Page 2-31
Dec/05
DESCRIPTION AND OPERATION
61-00-75
Propeller Owner's Manual
175
(5) Refer to Figure 2-14. This figure illustrates a feathering
propeller governor. This governor is similar to the
constant speed governors illustrated in Figures 2-11
through 2-13, with the addition of the lift rod. When it
is desired to feather the propeller, the lift rod may be
moved by the cockpit control to mechanically engage the
pilot valve to lift the valve. The lifted pilot valve dumps oil
to increase propeller pitch until the propeller feathers.
(6) Refer to Figure 2-15. This figure illustrates a governor
as a component of a synchronizing or synchrophasing
system. A synchronizing system is employed in a multi-
engine aircraft to keep the engines operating at the
same RPM. A synchrophasing system not only keeps
RPM of the engines consistent, but also keeps the
propeller blades operating in phase with each other.
Both synchronizing and synchrophasing systems serve
to reduce noise and vibration.
(7) A Hartzell synchronizing or synchrophasing system
uses one engine (the master engine) as an RPM and
phase reference and adjusts the RPM of the remaining
engine(s) (slave engine[s]) to match it. The RPM of
the master engine is monitored electronically, and this
information is used to adjust the voltage applied to the
electrical coil on the slave governor(s). The voltage to
the coil either raises or lowers a rod, which changes
the force on the speeder spring. In this manner, engine
RPM and phase of the propellers is synchronized or
synchrophased.
OBSOLETE PROPELLER MODELS. SEE COVER PAGE
WARNINGS AND SERVICE BULLETIN HC-SB-61-331
