11.13 Flashcards
Whats the three configuration for main landing gear ?
Tail wheel
Tricycle - type
Tandem
Explain a tail wheel configuration ?
Main gear is located forward of the Centre of gravity.
Explain tricycle configuration ?
Centre of gravity is positioned ahead of main landing gear.
Whats 3 advantages for a main landing gear tricycle configuration ?
-Provides stability
-Allows more forceful application of the brakes without nosing over.
-Forward vision isn’t obstructed
Explain tandem landing gear configuration ?
Landing gear is installed back to back on the longitudinal axis
Landing gear is positioned forward and aft the centre of gravity
( glider plane )
What does a Main landing gear assembly consist of ?
Shock strut
Side strut
Drag brace
Downlock assembly
Uplock assembly
Trunnion
Actuator
Torsion link
Wheel and tyre
What does the trunnion link connect ?
Top of leg to the wing structure
( allows leg to rotate into and out of the landing gear )
Whats the two telescopic cylinders a shock strut has ?
Outer cylinder
Inner cylinder
What is has each cylinder filled with ?
Hydraulic oil and nitrogen
What does the torsion link connect ?
Connect the inner moving cylinder of shock strut to fixed outer cylinder.
What does the side strut resist ?
Sideways movement
( connected to upper side of aircraft structure and on the other side, via a joint to the shock strut )
Whats the drag struts function on the landing gear ?
Provides longitudinal support
Whats the function of a gear down-lock mechanism ?
Ensures gear doesn’t fold when extended
When are the locating cams not engaged on the nose landing gear ?
When the weight of the aircraft is on the wheels.
( engagement of cam ensures wheels are at 90 degrees )
What does a steering actuator do ?
Rotates nose landing gears inner cylinder which turns the wheel
What controls the impact force n an aircraft during landing ?
Shock absorber
Whats the two main classes of shock absorbers ?
Solid
Oleo
How does a solid shock absorber absorb the landing impact ?
Via a spring made from steel
How does an oleo shock absorber absorb the landing impact ?
Using Fluid spring with gas or oil, or mixture of two
How are the gas chambers and oil chamber separated ?
By a piston
( this type of separated oleo is called a - Oleo-pneumatic strut with separator )
Whats the two types of oleo?
Oleo with separator
Oleo without separator
Whats the two principles that allow a shock absorber to transfer the landing impact to the fuselage ?
Converting energy into heat energy
Transferring throughout airframe at different rates than the single strong pulse of impact.
Whats the purpose of the restricter valve in the outer cylinder on an aircraft’s landing gear ?
Compresses the gas which doesn’t allow the inner cylinder to suddenly move up into the outer cylinder, instead it slows the movement down. This is done by the use of a flutter plate
What gas are main gear shock strut serviced with ?
Nitrogen gas
What should be done for shock strut servicing ?
Strut dimension X and gas pressure is measured.
When the landing gear lever is placed to off after retraction, what does this do ?
Depressurised system and cuts off hydraulic pressure supply.
During gravity extension of the gear, do the doors close ?
No. They stay open.
how does the gravity extension gear fall in a controlled speed and doesn’t swing violently down ?
Due to selector valves in the hydraulic system connecting the pressure and return lines.
If the landing gear warning indicators fail, Whats an alternative way of checking for full extension and locking ?
Gear down lock viewers
( located in the floor under access panel and you must check for red alignment marks which means thy have locked )
Whats two landing gear positions indication systems ?
Indicator lights near gear lever
ECAM ( airbus ) or EICAS ( Boeing )
-these position doors and gear
What is a Microswitch’s function on the landing gear ?
Connected from lever to the gear position sensor and determines weather they both show the correct position
( red indication light illuminated shows that there is a disagreement between the control lever position and position of the landing gear/ door )
Whats a micro switch ?
Device which opens and closes an electrical circuit.
Whats a proximity switch ?
Used over micro switch where there is a high chance of contact corrosion due to dirt etc
Whats the 2 types of proximity switches ?
Reed switch
Electronic switch
What does a proximity switch consist of ?
Target
Sensor
Explain the operation of a reed switch ?
Consists of 2 spring loaded contacts in glass tube
Contacts are closed by magnetic flux
Electric circuit is closed and operates switching function
Explain does a electronic proximity switch consist of ?
Consist of sensing coil and non-magnetic target
How is the wheel supported ?
On axial by a tapered bearing.
What are aircraft wheels usually made from ?
Aluminium and magnesium alloy
What attaches the inboard half and outboard half together ?
Tie bolts
What absorbs the heat cause from the brakes on a wheel ?
Heat Shield found in between outboard and inboard half of the wheel ?
What happens if the heat shield experiences a harsh braking force which generates a lot of heat ?
It can’t take the heat so its uncontrollably distributed to wheel which can cause tyre to burst
Where is the inflation valve located ?
Outboard half
Whats found at the inboard half of the wheel ?
Heat shield
Brake unit
Fuse plug
Whats the 3 types of aircraft brakes ?
Single disc
Dual disc
Multiple disc
How are single disc brakes engaged ?
Friction between both sides of a calliper
When are dual discs used ?
When the aircraft requires more braking force
Whats located between the two discs ?
Centre carrier
What do stators and rotors provide on a multiple disc ?
Provide friction surfaces for braking effect
( burning braking, stators and rotors are squeezed together between pressure plate )
How much longer do carbon brakes last then steel brakes ?
20-50 %
Whats the 3 main functions brake pistons fulfil ?
Apply brake force
Compensate for wear of brake
Adjust brake clearance
What provides the supply of hydraulic pressure to apply the bakes I large aircraft that do not have a master cylinder ?
Power brake control valve
( meters hydraulic fluid to the corresponding brake assembly matching the pressure applied to the pedal )
What provides the supply of hydraulic fluid to apply the brakes on a light aircraft ?
Master cylinder
( when pedal is depressed, master cylinder forces hydraulic fluid through a line to the pistons in the brake assembly )
Why would a brake debooster be installed ?
If you don’t need all hydraulic pressure to use the brakes
How does a parking brake work ?
Brake pressure is remained in brake system due to a shutoff valve in the return line.
( done by hydraulic accumulator pressurised by nitrogen )
Whats emergency backup options for brake systems ?
Separate hydraulic power source
Brake accumulator.
Where are brake temps and overheat warnings displayed ?
ECAM - airbus
EICAS - Boeing
What does the anti-skid system do ?
If it detects that the wheel speed and aircraft speed is different, brake pressure is not directed to piston and instead is directed to the return
What does touchdown protection prevent ?
A tyre blow out upon landing by not allowing brakes to be applied until aircraft’s wheels have touched down onto the runway.
( anti-skid valve connects system to return until there is weight on wheels so that the brakes cannot be operated )
When does the auto-brake system begin to work ?
When there is weight on wheels and thrust reversers are deployed
What’s the bead function on a tyre ?
Strengthen the carcass and mount tyre to wheel
Whats the carcass ply’s function on a tyre ?
Give tyre strength and is layered
Continue tyre properties
What does a shimmy damper do ?
Dampens oscillations and found on upper torque link on nose gear
What does having main landing gear steering reduce ?
Tyre scrub `
Why is there a pin inserted in to the nose wheel ?
Isolates nose wheel from cockpit controls which doesn’t allow pilots to move the wheel.
( steering commands doesn’t reach actuators )
Where is the air/ground sensor installed on an aircraft ?
On the upper Torino link and sometimes on the collar
Explain a load sensor to determine weather the airplane is in the air or on the ground ?
Senses the landing gear beams bending when the weight of the aircraft is on the gear
