11.13 Flashcards
What are the characteristics of tail wheel configuration landing gear?
-on propellor driven/ light aircraft
-the main gear is forward of the CG
-a tail wheel is articulated
-steering is done through differential breaking or rudders
What are the characteristics of tricycle landing gear?
-the most commonly used
-CG is ahead of main landing gear
-ground looping is prevented
-nose over won’t occur during breaking
-forward vision is not obscured
-reduced drag at take off
What are the characteristics of tandem landing gear?
-two sets of wheels in line
-aircraft/ gliders use it
What is the trunnion link?
The hinge which the landing gear are on
What is the structure of the shock strut?
An outer and inner cylinder filled with hydrogen and nitrogen and capped at each end
What is the function of the upper and lower torsion link?
Connected to the inner moving cylinder they allow the shock strut to extend but not past the max
What is a torsion link damper?
Counteracts wheel shimming
Why may some landing gears need shortening on retraction?
They can be too large for sufficient engine to to surface distance
What is the point of the shock struts?
Absorb and transfer force to the fuselage
What are the two main classes of shock absorbers?
-solid (a spring metal/rubber)
-oleo pneumatic (fluid spring with gas oil or both)
What is the function of the gas or oil separator in an oleo pneumatic strut?
-when on ground the gas inside the lower cylinder is compressed
-during take off the weight of the aircraft is progressively unloaded the fluid in the upper chamber is slowly let into the lower
-the opposite occurs on the landing
How are main gear shock struts serviced?
With nitrogen gas and hydraulic fluid
Gas pressurising must be done with weight on wheels
What systems are used to extend landing gear?
-electrical
-pneumatic
-most commonly hydraulic
What is the purpose of detents in the lever for retraction and deployment of landing gear?
It prevents vibration lowering the gear
What is the importance of sequencing in terms of landing gear?
It ensures the doors and wheels are deployed correctly
How is retraction on ground avoided/ prevented?
-detents avoid accidental retraction
-a solenoid operated latch stops the lever being moved
What process occurs on retraction?
-down locks are pressurised and unlocked
-the gear actuator are pressurised through an unrestricted orifice check valve
-sequence valve A&B are open when doors are opened which allows fluid flow out of extension piston
-squeeze valve C&D receive fluid pressure allowing the gear doors to close when the gear is stowed
When is emergency extension used on landing gear?
After a main hydraulic systems failure
How does emergency extension work?
Up locks withdrawn which allows them to fall under gravity and lock
In some cases electrical or compressed gas is used
What must be done before emergency deployment?
Normal landing gear placed in off position to prevent hydraulic locking
What are the two common gear indications on modern aircraft?
-indicator lights near the control lever shows the position of the gears
-ECAM/EICAM shows positions of doors and gear
What indicates gear position in the flight deck?
Green light = down and locked
Red light = unlocked or travelling
No lights = up and locked
What is a micro switch?
Open and close an electrical switch very rapidly
How is a micro switch used in landing gear?
The micro switch is located on the landing gear control lever mechanism which is in circuit with gear position sensors, a red light shows when there is a disagreement
