Propeller Governors
What pumps oil into the propeller as well as lets oil drain from the propeller and back to the oil sump?
Propeller governor
What is caused by propellers being out of synchronization?
Oscillations (Vibration and noise)
What is the difference between Anti-icing and De-icing?
Anti-icing: Preventing the formation of ice. De-icing: the removal of ice that has formed on the surface.
What work can an A&P mechanic perform on a governor? What can’t we do?
R/I, inspect condition and OPS, rigging (adjusting high/low stops) CANT: Overhaul, rebuild or major repairs
What are the flyweights purpose in a governor?
L-shaped flyweights, driven by the engine RPM, oppose the force of the speeder spring and allow movement of the pilot valve plunger when required.
The secondary engine will have a synchronizer actuator, the primary will not.
What is the purpose of a slinger ring?
Anti-ice fluid is pumped to the slinger ring and the centrifugal force moves the fluid from the slinger ring across the length of the blade.
Explain how you would check for full travel of propeller governor control cable?
Run the propeller control cable through full travel while someone verifies that the stops at the governor are met prior to the limits reached in the flight deck.
What are the main components of a propeller governor?
Speeder spring, flyweights, pilot valve plunger, spur gear, relief bypass valve
In a synchronization system, the control box needs to compare two signals in order to synchronize the props. How does the control box get these signals?
The magnetic pickups on each propellers governor sense the RPM and send that signal to the control box.
How does current get to the electro-thermal blankets/boots of the propeller blades?
Brushes mounted to the engine contact a slip ring assembly on the spinner bulkhead and transfers current to the boots/blankets on the propeller blades.
Name 3 things to consider when installing a new propeller control cable.
Correct: type of cable, length of cable, routing of cable, rigging of cable.
How does the pilot control the propeller governor?
The pilot cannot directly control the governor nor the blade pitch. When the pilot moves the propeller control lever it sets the compression of the speeder spring in the governor.
Explain how the propeller synchronization system works?
Magnetic pickups are sent to the control box and compared. If the is a difference in RPM then the stepping motor actuator changes the secondary engine RPM until the frequencies match.
What are two ways to determine propeller deice system proper operation?
Check the ammeter for current. Or to check for heat at the boots when the aircraft is on the ground.
What is an accumulator and what is it used for on propellers?
Used to hold pressurized oil and nitrogen to feather or un-feather the propellers by use of the propeller control.
Explain an Underspeed condition in a counterweight propeller.
Explain what happens in the governor that brings it back to an Onspeed condition.
How does the propeller synchrophaser system work?
A pulse generator is keyed the master prop blade, producing a pulse when its at its reference point. Pulses sent to control box and compared and adjusted so props are the same phase. While still comparing and adjusting RPM of the secondary engine to the primary engine.
What cause the prop deice ammeter to pulse?
Once energized the prop deice timer sends current to each blade in turn (each blade for a few seconds each)
Explain propeller blade pitch, propeller control position and engine RPM when in takeoff configuration and cruise configuration.
Takeoff Configuration: Prop control is in the full FWD position, blades low pitch/high RPM
Cruise Configuration: Prop control is in full AFT position, blades high pitch/low RPM