Check propeller blade tracking frequently.  Blade track is the ability of one blade to follow the other in the same plane of rotation.  If your propeller has been bumped or compromised, check the tracking.  A change in tracking can be unnoticeable or cause severe vibrations.  Improper tracking will cause the propeller to feel out of balance but the cure is distinct from balancing.  While your A&P mechanic can check the propeller tracking, once discovering your propeller is out of track, a Professional Propeller Technician must realign it for you.  Always have the blade track checked after the hub bolts are tightened. 

Every propeller is statically balanced at the factory.  If the propeller-engine combination feels rough in flight, ask your mechanic to remove the propeller, rotate it 180 degrees on the engine crankshaft flange, and re-install.  Again check blade track.  This provides a means to verify that the crankshaft flange is true. 

To check blade track, place a smooth board just under the tip of the lower blade.  On controllable props, move the tip fore and aft carefully through its small range of motion, making small pencil marks at each position.  Center the blade between these marks and draw a line the full width of the blade.  Repeat this procedure with another blade tip.  The lines should be separated by not more than 1/16 inch.  Differences greater than 1/16 inch may be an indication of bent blades, improper installation or foreign particles between the hub and crankshaft mounting faces.  

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