Cap 6 Landing Gear

Question 1

Landing gear

Answer 1

Absorb the forces imposed by landing
Supoort weight
Allow ground manouvering
Withstand side loads
Give minimal friction between a/c and the grouns

Answer 2

Rubber bungee design
Cantilever design

Retractable
~NOSE GEAR
~MAIN GEAR
~BOGIE GEAR

Question 3

THE OLEO STRUT

Answer 3

~OLEO STRUTS,ARE HYDRO PNEUMATIC ABOSRBES THAT REDUC AND ABOSRBS THE STRESSES ENCOUNTER DURING LANDGING

~STRUT INCORPORATES A HYDRAULIC DAMPER VALVE AND A SEPARATE PISTON
~THE DAMPER CONTROL THE FLOW OF OIL WHICH REGULATES THE RATE OF COMPRESSION (BUMP) AND EXTENSION (REBOUND)
~THE UPPER MOST SECTION IS NITROGEN FILLED ,THE COMPRESSES NITROGEN ACTS AS A SPRING
~ON GROUN NITROGEN AND OIL PRESSURE ARE EQUAL
~THE NITROGEN BEARS THE WEIGHT OF THE A/C WHEN IT’S ON THE GROUND

THE OLEO IS USUALLY FILLED WITH DTD585 (RED COLOUR)

Question 4

Nose wheel assembly

Answer 4

~retraction actuator
~side brace
~torque link
~taxing lights
~steering actuator
~oleo strut

Question 5

Main landing gear assembly

Answer 5

~upper sidestay
~retracting extension actuator
~locking links
~locking actuator
~shock strut
~torque links
~bogie beam
~low sidestay
~inner door 
~door up lock
~door retraction actuator

Question 6

Nose wheel requiremtns

Answer 6

~free castoring to allow steering by differential braking
~automatic self centering to allow the nose wheel to return to a central position (longitudinal) prior to retraction
~shimmy protection via a dedicated anti device

Withstand&raquo_space;landing,taxing,manouvering

Question 7

Gear locks -up locks

Answer 7

During emergency operation the up lock is released mechanically

Answer 8

Limitation,operattion ,indication

Question 9

Alternative indication

Answer 9

~Some older sys use a “dollys eye” sys of visual indicators
~Some a/c indictae emergency down with all red and green lights illuminated
~door indicator light show when a door is in an unsafe or open condition
~indicator bulbs must have two filaments for redundancy

Question 10

V speeds

Answer 10

~V LO - velocity landing gear operating
~V LE velocity landing gear extended

On most a/c V LO is lower than V LE
This is due to the gear doors being open during operating phase

Question 11

Emergency extension

Answer 11

~hand crank
~compressed nitrogen to blow the gear down
~gravity fall

~a manual operated handle
~release up locks
~open safety valve
~gear descends under gravity
~over centre locks ensure the gear is down,locked and safe

Question 12

Nose steering (light a/c)

Answer 12

~Differnetial brqaking
~rudder pedal
~mechanical linkage between nose wheel and rudder bar
~tiller operation
~small electric motor 
~tiller is only for low speed

Question 13

Nose steering( large a/c)

Answer 13

~A tiller provides max 75 degrees steering in either direction
~Body steer reduces tyre scrubbing caused by being dragged sideways
~the greatest force will be felt on the gear leg inside the turn and the force is amplified through the scissor link which places a huge turning force between the inner and outer oleo’s

Question 14

Nose self centre

Answer 14

During ground operations ,a self centreing steering mechanism ensures the a/c follows a straight path until a turn in deliberately induceed

Question 15

Wheel shimmy

Answer 15

Lateral oscillation along the longitudinal axis or wobble

Prevention»
~shimmy damper ,hyd cylinder acting as a damper
~dual nose wheel ,provide two point of contact
~maarstand tyre , provide two point of contact

Faults than can effect shimmy:
~worn or broken torque links
~wear in the wheel bearings
~low or uneven tyre pressures

Enter in tech log if there is suspected shimmy