Hartzell HC-D2MV20-3 Series Owner's Manual And Logbook page 53

C. Propeller Models HC-D2(MV,V)20-7( )
HC-D2(MV,V)20- 8( ). Refer to Figure 2-4.
(1) These propeller models may be controlled either manually
or by a governor and are always non-reversing. If
governing, the basic components consist of a propeller, a
hydraulic unit, a valve assembly, a governor, and a T-drive
unit. If manual control is used, the basic components
consist of a propeller, a hydraulic unit, and a valve
assembly.
(2) This propeller model series is capable of approximately
14 degrees of blade angle range and uses a diaphragm to
seal between the piston and the cylinder.
(3) On HC-D2(MV,V)20-7( ) models the hydraulic unit is
designed so the cylinder of the hydraulic unit will attach
to Continental E-185 and E-225 engines that use four
attachment points. This requires 4 holes in the cylinder to
receive 4 socket head cap screws that are threaded into
the engine.
(4) On HC-D2(MV,V)20-8( ) models the hydraulic unit is
designed so the cylinder will attach to a Lycoming O-435
engine with an SAE 20 splined thrust plate that uses six
attachment points. This requires six holes in the cylinder
to receive six studs from the engine and is secured in
place with one nut on each stud.
DESCRIPTION AND OPERATION
Propeller Owner's Manual
140
61-00-40
and
Page 2-13
Rev. 2 Jun/12