Nice Air Operation Procedure PA-34 Seneca
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down due to increasing drag on the blade. However, blade angle is decreased automatically to reduce
the drag to maintain the RPM constant.
When the airplane drops it’s nose, it start to descend. As it descend, airspeed will increase. The RPM
is also increased due to decreasing drag on the blade. However, blade angle is increased automatically
to increase the drag to maintain the RPM constant.
Where is the governor located?
In front of the engine.
What does governor do?
The fly weight inside the governor senses the change in RPM by sensing the change in centrifugal
force. It opens the pilot valve. When the RPM increase, the valve opens the line without the pump. It
drains the oil back from propeller hub to increase the blade angle. When the RPM decrease, the valve
opens the line with the pump. The pump send the oil to propeller hub to decrease the blade angle.
What makes it high pitch?
Nitrogen charged in the hub and counter weight at the root of the propeller blades.
What makes it low pitch?
High pressure of the oil and aerodynamic force on the prop.
What does pilot do when he move the prop lever in the cockpit? What will happen to governor?
It change the tension of the speeder spring. High tension requires more centrifugal force on the fly
weight. It increase the RPM. Low tension requires less centrifugal force on the fly weight. It decrease
the RPM.
Where is the oil from?
Engine oil reservoir at the bottom of the engine.
What will happen if you lose engine oil completely?
It become high pitch. Moves toward feathering.
How can you feather manually?
Move the propeller lever all the way down to the feather detent.
What is the purpose of feathering?
To reduce the drag caused by windmilling. To avoid further damage to the engine.
What force makes it feather?
Nitrogen charged in the hub and counter weight at the root of the propeller blades.
How can you unfeather the prop?
Use starter.
How does the unfeatering accumulator work?(if it is equipped)
It has diaphragm inside. Nitrogen is charged in one side. Engine oil is pumped in on the other side
from the governor during normal operation. When the propeller lever is moved down to feather posi-
tion, the valve is closed to keep high oil pressure inside the accumulator(300PSI). When the prop lever
is moved to high RPM position, the valve is opened and the nitrogen push the oil back. The oil is sent
to the hub through the governor and crankshaft to decrease blade angle. Once the blade angle changes,
the wind pick up the prop to start windmill. In this way, the engine can be restarted without stress on
the cylinders(N43130 does not have unfeathering accumlator).
Will the prop feather when you shut down the engine after landing? Can you feather the prop when engine is not