14 Landing Gear

Question 1

What inputs does air/ground sensing system use to configure the airplane systems to the appropriate air or ground status?

Answer 1

Air/ground logic signals from sensors located on each main landing gear beam.

Question 2

a. What does the landing gear consist of? b. Which elements are steerable?
c. How many wheels are there on each main truck?

Answer 2

a. Two main landing gear and a single nose gear b. Nose gear

c. Four

Question 3

Which hydraulic system powers the landing gear?

Answer 3

The Centre system

Question 4

a. What condition removes the lever lock?

b. What action is required to raise the gear if the lever is locked?

Answer 4

a. Air/ground sensing

b. Pushing and holding the landing gear lever LOCK OVERRIDE switch

Question 5

a. After retraction, how is the gear held up? b. Is the system still pressurised?

Answer 5

a. By uplocks
b. No, the system automatically depressurises after the gear is retracted
and all doors close

Question 6

What is the normal sequence of EICAS gear position indications during a retraction?

Answer 6

Green DOWN changes to white cross-hatch during transit. When gear is up, indication changes to UP for 10 secs and then blanks.

Question 7

During alternate gear extension what releases the gear doors and uplocks?

Answer 7

A separate dedicated DC powered electric hydraulic pump using Centre system fluid.

Question 8

When the alternate gear extension system is used, does the EICAS gear indication change?
14.GEAR

Answer 8

Yes, to the expanded gear indications.



Question 9

Do the doors close when the gear is down after an alternate selection?

Answer 9

No, the doors remain open.

Question 10

Can the gear be retracted after an alternate selection?

Answer 10

Yes, the landing gear can be retracted by the center hydraulic system, if it is operating, by selecting DN then UP with the gear lever.

Question 11

When is the Rudder Pedal Steering Disconnect switch used?

Answer 11

The switch is used during a flight controls freedom of motion check.

Question 12

What provides primary steering control?

Answer 12

Nosewheel steering tillers for each pilot.

Question 13

What is the greatest angle each will turn the nosewheel?

Answer 13

Up to 70d deg in either direction.

Question 14

What is the maximum nosewheel deflection using the rudder pedals?

Answer 14

Up to 8 deg in either direction.

Question 15

Is there any relationship between tiller and rudder pedal steering?

Answer 15

Yes, tiller inputs are summed with rudder pedal inputs

Question 16

What system powers the brakes?

Answer 16

The electrical system via four electric brake power supply units.

Question 17

How many Electric Brake Actuators (EBAs) are there on each landing gear wheel brake?

Answer 17

4

Question 18

The EBAs are controlled by Electric Brake Actuator Controllers (EBACs). How many EBACs are there in total?

Answer 18

4

Question 19

With RTO selected, when would the brakes be applied?

Answer 19

• the airplane is on the ground, and
• groundspeed is above 85 knots , and
• both thrust levers are retarded to idle

Question 20

For a normal landing when will the Autobrake system apply the brakes?

Answer 20

• both thrust levers are retarded to idle, and

* the wheels have spun up

Question 21

Which actions could disarm the Autobrake after landing?

Answer 21

• pedal braking applied
• either thrust lever advanced after landing
• speed brake lever is moved to the DOWN detent after the speed brakes have deployed on the ground
• DISARM or OFF position selected on the AUTOBRAKE selector.
• autobrake fault
• normal antiskid system fault
• loss of inertial data from the Inertial Reference Units (IRUs)

Question 22

Where are the brake temps displayed?

Answer 22

Wheel brake temperatures are displayed on the GEAR synoptic display.

Question 23

Where are the tyre pressures displayed?

Answer 23

Tire pressures are displayed inside each individual gear symbol on the GEAR synoptic.