take final blade measurements and record on each blade’s  inspection record. Balance and match the propeller blades and  anodize and paint them for long-term corrosion protection. Small variances in engine speed are normal and are no cause  for concern. An increase in engine speed while descending or  increasing airspeed with a nonfeathering propeller could be. When both the hubs and the blades have completed the  overhaul process, the propeller is ready for final assembly.  Recheck part numbers with the manufacturer’s specifications.  Lubricate and install the parts per each unit’s particular  overhaul manual. After final assembly, check both high-  and low-pitch blade angles on constant-speed propellers  for proper operation and leaks by cycling the propeller with  air pressure through its blade angle range. Then, check the  assembled propeller for static balance. If necessary, place  weights on the hub areas of each “light” blade socket to  bring about its proper balance. These weights should be  considered part of the basic hub assembly and should not be  moved during subsequent dynamic balancing to the engine. As with most aircraft components, all of the hardware on  the propeller assembly must be safety wired, unless secured  by self-locking devices. Then, the final inspector fills out  and signs maintenance release tags reflecting the work  accomplished, applicable ADs, and all incorporated service  documents. These documents certify that the major repairs  and/or alterations that have been made meet established  standards and that the propeller is approved for return to  service. All minor repairs and minor alterations on propellers  must be accomplished by a certified repair station, an airframe  and powerplant technician (A&P), or a person working under  the direct supervision of such a technician or an appropriately  rated air carrier. Major repairs or alterations, including the  overhaul of controllable pitch propellers, must be done by an  appropriately rated repair station, manufacturer, or air carrier.  Some brief examples of troubleshooting problems and  possible causes are provided in the following subsections.  Always refer to the correct manual for actual information  on troubleshooting. Hunting is characterized by a cyclic variation in engine speed  above and below desired speed. Surging is characterized  by a large increase/decrease in engine speed, followed by a  return to set speed after one or two occurrences. If propeller is  hunting, an appropriately licensed repair facility should check: Turboprop engines are used for many single, twin, and  commuter aircraft.  [Figure 7-43]  Smaller turboprop engines,  such as the PT-6, are used on single and twin engine designs;  the power ranges from 500 to 2,000 shaft horsepower.  [Figure 7-44]  Large commuter aircraft use turboprop engines,  such as the P&W 150 and AE2100 that can deliver up to  5,000 shaft horsepower to power mid-sized to large turboprop  aircraft.  [Figure 7-45]  The turboprop propeller is operated  by a gas turbine engine through a reduction-gear assembly.  It has proved to be an extremely efficient power source.  The combination of propeller, reduction-gear assembly, and  turbine engine is referred to as a turboprop powerplant. 7-30 Figure 7-43.  Turboprop commuter.  Engine Speed Varies with Flight Attitude (Airspeed) Prop Reassembly Failure to Feather or Feathers Slowly  Hunting and Surging Troubleshooting Propellers  3.  Synchrophaser or synchronizer. 2.  Fuel control, and 1. Governor, 4.  Check the propeller for misadjustment or internal  corrosion (usually in blade bearings or pitch change  mechanism) that results in excessive friction. This  must be performed at an appropriately licensed  propeller repair facility. Turboprop Engines and Propeller Control  Systems 3.  Check the governor drain function. 2.  Check for proper function and rigging of propeller/  governor control linkage. 1.  Refer to the air charge section in the maintenance  manual if the air charge is lost or low. C.  Excessive friction in blade bearings or pitch changing  mechanism. B.  Engine transfer bearing leaking excessively. A. The governor not increasing oil volume in the  propeller. Failure to feather or slow feathering of the propeller requires  the FAA-certificated A&P technician to: