Hartzell HC-E3YR-7 Owner's Manual page 64

(b) During maneuvering, the propeller operates in Beta
Range (Low Pitch to Full Reverse Pitch) which is
manually selectable. Manual selection of blade
angle by the pilot is accomplished by moving the
pilot control that pushes a Plunger into the Pressure
Control Unit to increase the oil pressure allowed
by the Pressure Control Unit to reach the propeller.
Refer to Figure 2-2. Control of the higher pressure
by the pilot is what allows selection of different
blade angles in Beta Range. Refer to Figure 2-3.
Oil pressures controlled by the pilot will vary
between the minimum oil pressure, that is discussed
in paragraph 1.D.(7)(a), through the maximum
oil pressure of 270 to 300 PSI available from the
governor. Moving toward minimum oil pressure will
obtain positive thrust and moving toward maximum
oil pressure will obtain negative thrust. Refer to
Figure 2-2.
(8) It is recommended that the cockpit mounted lever used by
the pilot to control the pressure control unit be equipped
with a catch or detent that must be consciously disabled to
prevent an unintentional attempt to enter beta range.
(9) Operation in beta range during flight with a fixed wing
aircraft is not permitted. A lighter than air vehicle is
permitted to operate in beta range with no restrictions
since the air vehicle floats and does not fly on an airfoil
and does not stall at a slower forward airspeed.
DESCRIPTION AND OPERATION
Propeller Owner's Manual
136
61-00-36
Page 2-16
Rev. 2 Feb/17