Governing, feathering and ground pitch control
A constant-speed propeller varies blade angle to maintain a selected rotational speed within its governing range. It does not keep every engine parameter, aircraft speed or thrust value constant. Start with the selected speed, the actual speed, the available power and whether the system remains within its mechanical and control limits.
Feedback and equilibrium
A conventional hydromechanical governor compares speed-sensitive flyweight force with the selected spring setting. The pilot valve controls the appropriate oil paths. At an on-speed equilibrium, the control mechanism holds the required balance; an overspeed or underspeed produces a correction toward the selected speed. In the usual forward-thrust governing condition, increasing blade angle increases aerodynamic loading and tends to reduce speed, while reducing angle can allow speed to rise.
The oil path is not universal. One design uses oil pressure in a pitch-increasing direction and another in a pitch-decreasing direction. A double-acting system can use hydraulic force for both directions. Springs, counterweights, gas charges and centrifugal twisting moments may provide opposing forces. Identify the actual design before predicting the result of pressure loss or interpreting a valve position. A term such as compact hub does not justify inventing counterweights absent from the stated design.
Feather and reverse are distinct
Feathering places the blades approximately edge-on to the axial airflow to reduce windmilling drag in the relevant installation. The reference matters: a large feather angle relative to the plane of rotation is not the same angle relative to the shaft axis. Stops, latches, accumulators and auxiliary pumps depend on the system. An accumulator can supply stored oil for the defined unfeathering function, but its presence does not prove every restart condition is satisfied.
Reverse pitch produces a retarding effect by changing the direction of the propeller's axial momentum transfer. Do not confuse air accelerated forward with forward propulsive force on the aircraft. Ground pitch control or beta operation uses its defined feedback and lever relationship; its safeguards and permissions come from the actual installation.
Maintenance interpretation
Hunting can arise from instability, control friction, air or contamination, but one symptom does not uniquely identify a failed part. Verify the actual configuration and approved tests before changing a setting. This bank provides no universal feather-check procedure, in-flight reverse permission, governor oil pressure or pressure-loss response. A recognition answer cannot replace the approved maintenance and operating data.