Dynamic Propeller Balancing For Alaska Aircraft

Prop balancing can be very important to the overall health of an airplane. A propeller that’s out of balance causes vibrations, like sound waves, that travel through the airframe. And depending on where those sound waves move, they can cause cracks in various places, such as engine baffling, engine mount, oil cooler, cowlings and induction air box.

The vibration can also affect the moving parts of a plane, such as the alternator, starter or vacuum pump.  It can cause screws to loosen and fall out in various places.  Also, there is the felt vibration that you would feel in your body, which is dependent on where the sound wave comes through the airframe and where you’re sitting.  So perhaps the pilot doesn’t feel the vibration but the passenger does.

Balancing Your Airplane Propeller

Balancing the propeller to the airplane is a fairly simple process.  It involves putting a transducer, which is a vibration sensor, on the engine.  There is an eye that sees the prop and measures the speed/rotation.  A reflective piece of tape is placed on one blade that gives a known point and the dynamic prop balancer shows the heaviest/lightest point on a clock angle.

After setting up the transducer and eye, cables are strung and the engine is run up at normal cruising RPM to see where the corrections need to be made.  Weights are added/removed, the engine is run up again and readings are taken.  The process is repeated until the correct weights have been added/removed and the vibration eliminated. Sometimes it can take several runs to get it dialed in but once you do, it’s noticeably smoother. Many pilots feel a noticeable difference after dynamic propeller balancing.