Ungoverned Propellers

The following is derived from maintenance facility submissions to the FAA's Service Difficulty Reports database


Beech 300 King Air

No Unfeather Ability

During engine pre-takeoff performance runs, the #2 prop would not come out of feather. Maintenance inspected the engine and performed engine runs but could not duplicate the discrepancy. Out of caution, the right engine prop governor was replaced.

Part total time: 4957.0 hours

Cessna 182K Skylane


Pilot reported engine rpm went from 2500 down to 1700 in cruise. The engine continued to operate smoothly and produce power. The pilot returned to the airport under power and made a normal landing. During the static engine run up, the engine produced 26 inches of manifold pressure but only 1400 rpm. After replacing the propeller governor, the aircraft operated normally.

Part total time: Unknown

Cessna 208B Grand Caravan

Abnormal Beta Range Exit

After landing, the pilot pulled the power control aft into beta range to slow his taxi speed. When bringing the control back into forward range, the pilot noted an abnormal amount of force required to come over the beta reverse gate. This was attempted three times with the same results. Aircraft was shut down. Rigging was inspected but no problems were evident. The prop governor was replaced with an overhauled unit. Rigging was checked after installation and the aircraft was tested and placed into beta numerous times without binding or abnormal force required to move the control in either direction over the gate.

Part total time: 3944.0 hours

Cessna 402C Utililiner

Right Propeller Overspeed

Pilot reported a right propeller overspeed indication on climb out, then difficulty controlling the propeller at a steady rpm afterward. Removed and replaced the right propeller governor, operational and leak-checks were good with no further defects.

Part total time: 8266.0 hours

Mooney M20J 201

Pump Cavity Internal Damage 

The governor was bench-checked and found not to be achieving rpm above 1600. Pressure relief was low. Customer requested o/h of the governor, which was disassembled and found to have internal damage of the pump cavity. Damage from an unknown source rendered the governor beyond economical repair. Reason for low rpm is unknown.

Part total time: 1596.0 hours Θ


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