Propellers Flashcards
Describe the propellers
four blade, spring loaded, hydraulically operated, counterweighted, full feathering
Where does the propeller RPM gauge get its power?
Self generating power
Minimum prop idle
1,150 rpm
What is the rpm during takeoff?
2000rpm
What is the rpm during cruise?
1,600rpm
What is the maximum rpm in reverse?
1,900rpm
Describe the Primary Governor
Adjustable.
Green arc from 1600-2000rpm.
Uses engine oil pressure boosted by 200psi.
Decrease in oil pressure increases pitch (toward feather).
Describe the Overspeed Governor
Protects against failure of the Primary Governor.
Not adjustable.
If primary fails, limits RPM to 104% of Primary max value (2080rpm).
Test using GOV TEST switch.
Describe the Fuel Topping Governor
Protects against failure of the prop hub system.
Attempts to limit prop rpm by reducing engine speed.
If the primary governor is unable to control prop rpm, the FT governor will limit fuel flow to engine.
106% of selected N2 in flight
95% of selected N2 in reverse
Describe Synchrophaser- Type I
Master and Slave
L engine is master
MUST be turned off for takeoff and landing
Why must Type I prop synch be turned off for takeoff and landing?
Master and slave system: if the L engine fails, the R will attempt to match, effectively cutting all power to the engines
PROP SYNCH ON
Landing gear handle position down
Prop synch on
Type I only
Describe Synchrophaser- Type II
NO master and slave: speeds up slow prop
MAY be left on for T/O & LD
NO annunciator
Describe Autofeather
automatically feathers if torque falls below 260 ft/lb
Maximum transient rpm
2,200 (5 secs)
Normal Maximum rpm
2,000rpm
Maximum rpm with failed Primary Governor
2080
Prop overspeed test range
1830-1920 rpm
What happens below 400 rpm with autofeather on?
Autoignition is turned on.
Opposite autofeather is turned off.
What happens at 260 rpm with autofeather on?
Propeller feathers
Why don’t we retard the power lever to confirm an engine failure?
It disarms the autofeather
Why is max reverse rpm 1900?
FCU air pressure is bled-off by the Fuel Topping governor to limit prop rpm
