A350 Landing Gear Flashcards
Which system controls the landing gears?
Landing Gear Extension and Retraction System (LGERS)
In which direction does the nose ldg gear retract?
Forward
Which doors on the nose ldg gear are open and which are closed when the ldg gear is extended?
- Front are closed (hydraulically actuated)
- Rear are open (mechanically linked)
What is the purpose of the bogie pitch trimmer?
- To keep the bogie in the correct position for ldg gear retraction
- To dampen bogie movement
Which hydraulic system operates the bogie pitch trimmer on the -900 and on the -1000?
- Green (always pressurised even if ldg gear retracted) (-900)
- Own hydraulic system (-1000)
Which hydraulic system operates the nose ldg gear?
And the main ldg gear?
- Yellow (with alternate power pack as backup)
- Green (with alternate power pack as backup)
When are the hydraulic lines to the landing gears pressurised?
- only during ldg gear extension and retraction
- isolation valve shuts it down once extended/retracted
How is the alternate power pack powered?
- Electrically by two elec pumps
- Convert elec power to hydraulic power
- Elec pumps are powered by two elec supplies
When does the ldg gear ctrl system switch?
- When the active one fails
- When ldg gear lever is selected up.
Roughly how long does it take to extend/retract the nose ldg gear?
20sec
Is hydraulic power used during gear gravity extension?
- Yes, by the alternate power packs
- To open the doors, (stay open)
What is the maximum time for gravity extension sequence?
90sec
Can the ldg gear gravity switch be reset in flight?
No, only on ground by maintenance
What are the braking modes?
- Normal Braking
- Alternate Braking
- Emergency Braking
- Park Brake
Which wheels are supplied by which hydraulic system in the A350-900/-1000?
A350-900:
- Front two (1,2,3,4)YELLOW
- Rear two (5,6,7,8) GREEN
A350-1000:
- Front (1,2,3,4,6,8) YELLOW
- Rear (5,7,9,10,11,12) GREEN
Where does hydraulic power come from during alternate braking?
Accumulators
How are the accumulators re-inflated?
- ACCU REINFLATE pb
- Automatically when engines are running
How many brake applications are available in emergency braking?
6 full brake applications (then still enough for park brake)
Summarize the braking modes, power supply, wheel control, and available functions?
NORM:
- Y,G hydraulics
- A/BRK and A/SKID available
- Wheels controlled indicidually
ALTN:
- Accumulators
- A/BRK and A/SKID available
- Lost below 1600psi (1800psi)
- Wheels controlled in pairs
EMER:
- Accumulators
- No A/BRK and A/SKID
- Only brake pedals
- Brake pressure limited to 1130psi (1250psi)
- Only 6 applications
- Wheels controlled in pairs
PARK BRK:
- Accumulators
- Max accu pressure
- Risk of tyre burst
- Wheels controlled in wheel groupsy
What is the target speed of the A/BRK system?
10kts, approx 60m before selected exit
How is the A/BRK disarmed/deactivated?
- Pressing brake pedals
- Pushing instinctive pb
- Pressing A/BRK pb
- Setting park brake
- Ground spoilers retract
- A/BRK arming conditions lost
At what speed does the RTO mode activate?
Above 40kts ground speed
What are some advantages of A/SKID?
- Reduced ldg distance, accel stop dist.
- Reduced tyre wear
- Prevents tyre burst
- Aquaplaning protection
When would you operate the A/SKID disconnection switch?
Only in the event of a “ LOSS OF BRAKING” procedure.
On the A350, does the NWS deactivate when the A-SKID sw is selected to OFF?
No, it’s a separate system and remains active
Why might there be a difference in accumulator pressure indications on the instrument?
G and Y accumulators are in two different locations and might be affected by different temperatures, therefore affecting the indication on the gauge.
If the accumulator pressure indicator shows that the pressure is in the white arc, what does this mean?
- Sufficient pressure to set park brake and start engines
- Insufficient pressure for engine tests
What braking mode is available when the accumulator pressure indicator shows a pressure between the 1.4 and 1.6 mark?
- Alternate or Emergency braking mode available
- No A-SKID
Which hydraulic system operates the NWS?
Yellow
What is the HCF?
- Heading control function
- Max of 3 degrees of NWS input to maintain aircraft on centerline of taxiway when steering tiller released
- Below 50kts
- Inhibited on takeoff
If the captain applies rudder and the FO also applies rudder, will the command be doubled?
No as the rudder pedals are connected mechanically
If the captain applies steering tiller input and the FO also applies steering tiller input, will the command be doubled?
It is algebraically added
What is the maximum NWS angle using the rudder pedals?
6 degrees decreasing with speeds above 100kts
What is maximum angle of NWS using the steering tiller? And on the -1000?
72 degrees decreasing with speeds above 30kts (75 degrees)
When the tiller disconnect pb is pressed what is disconnected?
- NWS from rudder pedals
- HCF
Which hydraulic system does the backup steering function use?
Green
How does the backup steering function operate?
It converts steering inputs from rudder pedals and tiller to differential braking commands on the main ldg gear.
When does the backup steering function not activate?
- During taxi out
- After an RTO
- One engine inop
- One or more green brakes not available in normal mode
- Nose wheel not free to swivel
