Questions: Boot cowl and prop

[AKKen07]

I’m reassembling my fuselage after taking it to the powder coating shop. I think I am getting to where I have to begin permanently attaching parts like the boot cowl. I am wondering what, if anything, you guys did on the inside of the boot cowl. Did you paint it before riveting parts together? Maybe just prime it? Paint it later? I am planning on just leaving it bare since it is alclad, but it is not without scratches so I realize it might be vulnerable to corrosion down the road. My big hesitation to paint is that I wanted to use Stewart Systems and I cant get that stuff to AK in the winter (it is allergic to cold) so I’d be kinda stuck. Not to mention I really don’t have the facility or compressor for HVLP at this point.
Next question is how far down the road can I put off buying the propeller? I have an engine coming finally but I imagine I can mock something up for cowl formation, right?
Thanks for your input!

[N942VT]

Epoxy prime the backside with locally sourced primer. PPG DP or I like Southern Polyurethanes epoxy. No need to paint if it’s not seen. You will need to know how wide the lip of your spinner backplate will be, with that number you can carry on without the prop. The prop flange face will be your constant.

[Mark Goldberg]

Ken, I recommend you have your prop and spinner in place and use that as the reference to establish the position of your nose bowl. Then you can be sure you have it correct. If you do as Dave suggests using the crankshaft flange and mathematics to position your nose bowl - you stand the chance of not getting it right and wasting time and material. Some builders are capable of doing as Dave suggests. But I have never been comfortable doing anything other than having the prop & spinner in place before starting the cowl. Over the years several builders have tried to get the nose bowl position using drawings from Hartzell or another prop manufacturer - and ending up being unhappy. Mark

[N942VT]

Yes, having the prop is always preferred.

[Rollie]

I primed the inside of my boot cowl and engine cowl with the Stewarts white primer. For a lot of parts that didn't "need" paint, parts that nobody would see, I used rattle can self etching primer. I prepped the metal with a scotchbrite pad and cleaned it with alcohol then sprayed it. I saw it as a little extra protection for the metal without the time and mess of mixing paint and using a spray gun. Plus it gives it a more finished look. I'm happy with the results. I just believe in covering all the bare metal. It still seems wrong when I look inside a Cessna wing or tail during an annual and see all that dull silver/gray.

[robcaldwell]

I covered the inside of my boot cowl with 3M vinyl. https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

And used this primer to create a near permanent bond between the aluminum and the vinyl. https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Protects the aluminum and looks great. Weighs very little.

[Archer39J]

I'll likely be leaving mine bare on the inside. Not worried about corrosion for these parts. Anything else increases the weight, just to keep in mind.

[whee]

I left the inside of my bootcowl unpainted. I live in a very dry environment so corrosion isn't much of a concern. If I lived somewhere not so dry I probably would have used an epoxy primer on the inside.

I agree with Mark about having the prop/spinner installed before building the engine cowl. I'm one of those guys that tried to do it without the spinner and got the measurement just s tiny bit off. But I kinda like the no spinner look.

[AKKen07]

Ok, thanks gents! Guess I’ll wait for the prop to do the cowl. Still have to think about the boot interior.

[jaredyates]

Ok, thanks gents! Guess I’ll wait for the prop to do the cowl. Still have to think about the boot interior.

I left it plain aluminum and never see it. Folks who go looking under places are nosy, there's no need to make things pretty for them!

[AKKen07]

Haha thanks Jared

[gregc]

Internal primer decisions come down to environment and timeframe. I pulled the interior out a C172 where the factory had primed some fuselage skins and left others bare. After 45 years of New England weather, the painted panels were perfect but the bare ones all had moderate surface corrosion.

[svyolo]

Boot cowl and engine cowling are easily removable. You can remove them and paint them any time. I have ended up redoing so many things for me wasting time making a part and painting it right away would just waste more time and effort. I may not paint mine until the first annual.

My build is a bush plane. I won't be painting or priming the interior. If I don't dent or scratch up the boot cowl before it corrodes, I will just make another one down the road.

[AKKen07]

I think I am on the same page. Thank you