Hartzell HC-D2MV20-3 Series Owner's Manual And Logbook page 49

2. Propeller Description
A. Propeller Model HC-D2(MV,V)20-3( ). Refer to Figure 2-2.
(1) This propeller model uses manual control and is reversing.
The basic components of this propeller assembly consist
of a propeller, a hydraulic unit, and a valve assembly.
(2) A blade angle range up to 33 degrees enables reverse
thrust operation for ground or water handling.
(3) The hydraulic unit is designed so the cylinder will attach
to the 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
Page 2-9
Rev. 2 Jun/12