What is the purpose of counterweights on a propeller?

Variable pitch propellers have either counterweights or a lock to limit unwanted blade angle movement to low pitch after failures. Counterweights are attached to the blade at a position that will cause the centrifugal loads on the counterweights to drive the blades towards higher pitch (towards feather).

How do counterweight propellers increase blade angle?

The hydraulic counterweight propeller consists of a hub assembly, blade assembly, cylinder assembly, and counterweight assembly. The counterweight assembly on the propeller is attached to the blades and moves with them. The centrifugal forces obtained from rotating counterweights move the blades to high angle setting.

What do the flyweights do in the prop governor?

Flyweight force exceeds governor spring force, lifting the pilot valve and allowing high-pressure oil to enter the propeller. This increases the propeller pitch and brings the engine rpm back to the selected value. As engine and governor rpm decrease the governor returns to the ON SPEED condition.

How does a prop governor work?

The propeller governor is responsible for telling the propeller what to do by moving pressurized oil back and forth through the propeller shaft. The oil is directed to the propeller where it pushes a piston to alter the pitch of the blades.

Why do we need to synchronize the propellers?

Propeller synchronization serves mainly to increase the comfort of crew and passengers, since its primary purpose is to reduce the “beats” generated by propellers that are turning at slightly different speeds. These beats can become very irritating to persons inside the aircraft after a time.

PROPELLER COUNTER WEIGHTS - Constant Speed Props

When should I turn on my prop sync?

The prop sync should always be off for takeoff, landing, and single-engine operation. The AFM/POH should be consulted for system description and limitations. A variation on the propeller synchronizer is the propeller synchrophaser.

What is synchronizing and Synchrophasing?

Synchrophasing allows the pilot to adjust the phase angle between the propeller on the various engines to reduce the noise and keep vibration to a minimum.

What happens when a prop governor fails?

Governor Failure

If a governor is not doing its job and a propeller over- speeds, the amount of overspeed is controlled by two things: engine power output and airspeed. Reducing throttle and airspeed will minimize the amount of over- speed.

How does the governor change the propeller pitch?

To maintain a constant speed, the governor senses the decrease in speed and increases oil flow to the propeller, moving the blades to a lower pitch and allowing them to maintain the same speed.

What causes propeller overspeed?

In propeller aircraft, an overspeed will occur if the propeller, usually connected directly to the engine, is forced to turn too fast by high-speed airflow while the aircraft is in a dive, moves to a flat blade pitch in cruising flight due to a governor failure or feathering failure, or becomes decoupled from the ...

How do flyweights work?

The "L" shaped flyweights, which spin around in a circle, are connected to the engine through gears. They're also connected to the pilot valve, which they move up and down. When the engine speeds up, the weights spin faster and fly out due to centrifugal force, lifting the pilot valve up.

What is feathering a propeller?

On many variable pitch propellers, the blade pitch can be increased to the point that the chord line of the blade is approximately parallel to the on-coming airflow. This process is referred to as feathering.

What is the purpose of a governor balance spring?

A mechanical governor uses flyweights to create a force based off of crankshaft speed which is balanced by the force of the governor spring. The top engine speed is varied by increasing the spring force to run faster or decreasing the force to run slower.

What causes mechanical vibration in a propeller?

Causes of vibration: propeller

Vibration originating from the propeller is usually caused by a mass imbalance. A mass imbalance is when the center of gravity of the propeller is not in the same location as the center of rotation of the propeller.

Why is a constant speed counterweight propeller normally placed in high pitch position before the engine is stopped?

Why is a constant-speed counterweight propeller normally placed in full HIGH PITCH position before the engine is stopped? To prevent exposure and corrosion of the pitch changing mechanism. The engine will turn at its rated takeoff RPM at sea level when the throttle is opened to allowable takeoff manifold pressure.

What force causes a greatest stress on a propeller?

These are centrifugal force, thrust bending force, torque bending force, aerodynamic twisting moment, and centrifugal twisting moment. Of them all, centrifugal force causes the greatest stress on propellers. This is the force that tends to pull the blades from the propeller hub.

How do you control the pitch on a propeller?

In other words, you are able to control the pitch of the entire propeller, by changing the orientation of the root section on the hub. This is done by the means of a hydraulic cylinder. When the required orientation or pitch of the propeller is obtained, the blades are locked in that position.

How do you fix a overspeed propeller?

Propeller overspeeds can usually be brought under control with a power reduction. A propeller imbalance resulting from asymmetric ice shedding might be fixed with a propeller rpm change, which changes the angle of attack of the prop blades and tends to break off ice that has formed. to tear the engine off its mounts.

What is meant when a propeller governor is in an on speed condition?

Pilot valve closes propeller line to maintain pitch. A condition of a propeller governor system in which the engine is turning at the speed selected by the governor. The centrifugal forces acting on the governor are exactly balanced by the compression or speeder ring.

What is the purpose of incorporating a Synchrophasing system on a turboprop engine?

Propeller synchrophasing is an effective way of reducing interior noise and vibration of turboprop-driven aircraft.

What is Synchrophasing system?

A system that controls both the rotational speed AND relative phase between left and right propeller blades is a synchrophasing system. As propellers rotate, there are both non-preferred and optimum phase relationships between left and right propellers.

What is propeller imbalance?

Propeller unbalance, which is a source of vibration in an aircraft, may be either static or dynamic. Propeller static imbalance occurs when the center of gravity (CG) of the propeller does not coincide with the axis of rotation.

Why is the tip of the propeller not covered by ice protection?

Generally, ice collects asymmetrically on a propeller blade and produces propeller unbalance and destructive vibration and increases the weight of the blades.