EN-1320
OPERATION AND INSTALLATION MANUAL
When the engine condition lever is moved, the outer valve is turned and oil channels are opened.
Pressurized oil flows either through low pitch channel or through high pitch channel into the propeller (figure
12-2B).
When the propeller reaches required position, the channels are again closed by moving of beta-ring
feedback (figure 12-2C).
D. Feathering
If an engine failure occurs during flight, it is necessary to feather the propeller. Twin engine aircraft are
usually equipped with a feathering system consisting of a feathering valve and feathering pump.
The
system is initialized by a cockpit button or automatically.
a) Manual Feathering
Pilot activates by pushing appropriate cockpit button the feathering pump and feathering valve. Now
oil from the feathering is connected directly to the high pitch channel and propeller moves to feather.
This action is indicated by feathering lamp in the cockpit. After engine restart and idle setting, the
propeller moves out from feather position.
b) Automatic feathering
Action is similar to manual feathering only the activation is automatic based on engine torque evaluation.
Usually the automatic system is limited to some engine condition lever range. Automatic feathering is
indicated by a lamp in the cockpit, the circuit can be switched off.
c) Emergency Feathering
It is used when the feathering pump is out of operation or it is not installed. Emergency feathering is
activated by moving the propeller condition lever onto feather stop. Blades are forced into feather position
by counterweights moment and eventually by oil pressure. Feathering time is about three times longer than
manual and automatic feathering. Emergency feathering can be used at engine stop.
Figure 12-2 Governor function in beta mode of operation
61-10-20
PROPELLER CONTROL SYSTEM
(
Installation With Jihostroj LUN-Series Governor)
Page 12-3
2017-10-06
