Propeller Owner's Manual
136
DESCRIPTION AND OPERATION
61-00-36
Page 2-12
Rev. 2 Feb/17
D. Propeller Beta (Reverse) Operation - Refer to Figure 2-2 and
Figure 2-3
(1) Propeller beta operation is in the range between low pitch
and maximum reverse pitch. Blade pitch or blade angle
is controlled manually by the pilot through a lever/cable
connected to a plunger in the pressure control unit; thus,
blade angle control in beta range is not controlled by the
RPM sensing hardware of the governor and constant
speed operation is not maintained in beta range. RPM will
change as blade angle is changed. Blade angle control of
the propeller by the governor is disabled and is manually
controlled by the pilot.
(2) Constant speed propellers that do not reverse will operate
between a high pitch and a low pitch range under governor
blade pitch control for constant speed operation. In these
propellers low pitch is maintained with a fixed stop and will
not permit blade angle movement below low pitch.
(3) A propeller with reversing capability must be able to reach
blade pitch below low pitch in the beta range (between low
pitch and maximum reverse pitch). Maximum reverse pitch
is maintained by a fixed stop.
(4) The low pitch stop on a reversing propeller must function
as a stop when in constant speed operation (governor
control), but it must permit blade pitch movement below
low pitch into the beta range when amphibian water
maneuvering or lighter than air vehicle maneuvering is
desired. Beta range permits manual selection of a low
positive blade pitch for variable low positive thrust and
selectable reverse blade pitch for variable reverse thrust.
The solution to the requirement of a fixed low pitch stop
for constant speed operation and releasable to permit
movement into beta range operation is the beta lockout
assembly shown in Figure 2-2. This unit is held in place
between a preloaded reversing spring and a retaining
ring that is anchored in the barrel of the hub, as shown in
Figure 2-2.
