Mooney M20V - Page 488

MOONEY INTERNATIONAL CORPORATION
M20V SERVICE AND MAINTENANCE MANUAL
Date
MAR 2017
Rev Date
Page
10
61-20-90 - PROPELLER TROUBLESHOOTING
(Refer to Hartzell Owner’s Manual 115N for detailed Troubleshooting Instructions)
TROUBLE SYMPTOM POSSIBLE CAUSE/REMEDY
Hunting and Surging:
Hunting is characterized by a cyclic
variation in engine speed above and
below desired speed.
Licensed repair facility should check:
1 - Governor
2 - Fuel control
Surging is characterized by a large
increase/decrease in engine speed,
followed by a return to set speed af-
ter one or two occurrences.
NOTE
Air trapped in the propeller hy-
draulic system will cause the
pitch control to be imprecise and
may result in propeller surging.
1 - Perform engine start and warm-
up per the Pilot’s Operating Hand-
book (POH).
2 - Cycle the propeller control
throughout its operating range from
low to high (or as directed by the
POH).
3 - Repeat this procedure at least
three times to purge air from the pro-
peller hydraulic system and to
introduce warmed oil to the cylinder.
NOTE
Pitch change response on the
first operation from low to high
bladepitchmaybeslow,but
should speed up on the second
and third cycles
4 - Verify proper operation from low
pitch to high pitch and throughout
operating range.
5 - Shut down the engine in accor-
dance with the POH.
Engine Speed Varies with Airspeed:
Increase in engine speed while de-
scending or increasing airspeed.
1 - Governor is not increasing oil
volume in the propeller.
2 - Engine transfer bearing is leak-
ing excessively.
3 - Excessive friction in blade bear-
ings or pitch changing mechanism
Decrease in engine speed while in-
creasing airspeed.
Governor pilot valve is stuck and is
excessively increasing oil volume.
Increase in engine speed while de-
creasing airspeed.
Governor pilot valve is stuck and is
excessively decreasing oil volume.
Decrease in engine speed while de-
creasing airspeed.
1 - Governor is not reducing oil vol-
ume in propeller.
2 - Excessive friction in blade bear-
ings or pitch changing mechanism.
61-20-90