD SYS power? (4)
- STBY Yaw Damper
- STBY Rudder PCU
- Autoslats (LE Devices)
- Both reversers
Until what level in B system will the reservoir supply the standby reservoir?
72%
When will the STBY SYS indicate LOW QUANTITY?
1/2 FULL and electrical power available.
When will yaw damper disconnect?
With B FLT CONT STBY RYD or OFF position. Needs to be re selected.
What powers alternate flap extension of LE devices?
Standby hydraulic system.
When will standby system automatically operate in case of A or B failure?
During TO or landing, for full rudder control during slow flight.
- Flaps extended
- Activation of FFM
- Wheel speed 60kts+
What is turning angle of the tiller?
78 degrees
What is the turning angle of the rudder?
6 degrees
How many air/ground sensors on the gear? (PSEU)
6, 2 on each gear.
What can you press if gear lever is stuck in position?
LOCK OVRD (A/G failure)
How many anti-skid valves per wheel?
4 per wheel. Relax pressure when skid develops.
What does the anti-skid do?
Receives information from wheel transducers and modulates hydraulic pressure to maintain maximum tyre friction.
How many valves does the alternate anti-skid system use through the anti-skid control unit?
2, 1 on each side.
What pressure is the brake accumulator charged too?
3000PSI
What pressure will the brake accumulator indicate when depleted?
1000PSI - precharge, not usable.
When is anti-skid INOP in normal operations?
When parking brake set.
What does ANTI-SKID INOP light mean?
Fault detected. Fault in parking-brake system may cause this.
What unit controls the autobrake?
Anti-Skid/Autobrake control unit (ASCU)
When only should RTO be selected? (5)
- On ground
- Wheel speed under 60kts
- Idle
- Antiskid and autobrake systems operational
- Autobrakes to RTO mode.
When will autobrakes activate on an RTO?
Above 90 knots when thrust levers to idle.
When does autobrake RTO automatically disarm?
Once airborne.
How are autobrakes disarmed? (4)
- Speedbrake down detent
- Advancing either thrust lever
- Applying manual brakes
- Autobrake switch to OFF
What provides roll input to Feel and Centering unit?
Cable from captains side. This then goes to aileron PCU’s.
Where are the balance tabs located?
Ailerons
What do you require for aileron trim to work?
Hydraulics or normal electrical power.
Can aileron trim activate spoilers?
Yes, if trim beyond 10 degrees.
What does the Spoiler Control Electronics Unit do?
Receives inputs from aileron PCUs. When control wheel raised over 10 degrees, extends to augment roll.
What does aileron transfer mechanism allow?
Use of one control wheel if the other is jammed.
When is aileron trim/spoiler mixing INOP?
Manual reversion if all hydraulics lost.
What are elevators and stabilizer powered by?
Elevators are hydraulic, stabiliser is electrical.
How are the elevators controlled?
Interconnected control columns provide dual cable input to 2 PCU’s. Each PCU has hydraulic pressure from separate system.
How many PTU’s or Hydraulic systems does elevator system need?
Can loose 1 PCU or 1 hydraulic system. Can’t loose 1 from each.
What does the elevator transfer mechanism allow?
Controls to move freely if one gets jammed.
What is the elevator jam landing assist system?
Uses spoilers for small changes to flight path when AP is OFF and F1 or greater. Need to select ON.
What hydraulic system does the Feel system use?
A or B, whichever has a higher pressure.
What 3 inputs does the elevator feel system receive?
- input from horizontal stabiliser position
- airspeed input from probes (vert. Stab)
- inputs from A and B hydraulic system.
When will FEEL DIFF PRESS Amber light illuminate?
Significant pressure differential sensed. As with Hydraulic failure.
MASTER CAUTION - FLT CONT
What enhances stall identification and control? (EFS)
- Yaw damper
- Elevator Feel Shift
- Speed trim system
When is Elevator Feel Shift (EFS) inhibited? (3)
- on ground
- RA under 100’
- AP engaged
What is the maximum speed with Mach trim failure?
280/0.82M
When will STAB OUT OF TRIM illuminate?
When AP engaged, and not trimming adequately. Out of trim when disengaged.
What does the control column trim cutout do?
If control force opposes trim direction, cuts out the trim. STAB TRIM switch to override.
MCAS - doesn’t do this with AFT control wheel motion.
Can a jammed elevator affect horizontal stabiliser motion?
Can cause loss of electrical trim. OVERRIDE switch will restore stabiliser trim.
When does speed trim occur?
Occurs during TO and GA with a low weight and aft CG.
Prevent stabiliser nose up trim exceeding elevator nose down capability.
What does speed trim do?
Prevent stabiliser nose up trim exceeding elevator nose down capability.
What trim circuit does speed trim use?
AP trim.
What are the conditions for speed trim operation? (5)
- between 100kts and M0.50
- 10 seconds after liftoff
- 5 seconds after trim switch release
- AP not engaged
- Sensed need of trim for stabiliser.
What does SPEED TRIM FAIL mean?
Fault with speed trim system.
When does rudder become effective on takeoff?
40-60knots
If STBY RUD ON selected, when will A or B hydraulic LOW PRESSURE light remain illuminated?
If STBY RUD SOV fails to open.
What is the standby yaw damper used for?
Improves handling qualities during manual reversion.
When is standby yaw damper available?
When both A+B switches to STBY RUD on, and YAW DAMPER is reselected to ON.
How much rudder deflection can the standby yaw damper command?
2.5 degrees driven by SMYD computer, when wheel input sensed.
What does the yaw damper prevent/do? (3)
- Dutch roll
- ensures turn coordination
- gust damping
How many SMYD computers?
2
What will happen to Yaw Dampet when hydraulic system B fails?
