11.13 Landing Gear Flashcards
What are the disadvantages of tail wheel?
Obscured vision
High drag before tail lift
High risk of nose over
What is a bogie assembly?
Multiple wheels on a gear rather than single or double.
What is a structural fuse pin?
Pins designed to shear in the event of overload.
What is the torsion link damper used for?
Counteract wheel shimmy
What are the main components of a shortening mechanism?
Adjustable link
Bellcrank lever
Connecting link
Upper and lower link
What two classes of shock absorber are there?
Solid- solid spring made of steel or rubber
Oleo pneumatic- fluid spring with gas or oil
What is hydraulic dieseling?
Occurs when air mixes with hydraulic cylinder oil. The air forms bubbles in the hydraulic oil.
What happens when there is too much oil in the oleo?
The shock strut operates too harshly
Why are the brakes applied when the gear is moving up or down?
To avoid the gyroscopic effect.
How is the life of the landing gears hydraulic components and prevents leakage?
The selector valves shut off the pressure supply and open the return lines and the brakes are released.
What are friction bands or pads installed for?
To stop the wheels from spinning after retraction
In small aircraft how are the gear extended when air loads alone are not enough?
They can be cranked by the pilot
What does a green light represent in terms of gear position?
Down and Locked
What does a red light represent in terms of gear position?
Unlocked or travelling
What does no lights represent in terms of gear position?
Up and locked
When are prox switches used instead of microswitches?
When there is a high risk of contact corrosion due to dirt and moisture.
What two types of prox switch are used on aircraft?
Reed and electronic switch
What does a reed switch consist of?
Two spring loaded normally open contacts
What melting temp does a red fusible plug have?
155 degrees c
What melting temp does a green fusible plug have?
177 degrees c
What melting temp does a yellow fusible plug have?
199 degrees c
What bearings do aircraft wheels have?
Tapered roller bearings
What should brake fires be extinguished with?
Dry powder
What aircraft use single disc brakes?
Light Aircraft
On a dual disc brake what is between the two discs?
Centre carrier
What are the main components of multiple disc brakes?
Piston housing, torque tube and heat pack
What is the advantage of carbon heat packs over steel?
40% lighter and can take 50% higher heats
Last 20-50% longer
What three jobs does a brake piston have?
Apply force
Compensate for wear
Auto adjust
What is the piston clearance?
Distance between piston and spring sleeve
What does 1mm of wear equate too?
20-30 landings
What does the torque tube do?
Transmits the torque of the stator discs to the piston housings
What is the key element in a power brake system?
Brake metering valve
What was the first dunlop maxaret system known as?
ABS
When is anti-skid inhibited?
Below 25 knots
What are type I tyres?
Used on fix gear with a nominal diameter of 27” found on older aircraft
What are type III tyres?
Light aircraft with a landing speed of 160 mph.
How does the type III tyre number system work?
First- Nominal section width
Second- Diameter of rim
What is a type VII tyre?
Found on jet aircraft
What is a type VIII tyre?
Used on large aircraft, designated by three numbers.
What is a radial type VIII designated by?
Letter R
What angle is bias ply?
30-60 degrees
What angle is radial ply?
Right angle to rotation
What 4 parts of a tyre are there?
Bead
Carcass plies
Tread
Sidewall
What are the beads?
High tensile strength steel wires embedded in the rubber
What are the green or white dots on a tyre?
Awl markings, seepage vents to allow seeping gas to escape
What is the red mark on a tyre?
Balance mark
What should the red mark line up with?
Align with the heavy spot (normally the valve)
What is a rib tread good for?
Paved surfaces
What is a diamond tread good for?
Unpaved runways
What is an all weather tread?
Rib combined with diamond
What is a smooth tyre tread good for?
Older aircraft without brakes
What is a chine tyre?
Used on the nose gear of aircraft with fuselage mounted engines.
When is rib tread worn?
Less than 2mm depth for more than 25% circumference
How many times can a tyre be retreaded?
10 times
When does a dry braking flat occur?
When the tyre is locked from rotation while the aircraft is in motion.
How does wet braking flat appear?
Almost like its been melted.
What must happen to a tyre when it is 80% its inflation?
Be removed along with any other tyre on its axle
When does tread chunking occur?
Turning or taxiing quickly
What is the general size of chunking allowed?
7cm squared
What must happen if a tyre has an open tread joint?
Tyre must be removed
When does lateral scoring take place?
When a tyre encounters sideways movement i.e. crosswind landing
What is the max size of tread cut allowed?
35mm
What must happen if a tyre is exposed to a contaminant up to 12 hours?
Washed off asap, over 12 hours and it must be sent away.
What is the storage pressure of tyres?
20-30 psi
Aircraft with castor type nose gear steer using what?
Differential braking
What is surface effect dampening?
Used in a non-hydraulic shimmy dampener, rubber piston rubs on the cylinder.
What do smaller aircraft use instead of cams to align the nose gear on retraction?
Guide pin
When the nose gear is steering 70 degrees what can the main gear twist by?
5-8 degrees
On large aircraft what does the bogie angle used for?
WOW sensing
