14 - Landing Gear

Question 1

LANDING GEAR

1. Which hydraulic system(s) is used to raise and lower the landing gear normally?

Answer 1

System A

Question 2

2. How are the wheels protected from thermal expansion?

Answer 2

4 thermal-relief fuse plugs in each inner wheel

Question 3

3. What is the purpose of the supplemental landing gear indicator lights on the aft
   overhead panel?

Answer 3

They use separate circuitry and lights to provide redundant gear-down indications

Question 4

4. What is the purpose of the lever lock override?

Answer 4

Bypasses the landing gear lever lock to allow the control lever to be moved to the UP position

Question 5

5. What is the purpose of the frangible fitting on the main wheel wells?

Answer 5

To protect the wheel well from loose tread on a spinning tire. If a spinning tire with loose tread impacts the frangible fitting, the FF valve opens and relieves hydraulic pressure from the retraction line and the gear free-falls back into the down position

Question 6

6. What is the purpose of the landing gear transfer valve?

Answer 6

A component of the Landing Gear Transfer Unit (LGTU) which uses B system pressure to assist hydraulic system A with gear retraction in the event of a #1 engine failure

Question 7

7. How is the landing gear lowered in the event of a loss of hydraulics?

Answer 7

Using the manual extension system

Question 8

8. Which system powers nose wheel steering?

Answer 8

Normal NWS = A system
Alternate NWS = B system

Question 9

9. With the loss of hydraulic system A and B, how is braking accomplished? Are there any limitations?

Answer 9

Brake accumulator pressure moves the accumulator isolation valve, allowing accumulator pressure from the brake accumulator to the normal brake system

Question 10

10. Are autobrakes available on the alternate brake system?

Answer 10

No, only on the normal brake system

Question 11

11. What conditions must be met for RTO braking to activate?

Answer 11

• Autobrake Armed (RTO)
• Thrust levers to IDLE
• Wheel speeds greater than 88 kts

Question 12

12. Which system(s) provide pressure to the parking brake?

Answer 12

• Hydraulic system A or B, or
• Accumulator

Question 13

13. What is the purpose of the Proximity Switch Electronic Unit (PSEU)?

Answer 13

Provides;
- Air/ground sensing
- Landing gear position indications & warnings
- Landing gear transfer valve control
- SPEADBRAKES EXTENDED light control
- Takeoff warning horn & TAKEOFF CONFIG light control
- Door Warning System
- Flight Control indication (flap/slat)
- Stall management yaw damper inputs
- Tailskid control