Propeller Owner's Manual
136
TESTING AND TROUBLESHOOTING
61-00-36
Page 4-11
Rev. 2 Feb/17
(7) Engine oil transfer system is leaking excessively.
(a) Normal governor oil pumping capacity is unable to
overcome the excessive leakage to decrease blade
pitch.
(8) Oil volume is not increasing in the propeller to decrease
blade pitch because of the pressure control unit.
(a) The plunger stop screw (refer to Figure 2-2,
Figure 3-14, or Figure 3-15) is incorrectly
adjusted/positioned to obtain the correct Position 3
oil pressure (refer to Figure 3-16). Oil pressure will
be lower than required.
F. Propeller Overspeed
(1) Check for tachometer error.
(2) Check propeller low pitch adjustment if the overspeed is
during engine run-up with the aircraft static.
(3) Governor maximum RPM set too high.
(4) Excessive friction in propeller blade bearings or pitch
change mechanism is not permitting a increase of
blade pitch.
(5) Governor is not decreasing oil volume in the propeller to
increase blade pitch.
(a) Blockage of the oil line from the governor to the
propeller.
(b) Governor pilot valve is sticking to retard oil drain.
(6) A sudden increase of propeller/engine RPM with an
increase of engine power followed by an equally sudden
RPM stabilization at Max RPM. A forward surge may be
felt also.
(a) The plunger stop screw (refer to Figure 2-2,
Figure 3-14, or Figure 3-15) is incorrectly
adjusted/positioned to obtain the correct Position 3
oil pressure (refer to Figure 3-16). Oil pressure will
be higher than required. Blade pitch movement into
beta range may be occurring during underspeed
operation below 900 RPM.
