Landing Gear

Question 1

A/c l/d gear layout and config

Answer 1

Categorised according to the posn of the subsidiary wheel

Question 2

Disadv of a taildragger/tailwheel

Answer 2

High drag on t/o

Can over brake

Question 3

Adv of a tricycle undercarriage

Answer 3

Better cockpit vis 
Easier to control on especially in x winds
Less likely to nose over 
Braking is more straight fwd 
Less drag on t/o

Question 4

Common types of l/d gear

Answer 4

Spring steel leg
Cantilever - supported at 1 end only
Rubber cord or bungee
Oleo- pneumatic struts

Question 5

Torque links

Answer 5

Found on oleo-pneumatic l/d gear - stops the main plunger tube rotating inside the leg

Question 6

% of weight on nose gear

Answer 6

10%

Question 7

% of weight on main gear

Answer 7

90%

Question 8

Definition of bogies

Answer 8

4 or more wheels on a bogey beam

Could also be called truck or set

Question 9

Typical main wheel arrangements

Answer 9

Single
Tandem
Double
Bogie

Question 10

Main disadvantage of a bogie

Answer 10

Large footprint of a bogie unit will cause the unit to crab whilst turning

Question 11

Main types of wheel attachment

Answer 11

Cantilever - for light a/c

Forked, Half forked - stronger, for heavier a/c

Dual - load spread over 2 wheels

Question 12

% of shock absorbed by shock absorbers

Answer 12

90%

Question 13

Oleo pneumatic the use of nitrogen gas

Answer 13

In the main plunger - acts as a spring to absorb the loads

Question 14

Oleo pneumatic- oil

Answer 14

In the main body to dampen the spring action

Question 15

Oleo pneumatic - most likely cause for the fescalised portion being too small is

Answer 15

The shiny bit

Low gas n2 pressure

Could result in bottoming-out on l/d

Question 16

Oleo pneumatic - oil

Answer 16

If oil levels are too low the rebound is not properly damped

Question 17

Purpose of the shortening mechanism

Answer 17

Shortens/lengthens the gear on retraction/extension

Question 18

Brake bars

Answer 18

Torque limiting - torque links sends a message to the braking system about heavy braking - prevents wheel leg bending

Question 19

An example of an additional load on the l/d gear

Answer 19

Towing = shear

Question 20

Creep - l/d gear

Answer 20

Unwanted movement of the screw jack - req a mechanical lock to prevent this on screwjack l/d gear

Question 21

Automatic self centring

Answer 21

Ensures the nose wheel is centred before it is retracted - needs to be for extension/retraction

Question 22

Castering

Answer 22

Allow stejering by differential braking

Question 23

Downlocks on l/d gear

Answer 23

Ensures that accidental retraction can’t occur

Question 24

Over centred geometric device

Answer 24

Used to lock gear down

Question 25

Retraction and extension is completed by

Answer 25

Selector valves

Question 26

The edge of the l/d gear door is

Answer 26

Frangible

Question 27

Solenoid latch

Answer 27

Prevents YOU from moving the gear lever while on the ground Info is sent through from the air/ground logic circuits - weight on wheels

Question 28

OFF posn on the l/d gear lever

Answer 28

Stops the pressuring of the gear system during flight

Question 29

When does the l/d gear warning horn activate

Answer 29

A/c is in the l/d config and 1 or more throttle levers are less than approximately 1/3rd open Continuous horn for l/d Interment horn for t/o

Question 30

VLE and VLO

Answer 30

VLE = max speed with the l/d extended VLO = max operating speed for the l/d gear - doors become the limiting factor

Question 31

The tiller can steer the nose wheel

Answer 31

75* left or right May be supplemented by body gear steering which reduces the tyre damage caused by scrubbing

Question 32

Shimmy definition

Answer 32

Rapid sinusoidal oscillation of the nosewheel and is divergent in nature

Question 33

Possible causes of shimmy

Answer 33

``` Uneven tyre pressure Unevenly worn tyres Unbalanced wheels Worn shimmy damper or wheel bearings Worn torque link will make things worst ```

Question 34

How to reduce shimmy

Answer 34

Hydraulic damper fitted Heavy self centring springs Double nose wheels Twin contact tyres - maarstrand twin contact tyre