Page 2-13
Dec/05
DESCRIPTION AND OPERATION
61-00-75
Propeller Owner's Manual
175
B. Constant Speed, Non-counterweighted, Nonfeathering
Propellers
Propeller models HC-82(X,V)(F,L)-6( )( ). Refer to Figure 2-6.
Constant speed, non-counterweighted, nonfeathering
propellers are typically used on single engine aircraft.
Propeller blade angle change is actuated by a hydraulic
piston/cylinder combination mounted on the forward end of
the propeller hub. The linear motion of the hydraulic piston
is transmitted to each blade through a sliding rod and fork
system, connected to a blade clamp that rotates with the
blade. Each blade is retained on the propeller hub by a blade
clamp and thrust bearing. The thrust bearing permits the
blade to change angle with the blade under centrifugal load.
Propeller forces consisting of centrifugal and aerodynamic
twisting moment of the blades in various combinations are
constantly present while the propeller is operating. The
summation of these forces causes the propeller to rotate
to a lower blade angle. A variable hydraulic force (oil under
pressure from the engine driven governor) toward a higher
blade angle opposes the summation of these forces. Oil is
metered by the governor to oppose these constant forces
and maintain a constant engine RPM.
A non-counterweighted propeller requires governor supplied
oil to increase blade angle. If the oil supply is lost, the non-
counterweighted propeller will go to low pitch, or high RPM.
The weight of each propeller blade when spinning, generates
centrifugal force and a twisting force that attempts to rotate
each blade to a lower blade angle.
Air flow around the blade generates lift and an aerodynamic
twisting moment that will attempt to increase or decrease
blade angle, depending on flight conditions and blade
design. This force is generally very small in relation to the
other forces.
A governor is an engine speed-sensing device that maintains
a constant engine/propeller RPM by changing blade angle
and varying load on the engine.
OBSOLETE PROPELLER MODELS. SEE COVER PAGE
WARNINGS AND SERVICE BULLETIN HC-SB-61-331