Finally, balancing the propellor

With the paint on and my local mechanic finally harassed enough to squeeze me into his busy schedule, it was propellor balancing day! I took a quick flight to warm everything up and then removed the cowling. After John got his equipment setup we made the first run to see how far off it would be, I was a bit nervous but it came at 0.26 ips which was in the typical range of 0.20 to 0.30 ips.

Adding two washers to the outside of the spinner got our second run down to 0.10 ips. Next was a more permanent mounting, unfortunately my ring gear did not have a bunch of holes, like most do, which meant attaching the permanent weight to the spinner bulkhead. With some good fortune John noticed holes in the propellor hub lined up with where the weight was needed so no holes in the bulkhead would be needed (eliminating the risk of future cracks forming). With washers in place and the screws safety wired the next run came in at 0.15 ips, we expected it to be worse since the weight was moved closer to the center of the propellor.

The only pain was that the spinner had to be removed for each adjustment (removal and installation of about 20 screws) but on subsequent runs we had 0.07 ips followed by 0.04 ips. I’ve read the goal is less than 0.08 and that 0.02 – 0.04 ips is considered ideal. At the top end of the ideal range we called it good and buttoned everything up. On my test flight I could feel a difference and now will sleep better knowing that the prop won’t be abusing the engine going forward. All told it took a couple hours, not bad.

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