UHS Spinners

[Av8r3400]

In that case we used longer prop bolts and added the washers there.

[jrevens]

Yeah, there are all kinds of ways to do it... it's just that being able to add weight to the spinner back plate is so much easier. Test weights are easily & quickly applied using the spinner screws. I should have thought of that, Larry. Applying weights to a skullcap is probably never done... I just got off on a tangent trying to advocate for a bigger spinner with a back plate as far as dynamic balancing is concerned. Self-adhesive weights can be easily adjusted to a tiny fraction of a gram, there are many more possible positions for weight installation and the weight is further from the center of the prop, allowing for a more accurate balance with less/fewer weight(s). However it's done, it'll probably be a big improvement over an unbalanced prop. Like I said, I've balanced hundreds of props - on Lycoming, Continental, Rotax, Jabiru, Subaru, VW, etc., and only once in about 20 years did I find one that was so perfectly balanced that I didn't even touch it after checking - a Quickie II with an O-200 Cont. The out of balance condition is usually substantial and the pilot doesn't even know it.

[Av8r_Sed]

John, follow on question to balancing: Does dynamically balancing a prop on a certified aircraft require an A&P sign off? I'm guessing it does.

[jrevens]

Yes it does, Paul. I've done a few factory built aircraft over the years, when the owner's mechanic was willing to sign it off. I've pretty much done nothing but experimental homebuilts with the builder helping & making his logbook entries.

My story is that I bought the machine at a time in my life when I had a little more money than sense I guess, but it's been great to have. Shortly after I finished my T-18 about 25 years ago a local prop shop offered a "special" price of $250 to our EAA chapter (#43) for a dynamic balance job. They used an old Chadwick Helmuth balancer with the hand-held strobe light, etc. The quality of the job was dependent on the experience & skill of the operator. Long story short, after about 45 minutes, the guy said that was it. The numbers weren't particularily good, but I noticed a good improvement and could see the potential if a really good job was done. The newer technology was becoming available & more affordable, with micro-processors & photoelectric sensors, simplifying & making the whole thing pretty easy. I bought one of the ACES units & have never regretted it. It's a nice compact unit, but the newer ones like Dorsal has are even more compact. I've balanced all kinds of things with mine, including blower wheels, car engine flywheels, etc.

[gizmos]

Thanks guys, just placed my order with kf, all new engine and prop.

[kmach]

Curious what prop combination you decided on ?