Question about Landing Gear System

 If there is any conflicting information, your FCOM shall be the overriding reference.

 Q1. What happens to the green hydraulic supply to L/G when a/c is flying faster than 260kts?
A1. When the aircraft is flying faster than 260 knots, a safety valve automatically cuts off hydraulic supply to the landing gear system

Q2. At what speed will the safety valve cut off hydraulic pressure to the landing gear?
A2. Above 260 knots.
Q3. Will landing gear operate normally if ADR 1 + 3 fail?

A3. In the case of ADR1+3 Fault, the Landing Gear Safety Valve is controlled closed.
–> Landing Gear retraction is inoperative
–> Landing Gear Extension must be performed by gravity.
Q4. What happens when the Emergency Gear Extension crank handle is operated?
A4. When a crew member turns the crank, it :-
–> Isolates the landing gear hydraulics from the green hydraulic system,
–> Unlocks the landing gear doors and the main and nose main gear,
–> Allows gravity to drop the gear into the extended position.
Q5. Is nose wheel steering available after emergency gear extension?
A5. No.

Q6. After emergency gear extension do the gear doors remain open?A6. Yes.
Q7. How many LGCIUs are fitted on A320 a/c and what is the transfer logic for each LGCIU?
A7. There are 2 LGCIU's fitted on the A320. One LGCIU controls one complete gear cycle, then switches over automatically to the other LGCIU at the completion of the retraction cycle. It also switches over in case of failure.
Q8. What is the function of LGCIU?
A8. Two Landing Gear Control and Interface Units (LGCIUs) control the extension and retraction of the gear and the operation of the doors. They also supply information about the landing gear to ECAM for display, and send signals indicating whether the aircraft is in flight or on the ground to other aircraft systems.
Q9. What is the meaning of red UNLK lights on the LDG Gear Indicator panel?A9. The RED UNLK Lights come on Red if the gear is not locked in the selected position.
Q10. Is it true that the lights on the LDG GEAR INDICATOR panel illuminate if the LGCIU #1 is supplied with electricity?
A10. Yes. The lights on the LDG GEAR indicator panel come on as long as the LGCIU#1 is electrically supplied.
Q11. What does the RED ARROW on the landing gear selector lever indicate?
A11. The RED ARROW lights up if the landing gear is not locked down when the aircraft is in the landing configuration, and a red warning appears on ECAM.
Q12. What are the indications if landing gear is not locked down when landing config is selected on the a/c?
A12. To indicate that the Landing Gear is not locked down when in landing config is selected, the following happen :-
–> Aural CRC warning
–> MASTER WARNING light
–> DOWN ARROW light on Landing Gear Panel
–> GPWS "TOO LOW GEAR" warning
Q13. What is the meaning of "LDG CTL" legend appearing on ECAM WHEEL page?A13. This legend appears in amber along when the landing gear lever and the landing gear position do not agree. This legend only appears when the landing gear is moving to the selected position.
Q14. What is the meaning of ECAM GEAR NOT DOWNLOCKED?
A14. The ECAM warning of GEAR NOT DOWNLOCKED indicates that one of the gear is not downlocked with the L/G selected down.
Q15. What is the meaning of ECAM GEAR NOT DOWN?
A15. The ECAM GEAR NOT DOWN comes on in the following conditions :-
–> L/G not downlocked and radio height lower than 750 ft and both engines N1 lower than 75 % (or if engine shut down N1 of remaining engine lower than 97 %) or
–> L/G not downlocked and radio height lower than 750 ft and both engines not at T.O. power and flaps at 1, 2, 3 or FULL or
–> L/G not downlocked and flaps at 3 or FULL and both radio altimeters failed
Q16. How an LGCIU failure is indicated on the ECAM WHEEL Page?
A16. The landing gear positions are indicated by 2 triangles for each gear on the ECAM WHEEL page. The left triangle is controlled by LGCIU 1, the right one by LGCIU 2. Left or right amber crosses in place of the triangles indicate respectively that LGCIU 1 or LGCIU 2 is failed.
Q17. What is the meaning of a red triangle, if shown on WHEEL Page?
A17. A red triangle indicates that one LGCIU detects a landing gear in transit.
Q18. How is the landing gear held in place when retracted?
A18. The Landing Gear is held in place when retracted by an MLG Uplock which is a mechanical device that automatically locks the main gear in the retracted position. The uplock is closed mechanically and opened hydraulically in the normal extension and retraction mode.
Q19. Is nose wheel steering available with the YELLOW hydraulic system inoperative?
A19. No.
Q20. Is it true that when using the rudder pedals for nose wheel steering, the steering angle starts to reduce at 40 knots and progressively reduces to zero degrees at 130 knots? Above 130 kts N/W Steering is not available from rudder pedals?
A20. True.
Q21. When the towing control lever is in the tow position, a green NW STRG DISC message is displayed on ECAM. What happens to the message after the first engine is started?
A21. The message appears in Amber after first engine start.
Q22. At what speed is the nose wheel steering angle reduced when using the steering hand wheels?A22. Upto 20 knots the Steering Hand wheels can steer the Nose wheel through +/- 75 degrees. The nose wheel steering angle progressively reduces from 20 knots to zero at 80 knots.
Q23. What message is displayed on ECAM when the towing control lever is in the tow position?A23. "NW STRG DISC" is displayed in Green.
Q24. Is there any visual means to check landing gear position?A24. No.
