Propellers Flashcards
Define the propellers on the MC-12.
Four-bladed aluminum propeller. Full feathering, constant speed, counter-weighted, reversible type, controlled by engine oil pressure through single action, engine driven propeller governor.
What does illumination of the (White) Prop PitchWarning indicate?
The L or R PROP PITCH annunciators are provided to inform the pilot of a blade angle more than 8° below the flight idle low pitch stop.
During normal ground operation, these annunciators will be illuminated. The system uses a magnetic proximity sensor to sense the position of the feedback ring and, thereby, the position of the propeller dome and blade angle.
When is the ground idle stop solenoid inactive?
above 68-70% N1 because it is above the mircoswitch.
What are the two essential functions of the Beta Valve?
Prevents the Prop from entering reverse un-commanded
Controls blade angle (& RPM) while in reverse
What is the blade angle when the props are at Ground Idle Gate?
2 degrees
As the blade angle _________, rotational drag increases, and the blade speed will ________?
increases, decrease.
As the blade angle increases, rotational drag
increases, and the blade speed will
decrease.
State the component(s) that cause(s) the blades to seek a feathered position due to centrifugal force.
Counter Weights
What controls the prop pitch when not in the governing range?
The Beta Valve in conjunction with the PLPS nuts & the prop pitch solenoids.
What is the normal (on speed) range of the primary governor?
1450-1700 RPM
If linkage should fail in the primary governor, where would the spring loaded propellers stabilize?
1700 RPM
he Np shaft drives the governor pump to raise oil pressure from its normal range to a maximum of ___ psi.
375 psi
Oil pressure is always trying to maintain a ___ pitch
Oil pressure is always trying to maintain a low pitch;
conversely the feathering springs and counterweights are trying to send the propeller to feather creating a balancing act of opposing forces.
The overspeed governor maintains what RPM via a factory set screw?
1768 RPM
What is the minimum propeller RPM?
1050RPM
Are there any exceptions to be less than 1050RPM?
While in Feather
How does the primary governor slow the propeller RPM down in an over-speed condition?
The pilot valve raises, allowing oil to drain to case, causing the blade angle to increase (drag) and slows down the propeller.
When the overspeed governor test switch is placed in the test position, it provides ________ power to the N.C. solenoid and opens it allowing ________ to reset the speeder spring tension to ____ - ____ RPM?
Electrical / Oil pressure.
1500-1610
What components feather the propeller?
Centrifugal counterweights and feathering springs
What would be an indication of a primary governor failure during flight?
Propeller above 1700 RPM
How does the fuel topping governor govern propeller speed?
The FTG limits propeller speed by limiting the amount of fuel flowing to the fuel nozzles through a reduction of P3 air pressure in the fuel control unit. This ultimately reduces the power applied to the propeller shaft and thus limits propeller rpm.
What is the governing range of the Fuel Topping Governor?
106% of Selected RPM
95% of Selected RPM in reverse
Which governor reduces fuel flow to the engine to limit propeller RPM?
The Fuel Topping Governor.
What are the two functions of a Fuel Topping Governor?
Limits propeller RPM during stuck/sluggish prop situations & aids during reversing operations.
What do the Fuel Topping Governor and the Primary Governor share with regard to components?
Speeder springs and fly weights.
When is the autofeather armed?
Autofeather switch must be in the armed position
Both power levers must be advanced to approximately 88% N1.
In the event of an engine failure at what percent torque will the opposite autofeather light extinguish?
17%
At what percent torque does the autofeather dump valve open allowing the prop to feater?
10%
What two functions does the synchrophaser perform?
The system automatically matches the RPM of both propellers and positions the propellers at a preset phase relationship in order to reduce cabin noise.
Can the PROP SYNC be used for all operations?
Yes. PROP SYNC is certified for all operations including takeoff and landing.
