Page 2-9
Dec/05
DESCRIPTION AND OPERATION
61-00-75
Propeller Owner's Manual
175
A. Constant Speed, Counterweighted, Nonfeathering Propellers
Propeller models HC-82(X,V)(F,K,L)-1( )( ) and
HC-83(X,V)20-1( )( ). Refer to Figure 2-6.
Constant speed 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.
A counterweight is a weight that is attached to each blade
clamp to cause the blade to rotate to a higher blade pitch.
Counterweighted propellers require governor supplied
oil to decrease blade pitch. If the oil supply is lost, the
counterweighted propeller will go to high pitch, or low 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 condition and blade design.
This force is generally very small in relation to the other
forces.
Propeller forces consisting of blade counterweight centrifugal
twisting moment 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 higher blade angle. A
variable hydraulic force (oil under pressure from the engine
driven governor) toward a lower 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.
OBSOLETE PROPELLER MODELS. SEE COVER PAGE
WARNINGS AND SERVICE BULLETIN HC-SB-61-331