systems: engines Flashcards
engine description
TILTID
TAE125-02-99 (Thielert)
Inline configuration
Liquid cooled
Turbocharged
Indirect drive
Diesel design
inline configuration
the pistons are arranged in a straight line
liquid cooled
uses engine coolant to manage temps
refer to diagram for specifics
turbocharged
turbo normalizer allows engines to maintain sea level performance up to 6000 ft pressure altitude
refer to diagram for specifics
indirect drive
a gearbox reduces crankshaft rotation to propeller rotation
ratio is 1:1.69
is prop is 2300 rpm, engine is 3900 rpm
diesel design refers too…
category of internal combustion engine
ignition
Jet A or diesel fuel
fuel is injected after air is compressed
compressed air is HOT and fuel ignites without spark plug
starter system
main ship battery provides power to starter motor via battery bus
each engine has its own starter motor
glow plugs help in a cold start
glow plugs
glow plug heats combustion chamber to help start a cold engine
glow plug activates when turning on engine master switch, after it turns off the engine starter can be engaged
glow plug circuit breaker not accessible to pilot
when performing an air start…
not above 8000 ft
prop should windmill at 80 kts
do NOT engage starter is prop is windmilling
alternate air intake
controlled via a white lever switch
alternator air is sent through a foreign object debris filter
turbocharger & exhaust
provides sea level pressure performance up to 6000 ft press. alt.
air is compressed (by a compressor) and cooled (by an intercooler)… creates dense air
compressor is driven by turbine, which is driven by exhaust gases
waste gate allows exhaust gases to bypass the turbine… it’s completely closed at 6000 ft press. alt.
oil for the engine
oil cleans, coats, cools, and seals various engine components
wet-sump system
oil is cooled by a cooler
oil in sump -> engine -> oil cooler -> sump
oil pump moves the oil ^
coolant system
heat is transferred from cylinders to a coolant, which is then cooled by a radiator
bypass line: allows engine to warm up quickly
radiator: cools liquid
coolant heat exchanger: feeds cabin heat and defroster
to adjust system pressure: expansion tank and pressure relief valve
describe the propellor
three blade
wooden
controllable pitch
constant speed
full feathering
unfeathering
mac overspeed is 2500 rpm (no more than 20 seconds)
propellor construction
wooden core
reinforced pastoral coating
stainless steel edge cladding
controllable pitch
pilots ability to control RPM by changing blade angle
done indirectly through ECU
oil flows in/out of propeller hub to move pistons to change blade pitch
variable speed
automatic adjustments to maintain constant RPM throughout attitude changes
done by ECU and prop. governor valve
flywheels -> spring -> moves a “wall” -> oil flows in/out of prop hub -> pistons move -> blade angles change accordingly
full feathering
counterweights opposes windmilling forces and drives blades towards coarse pitch
a spring decompresses to ensure feathering position (81 degrees)
to feather: power level IDLE, engine master OFF -> opens governor valve -> oil flows back from the prop. hub -> pistons move -> blades feather -> electric valve at the pressure accumulator closes -> oil pressure is restored in the accumulator
unfeathering
engine master switch ON -> opens electric valve at the pressure accumulator -> pressure stored in the accumulator will move the propeller blades to low pitch -> propeller starts turning -> gearbox oil operates -> accumulator gets refilled
what does the gearbox do
gears down the propellor
engine at 3900 rpm, prop at 2300 rpm
reduces noise and increases efficiency
start lock
prevents full feathering on ground
feather pins extend below 1300 rpm
pins prevent pistons in prop hub from turning blades
applying takeoff power removes pins
overspeed
prop overspeeds is more than 2300 rpm
can withstand temporary overspeed up to 2500 rpm up to 20 seconds
reduce power in event of an overspeed (consult POH if this does not solve the problem)
