Originally Posted by
av-mech
I highly suggest that you find someone with either a MicroVib II or ACES system and have your rotating mass balanced. The rotating mass consists of the crank, prop, spinner and anything else connected to that which spins. I do prop balancing several times a month at my shop on all kinds of aircraft and I can tell you that it will make a big difference in most cases. The A&P/engineer that does the balancing should be able to work you down to a value of at least .030" ips (inches per second). Values lower than that are possible but as you get closer to zero the need for accurate placement and the amount of weight needed goes up exponentially. If you get a lower value great, but don't let them spend to much time as it just ends up being not worth the time invested. Weight will be added to your spinner screws during several runs. When the value is as low as the operator can get it, he will move that weight combo from the outer screws to the spinner backplate. He should check it after moving to assure that the value did not change to much.
Broken crankshafts, cracked oil coolers/baffling/brackets/exhaust etc....are many times attributable to a poor distribution of mass about the centerline of the crankshaft. Prop balancing will go a long way to improving this issue.
Remember, with a wooden prop always leave the aircraft with the prop in a horizontal position. If left vertical, moisture will tend to migrate towards the bottom blade and can significantly effect your balance.
Arnold Holmes
AV-Mech LLC
EAA 519850