Chapter 7: Landing Gear Systems Flashcards
what does main and nose landing gear do?
main: main support of large download forces, brakes installed here
nose: support weight and steering mechanism
3 types of landing gear configuration
1) tail/conventional
2) tandem
3) tricycle
tail/conventional configuration is used?
older aircraft on rough field ops
tricycle configuration is used due to?
1) more forceful brakes without nosing over, higher landing speed
2) better visibility from flight deck
3) prevent ground-looping of aircraft (a/c CG forward, keeps a/c moving forward)
what are aircraft wheels used for and material made?
support entire weight of aircraft
lightweight, strong alu alloy
function of aircraft tyres
1) supporting weight
2) absorbing shock
3) gripping contact with runway
4) discharge static electricity
what does a trunnion do?
allows gear to pivot during retraction and extension
what is a strut?
vertical member of the landing gear assembly
purpose of drag link/strut
provide support to shock strut and stabilise shock strut longitudinally
purpose of side strut/ brace link
stabilise landing gear laterally
purpose of overcenter link
prevent link from pivoting at joint except gear retracted > prevent collapse of gear during ops
how does overcenter link work?
locks the main gear only in the down position
what does a lock mechanism do?
“downlock” locks LG in down position, main LG is held up in by uplock mechanism
what does the axle do?
main wheels are supported and installed
how does non-shock absorbing LG work?
flexible struts that receives impact of landing and return it to airframe to dissipate at slower rate (gear flexes initially)
what fluid is used for shock absorbing LG?
nitrogen gas combined with hydraulic fluid
what are the upper and lower chamber filled with in the shock absorbing LG?
upper: nitrogen gas
lower: hydraulic fluid
what happens when LG is set to UP position?
1) unlock & open wheel well doors
2) unlock LG from downlock
3) retract LG
4) close doors
5) LG kept UP by uplock mechanism
what happens when LG is set to DOWN position?
1) unlock & open wheel well doors
2) unlock uplock
3) extend LG
4) close wheel well doors
Power Formula
W = PQ / η
what does the downlock mechanism do?
prevent retraction of LG when in DOWN position
how can the aircraft be steered?
nose wheel steering / differential braking
what does the cam assembly do in the LG system?
keep gear align, line up wheel and axle assembly in straight position, align with longitudinal axis
what does a shimmy damper do?
control nose wheel shimmy through hydraulic damping
nose gear tend to oscillate at certain speeds
how does emergency extension system work?
handle is pulled > releases uplock & allows gears to freefall to extended position by gravity
what does a safety switch do on the LG system?
positioned to open/close depending on extension/compression of main LG strut
what is a ground lock?
pin placed into holes of the gears to prevent it from collapsing
red tags attached to them “remove before flight”
what do the lights on gear indicator mean?
green: down and locked
red: in transit
no light: up and locked
what does a warning horn do?
sound off when LG is not down & locked when landing
what does a torque link do?
keep the wheels aligned
what are 2 indications that the LG is not safe?
1) red light in LG indication
2) warning horn