Q25. How many brake systems are installed on the aircraft?A25. Two Brake systems are installed on the aircraft. The normal system uses green hydraulic pressure, whereas the alternate system uses the yellow hydraulic system backed up by the hydraulic accumulator.
Q26. Which computer controls normal braking functions?A26. In normal operation, a dual channel Brake and Steering Control Unit (BSCU) controls normal braking and antiskid.
Q27. Which hydraulic system is used for Normal brake system?A27. The normal system uses green hydraulic pressure.
Q28. Which hydraulic system is used for Alternate brake system?A28. The alternate system uses the yellow hydraulic system backed up by the hydraulic accumulator.
Q29. Which of the brake functions are lost If braking capabilities degrade to alternate brakes with antiskid?A29. AutoBrake function is inoperative.
Q30. Does the alternate brake system have the same capabilities as normal brakes?A30. No.
Q31. Is it true that Normal brake system is still available and not inhibited when parking brakes are applied?A31. When you set the PARK BRK control switch to the ON position, this deactivates the other modes and supplies the brakes with Yellow high pressure.
Q32. With which of the failures, braking capabilities degrade to alternate brakes without anti-skid?A32. The following failures cause the braking capability to degrade to alternate brakes w/o antiskid :-
–> Electrically (A/SKID & N/W STRG s/w OFF, or power supply failure, or BSCU failure), or
–> Hydraulically (Y + G system low pressure, the brakes are supplied by the brake accumulator only).
Q33. On which of the hydraulic system does Auto-brakes work?A33. Green Hydraulic System.
Q34. After touchdown, with the auto brakes selected, what control surface must move before auto braking will begin?A34. Ground Spoilers.
Q35. What speed must be met or exceeded during rejected takeoff for Auto brakes to activate?A35. 72 Knots.
Q36. What does each of the indicators on the AUTO BRK pushbuttons indicate?A36. The following are the indications on the AutoBrake panel :-
–> LO : LO mode sends progressive pressure to the brakes 4 s after the ground spoilers deploy, in order to decelerate the aircraft at 1.7 m/s² (5.6 ft/s²).
–> MED : MED mode sends progressive pressure to the brakes 2 s after the ground spoilers deploy in order to decelerate the aircraft at 3 m/s² (9.8 ft/s²).
–> MAX : MAX mode is normally selected for takeoff.
In the case of an aborted takeoff, maximum pressure goes to the brakes, as soon as the system generates the ground spoiler deployment order.
–> ON : The blue ON light comes on to indicate positive arming.
–> DECEL : The green DECEL light comes on when the actual deceleration is 80 % of the selected rate.
Q37. On the WHEEL page, if AUTO BRK is displayed in green, what is indicated?A37. It indicates that the AutoBrake is armed.
Q38. What is the meaning of a flashing green AUTO BRK Memo on WHEEL page?A38. A flashing green AUTO BRK memo on WHEEL page comes on for 10 s after autobrake disengagement
Q39. What is the meaning of green DECEL light on the auto brake pushbutton?A39. The green DECEL light comes on when the actual deceleration is 80 % of the selected rate.
Q40. When is brake pressure applied to the brakes during landing using the LO setting? MED?A40. When using LO setting, pressure is applied to the brakes 4 seconds after Ground Spoiler Deployment whereas in MED setting, pressure is applied to the brakes 2 seconds after Ground Spoiler Deployment.
Q41. When do you select MAX mode on auto brakes?A41. MAX mode is normally selected for takeoff.
Q42. On slippery runways, antiskid operation may prevent reaching the predetermined deceleration, and the DECEL light will not illuminate. Is the auto brake still operative?A42. Yes.
Q43. What happens to the other brake modes when parking brakes are applied?A43. When you set the PARK BRK control switch to the ON position, this deactivates the other modes.
Q44. Where does the crew look to confirm that the parking brake is ON?A44. The ECAM memo page displays "PARK BRK".
Q45. What is the maximum allowable brake temperature for takeoff with brake fan?A45. 150 Degrees Celsius.
Q46. At what groundspeed the antiskid system is automatically deactivated?A46. Below 20 Knots.
Q47. When using the alternate brake system on accumulator pressure only, how many brake applications can the pilot expect?A47. Accumulators are designed to supply at least seven full brake applications.
Q48. How long will the accumulator maintain adequate parking break pressure?A48. The accumulator maintains the parking pressure for at least 12 h.
Q49. Which hydraulic system does the parking brake use?A49. Yellow Hydraulic System.
Q50. What system pressure is indicated on the BRAKES & ACCU PRESS Indicator?A50. The following are the indications on the BRAKES & ACCU. PRESS indicator :-
–> ACCU PRESS. : Indicates the pressure in the Yellow Brake Accumulator.
–> BRAKES : Indicates the Yellow pressure delivered to the Left and Right Brakes, as measured downstream of the alternate servovalves.
Q51. At the gate you notice brake temperatures above 300°C, you then select BRAKE FANS ON, when should the pilots turn the BRAKE FANS OFF?A51. Select brake cooling fans OFF when brake temperature decreases to approximately 250°C.
Q52. What is the maximum gear retraction speed VLO?A52. 220 Knots.
Q53. What is the maximum gear extended speed VLE?A53. 280 Knots/ M0.67 .
Q54. What is the maximum gear extension speed (VLO)?A54. 250 Knots.
Q55. What is the maximum gear extension altitude?A55. 25,000 Feet.

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