Hartzell HC-E4 3 Series - Loss of Propeller Control; Failure to Feather (or Feathers Slowly); Failure to Unfeather

Propeller Owner’s Manual
147
TESTING AND TROUBLESHOOTING
61-00-47
Page 4-6
Rev. 6 May/20
C. Loss of Propeller Control
(1) Propeller goes to uncommanded high pitch (or feather).
(a) Loss of propeller oil pressure - check:
1 Governor pressure relief valve.
2 Governor drive.
3 Engine oil supply.
(b) Start lock not engaging.
(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) Broken feathering spring.
(4) RPM control sluggish (especially on reducing RPM)
(a) Broken feathering spring.
D. Failure to Feather (or feathers slowly) (Rev. 1)
(1) Broken feathering spring (if applicable).
(2) Check for proper function and rigging of propeller/governor
control linkage.
(3) Check the governor function.
(4) The propeller must be inspected for misadjustment or
internal corrosion (usually in blade bearings or pitch
changing mechanism) that results in excessive friction.
(a) This inspection must be performed by a certied
propeller repair station with the appropriate rating.
E. Failure to Unfeather (Rev. 1)
(1) Check for proper function and rigging of propeller control
linkage.
(2) Check the governor function.
(3) The propeller must be inspected for misadjustment or
internal corrosion (usually in blade bearings or pitch
change mechanism) that results in excessive friction.
(a) This inspection must be accomplished by a certied
propeller repair station with the appropriate rating.