11.13 Landing gear

Question 1

What are the advantages of a nose tricycle gear system over a tail system?

Answer 1

• Directional stability
• Higher landing speeds (better braking ability)
• Greater decrease in lift after touchdown (less AOA on wings)
• Better visibility during takeoff and landing

Question 2

What type of undercarriage will give a larger footprint?

Answer 2

Multiple bogies

Question 3

What part of the undercarriage supports the aircraft weight?

Answer 3

The shock strut

Question 4

What function does the gas fulfil in a shock absorber?

Answer 4

It acts as the spring to absorb the shock

Question 5

What characteristics will a shock absorber display if it is overfilled with oil?

Answer 5

It has harsh operation (insufficient spring)

Question 6

What two internal components of a shock absorber provide damping during extension?

Answer 6

• Laminar flow orifice

- Tapered metering pin

Question 7

What component will transfer vertical load to the airframe without impacting torque?

Answer 7

Spherical bearing

Question 8

What is the purpose of angling the nose gear leg forward of vertical?

Answer 8

Nose wheels castor to centre

Question 9

How is landing gear prevented from lowering in high speed?

Answer 9

A mechanical lock or speed signal which causes a safety valve to isolate the hydraulics

Question 10

When will the autobrake system disengage?

Answer 10

When the pilot uses the brakes

Question 11

What is the principle of operation if a wheel speed transducer?

Answer 11

It converts the rotational speed of the wheel into an electrical signal

Question 12

What component will close if the brake line pressure differential gets too high?

Answer 12

The hydraulic fuses

Question 13

What effect will thrust reverse have on the auto braking system?

Answer 13

The auto brake will reduce brake pressure to keep the pre-selected deceleration rate

Question 14

When would a flat spotted tyre require changing?

Answer 14

When there is shimmy on braking or it’s worn to limits

Question 15

What is the purpose of the drive keys on a wheel?

Answer 15

So the wheel can drive the brake discs

Question 16

The landing gear shortening mechanism will do what?

Answer 16

Shorten the main gear for retraction into the wheel well

Question 17

What is the cockpit indication that all landing gear is stowed and locked?

Answer 17

No lights

Question 18

How is nose wheel steering achieved on a large commercial aircraft?

Answer 18

• By the use of a steering tiller that sends electrical signals to a hydraulic steering control valve
• By the use of a steering tiller to mechanical linkages to a hydraulic steering valve

Question 19

How can undercarriage retraction tests be carried out on 1 leg only?

Answer 19

By leaving downlock pins in position

Question 20

Which part of an undercarriage leg ensures it remains down and locked?

Answer 20

Down lock mechanism (geometric lock and actuator)

Question 21

Which part of an undercarriage leg absorbs the load on landing?

Answer 21

The shock strut

Question 22

What are the component parts of a heat stack in the braking system?

Answer 22

Rotors and stators

Question 23

On a power braking system, what component ensures demand is met at the unit?

Answer 23

The brake metering valve

Question 24

The support strut of the undercarriage carries what load?

Answer 24

The weight

Question 25

How is damage to the steering mechanism prevented when towing?

Answer 25

Bypass valve

Question 26

How is the undercarriage leg held in the up position?

Answer 26

By the use of an up lock

Question 27

In which direction do the plies of a conventional tire run?

Answer 27

Cord plies run diagonally

Question 28

Why is there a minimum turning radius applied to aircraft during towing or taxiing?

Answer 28

To prevent damage to the undercarriage and tires

Question 29

What is the purpose of the torque link on an undercarriage leg?

Answer 29

They permit the inner cylinder to move up and down in the outer cylinder but prevent it turning

Question 30

Apart from the lock pins, what else prevents the undercarriage from retracting on the ground?

Answer 30

The landing gear selector cannot be selected up without overriding the lever lock

Question 31

What would occur if the anti-skid system detects a locking wheel?

Answer 31

A full release signal is sent to the brakes by the locked wheel sensor allowing the wheel to rotate. The skid detection system can then regulate the braking again

Question 32

What is the position of the main undercarriage doors once the main undercarriage has been extended?

Answer 32

Normally closed

Question 33

Why should a wheel be deflated before removing from the axle?

Answer 33

To prevent high pressure splitting of the wheel

Question 34

What would occur if a wheel assembly was subject to an overheat situation?

Answer 34

Fusible plugs would melt

Question 35

In which direction should a wheel be approached for servicing?

Answer 35

In front or behind