TESTING AND TROUBLESHOOTING
61-00-15
Page 4-8
Rev. 24 Dec/20
Propeller Owner's Manual
115N
D. Loss of Propeller Control (-2, -4 or -5 propellers)
(1) Propeller goes to uncommanded High Pitch (or Feather)
(a) Loss of propeller oil pressure - Check:
1 Governor pressure relief valve for proper
operation
2 Governor drive for damage
3 Adequate engine oil supply
4 Engine transfer bearing leaking excessively
(b) Start locks not engaging (-2 and some -5 feathering
propellers only)
(c) Air charge pressure too high (-2, -5). Refer to Air
Charge in the Maintenance Practices chapter of this
manual.
(2) Propeller goes to uncommanded Low Pitch (High RPM)
(a) Governor pilot valve sticking
(3) RPM Increases with Power and Airspeed, Propeller RPM
Control has Little or No Effect
(a) Excessive friction in blade bearings or pitch
changing mechanism.
(b) Air charge lost or low. (-2, -5). Refer to the Air
Charge section in the Maintenance Practices
chapter of this manual.
(c) Broken feathering spring (-2, -5).
(4) RPM Control Sluggish
(a) Air charge lost or low (-2, -5). Refer to the Air Charge
section in the Maintenance Practices chapter of this
manual.
