The pitot tube on the RV-12 goes through the hollow propeller shaft and protrudes out the front of the spinner. The tube itself is stationary while the prop and spinner turn around it. This somewhat unusual arrangement was done to accommodate easy wing removal, making it unnecessary to disconnect the tubing for the Pitot each time the wings are removed.
The thought behind the removable wings was that people could save money by storing the airplane at home and trailering it to the airport, avoiding the cost of a hangar. I may have heard of one person who actually tried this while everyone else keeps the airplane at an airport in the usual fashion.
The Pitot tube as supplied has male threads on one end and is threaded into a rigid nylon block which is bolted to existing threaded holes in the gearbox housing. If all the flat surfaces on the nylon block were at right angles to each other the forward end of the Pitot would be perfectly centered in the hole through the propeller hub.
As can be clearly seen in the second pic, it's way off. I took everything apart and cleaned all the mating surfaces with no effect. Somewhere a surface wasn't square with its neighbors.
through a hole with bushing in the forward tip of the prop spinner. Left like this, a constant radial load would be applied to the bushing, no doubt contributing to wear as some builders have documented on the forums. I explained all this to the Mothership and was told it's fine. Let the bushing handle it.
A few measurements and calculations showed that placing a 0.008 inch shim between the upper forward surface of the nylon block and the mating machined surface on the gearbox housing would bring everything into alignment. The pic at left shows what that might look like if it were done. If I were building Experimental-Amateur Build (E-AB) rather than Experimental Light Sport (E-LSA) I could do this sort of thing. Since I am E-LSA I must build my airplane exactly like the ASTM Conforming Prototype, at least until I get my airworthiness certificate. Then, oddly, I can do pretty much anything I want as long as I don't take it out of light sport parameters.
If I had used the shim, the Pitot tube would have been centered perfectly as shown in the pic at right, eliminating the radial load on the bushing.
Off topic:
I just got back from my 33rd trip to Mecca (a.k.a. Oshkosh). After swearing last year I wouldn't do this drive again, I drove from Longmont, CO to KOSH and back, this year in a rental car (a little over 1000 miles each way). Rental cars in Milwaukee were hard to get and expensive, not to mention the hassle and cost of airfare. Turned out to be a good decision and I'll probably keep doing this even though my airplane will be ready for subsequent years. I'm becoming increasingly nervous about parking my airplane outside in the elements for a week. Maybe I'll change my mind.
In 2020 when I quit splitting my time between NC and CO and moved permanently to CO (selling my beautiful home in NC😢), I kept hearing local pilots talk about flying "over the hill" for breakfast or lunch. Turns out they meant flying over the high mountains along the continental divide (Colorado has 53 peaks higher than 14,000 feet and 600 higher than 13,000 feet). To a country boy from the Carolinas, this seemed like a serious undertaking. I got my chance to try it a month or so ago when we attended an EAA fly-in breakfast in Granby, CO. I got to go back seat in my hangar-neighbor Tom Book's RV-4 (got some stick time including pointers on formation flying). This is a pic I took with my iPhone of my other hangar-neighbor Chad Rennicke's beautiful RV-6. The building which contains my T-hangar has a total of 11 hangars. In this building alone we have an RV-4, RV-6, RV-7, RV-10 under construction and my RV-12.
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