Thrush Aircraft S2R-T660, Maintenance Manual

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THRUSH AIRCRAFT INC - T660 TURBO THRUSH
AIRCRAFT MAINTENANCE MANUAL
PROPELLER SPEED SELECT AND FEATHERING CONTROL
The cockpit propeller lever has two functions:
A. The first function is to select the propeller RPM in takeoff, climb, and cruise configurations.
B. The second function is to feather the propeller when it is required.
The cockpit propeller lever is connected to the speed select lever on the CSU.
The first function is performed by varying the speeder spring pressure by rotating the propeller
speed select lever (Fig. 4-2, #9) toward the propeller speed max stop (Fig. 4-2, #10). The second
function is performed by rotating the propeller speed select lever (Fig. 4-2, #9) toward the feathering
stop. This action will cause the override rod to pull the pilot valve plunger upward, therefore allowing
servo oil to be dumped from the propeller servo piston. This action will cause the propeller blades to
travel to the feather position, by action of the feather-return spring pressure acting on the propeller
servo piston.
PROPELLER SETTINGS
A. Maximum RPM . . . 1,700 RPM
B. Cruise Power . . . Approxi35
°
@ 42 in. station
C. Full Feathered Angle . . . 88.5+ 0.5
°
@ 42 in. station
D. Mechanical Reverse Pitch Stop . . . -11
°
+ 0.5
°
@ 42 in. station
E. Angle at which servo piston just touches the three low pitch stop rod beta nuts (which
move the propeller beta feedback ring) is 10.0
°
+ .1
°
when blades are held toward decrease
position at the 42 inch station. The hydro-mechanical low pitch stop occurs at a blade angle
of approximately 11
°
when the propeller dome has traveled sufficiently to fully close the
beta valve and shut off the oil flow to the propeller.
The specific low-pitch blade-angle determined through aircraft flight and ground test, during
which the controllability of the aircraft is checked, is approximately 11
°
for the Hartzell
propeller installed on the Turbo Thrush.
The way to set the specific low-pitch blade-angle is to adjust the hydraulic low pitch stop.
This is accomplished by proper adjustment of the three beta nuts, by using the 1600-RPM
Np Torque Setting Chart (Figure 4-5).
Effective: 12/17/03
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