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RV-12 Cowling fitting success before powerplant installation?

scottmillhouse

scottmillhouse

Well Known Member
Building a legacy RV-12 and still waiting for my powerplant/firewall forward kit that was supposed to be crated in November. I would prefer to not do the cowl fitting until after powerplant installation to insure proper fit but I'm running out of things to do. By plans it is done before engine installation. How successful has that been for folks that fitted before powerplant installation? In particular for centering the spinner and getting proper cowling to spinner gaps.

OK, I was right to wait to after engine installation for my first build and I will do that again. Was just hopeful that somehow Vans had the scribes right and I could fit the cowl while I wait.
 
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I don't know about the Legacy 12, but you can't do it on the 12iS. You have to have the spinner plate installed because the alignment of the front of the cowl is determined by it. You actually clamp the cowl to the spinner (with spacers) as you fit the pieces together.
 
FlyingDiver said:
I don't know about the Legacy 12, but you can't do it on the 12iS. You have to have the spinner plate installed because the alignment of the front of the cowl is determined by it. You actually clamp the cowl to the spinner (with spacers) as you fit the pieces together.
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That is basically how you do it in other RVs I built and how I did it on my previous 12 but the legacy 12 instructions had you cut to scribe and fit. I was considering doing it now while I wait so I could paint the fuselage without concern of marking it up fitting the cowl.
 
I installed the cowl (legacy circa 2013) using just the factory scribe lines and it worked out fine for me. Having said that I think that having the engine/spinner in place prior to final fitting of the cowl is preferable.
 
I waited until the engine was mounted and I am glad I did. I had to remove excess material on the left side to get the cowl centered with the spinner. If the hinges were already mounted it would have been a pain to fix it.
 
I think you can do the part where you mate the upper and lower halves, but don't try to do anything with the aft edges until you have the engine mounted.
 
I was fortunate to have my finish kit and power plant kit delivered together. I installed the engine and then fit the cowl and would recommend this sequence. I helped with a 12iS and we did this same sequence, engine then cowl.
 
On my legacy 12 the fit based on the scribe lines was so far off I was worried there was something wrong with the engine mount. There wasn't.
 
I built a legacy RV-12 and in contrary to the KAI I first installed the engine and then cut and fit the cowling. It definitely can be done that way plus it allows for more precise distance between spinner back plate and cowl.
 

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I'm installing my cowlings now. I was waiting for my power plant kit several months ago and I asked Van's support about installing the cowlings before the engine and the indication was that it couldn't or at least shouldn't be done. My engine was installed a couple of weeks ago and I don't see how the cowlings could be installed without the spinner back plate for spacing and support. I'm impressed with how close the scribe lines are to my final trim but even when it is 1/16 inch off, do you want that much of a gap between the fuselage and the cowlings? I don't!

You can certainly do some of the pre -trimming of the cowls, making the hinges, etc. Then you'll be ready when the engine comes.

Interesting side note. I had the same issue years ago with a previous build as the engine (a 912ULS for a kitfox) was delayed. They even had plans for a jig that could be built out of plywood to simulate the engine for cowl installation. Kitfox support at that time said to wait. I'd be much happier with the final result. So I did.

Henry
 
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When I took the Synergy weekend class in Atlanta, they said to wait to fit the cowlings until after the engine had been run a couple of times. They said there would be some sagging of the front of the engine as the Lord bushings compressed.
 
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