Yaw damper switch stays on until B system FLT CONT switch moved out of ON, to STBY RUD.
Above what speeds does both the A and B pressure at the main rudder PCU reduce by 25%?
135kts, to prevent rudder hardover.
What does the Force Flight Monitor do (FFM)?
Detects opposing A and B pressure at actuators. May occur if either system jammed/disconnected.
Automatically turns on STBY HYD pump pressuring standby PCU.
Indicated by STBY RUD ON.
What light will illuminate when FFM is on?
STBY RUD ON and MASTER CAUTION.
How many flight and ground spoilers?
4 and 2 on each wing. (8 and 4)
When will SPD EXT illuminate?
- When speed brakes extended beyond ARM position.
- Thrust lever above idle for 15 seconds
- TE flaps more than F10 (inflight)
- RA below 800’
When will SPD EXT illuminate on ground?
Ground spoilers not stowed, down detent.
What do the SPOILER SHUT-OFF switches control?
Only switches flight spoilers off.
What does Amber SPOILER light mean?
Spoiler fault.
When does Landing Attitude Modifier (LAM) function?
- when F30 or F40. Reduce lift for higher angle of attack.
- Between F15 and F30 and near idle, creates additional drag.
When will SPEEDBRAKE DO NOT ARM illuminate?
Malfunction exists. Can still use manually after landing. Light inhibited when in down detent.
When will auto spoiler extend during RTO?
Rejected above 60 knots.
When will Speedbrake extend on landing?
RA less than 6’ and gear compression.
In a rejected landing, when will spoilers and autobrake disengage?
Thrust levers past the mid point.
What monitors for skews and asymmetry in TE flaps?
Flap/Slat Electronic Unit (FSEU)
When will FSEU shutdown TE drive unit, and how is it indicated?
Uncommanded motion detected.
Only known when flap indicator disagrees with flap handle position. Cannot be reset, alternate system used.
What is TE flap load relief?
Operates at flap speed limit, and re-extends when 5kts below limit.
Operates for all flaps above F10.
Above what flap does load relief work?
F10
How many LE devices?
2 LE flaps and 4 slats on each wing.
What is the difference between LE flaps and slats?
- Flaps are hinged and rotate downwards
- Slats extend by moving forward to form slotted LE.
Where will LE FLAPS TRANSIT and LE FLAPS EXT illuminate?
On ENG display.
What are hydraulic system are LE devices powered by?
B. STBY is alternate.
When using alternate flaps, what pressure extends LE devices?
Standby pressure.
Does the FSEU monitor LE device asymmetry and skew?
Only asymmetry for all. No skew detection for slats 1 and 8, and LE flaps.
How does FSEU ensure LE devices stay retracted during cruise?
Maintains pressure on return lines.
Between what flap settings will autoslat move LE slats to full extend with high AOA?
F1-F25. Slats already fully extended at F30 and above.
Autoslats return to extend when AOA reduced.
What happens if inflight and B EDP pressure is low with regards to the Autoslats?
Hydraulic A system will power PTU to operate Autoslats with fluid from B reservoir.
Backup pressure in slow flight.
What is STBY HYD system pressurised by?
A single EMDP, from AC XFR BUS2
Maximum speed with gear down?
320 knots
Between what flaps does the PTU operate autoslats?
F1-25
How many times more powerful is EDP than EMDP?
6x
What is the only way to turn off EDP?
Pull fire handle
What are the 76’s to remember for hydraulics?
76% for RF. 760kg minimum for EMDP cooling.
What does FFM do?
Automatically brings STBY RUD ON if senses pressure from A or B is wrong.
When is FFM active?
Airborne, 60 knots+, loss of system A or B and flaps extended.
How many A/G sensors on wheels?
6, 2 on each
How long after UP does PSEU remove hydraulic pressure?
10 seconds
When is LANDING GEAR red?
Unsafe, in transit and below 800’ RA TL Idle and gear not down.
What is the maximum Mach for gear extension and extended?
M0.82
When is anti-skid disarmed with gear retracted?
Once retracted
What happens to anti-skid on alternate brakes?
Anti-skid in wheel pairs, not individual (like normal braking and accumulator braking)
What does antiskid protect against? (4)
- hydroplane
- skid
- locked wheel
- touchdown protection
Which pitot does elevator feel system use? What other inputs?
Pitot from tail, stabiliser position and A+B pressure.
What will illuminate if tail pitot blocked, or EFS senses hydraulics are wrong?
FEEL DIFF PRESSURE
How do you fix an elevator jam?
Breakout function, 62lbs of force.
What hydraulic pressure does elevator PCU use?
Either, whichever is higher pressure
When does speed trim work?
10 seconds after TO, 5 secs after trim release, AP OFF and sense trim requirement
How is speed trim disabled?
AOA disagree or PRI/BU switch
When does MCAS work?
Flaps up, airborne, 10 seconds after takeoff. Provides pitch stability.
What does speed trim fail mean?
Inhibited for rest of flight, exceeded trim limit. MCAS
When does the Cross FCC Trim monitor activate?
F15 or less
AP engaged
Not in GS/GP
Protects from erroneous trim runaway.
When can STAB OUT OF TRIM illuminate?
AP engaged or less than 30 knots.
What does the FO column control of aileron breakout?
Flight spoilers
When will SPD EXT illuminate?
TL greater than idle for 15 seconds
TL greater than 40 degrees for 3 seconds
Flaps over 10
Less than 800’ RA
When does LAM work?
F30/40. Also F15-25 when TL near idle.
When will extend ground spoilers?
Both MLG conpressed, wheel spin up and TL idle
When will auto speed brakes extend?
RA 6’
When will flight spoilers extend?
Any gear compressed
