Hartzell HC-D2MV20-3 Series Owner's Manual And Logbook page 55

D. Propeller Model HC-D3MV20-8D. Refer to Figure 2-5.
(1) This propeller model uses manual control and is non-
reversing. The basic components of this propeller
assembly consist of a propeller, hydraulic unit, and 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) The hydraulic unit is designed so the cylinder will attach
to the engine with an SAE 20 splined thrust plate using
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
Page 2-15
Nov/02