<Archive Thread> Building the EX3 - Tips & Hints

[Daveembry]

Absolutely agree! It’s just nice to know how much is left there in the straight and level, static configuration. Ram air pressure into the fuel caps may play a roll also. Certainly I would never rely on that myself or recommend anyone else do either.

It’s also nice to know how much fuel the tanks really hold in the 3 point config.

Thanks for the additional info.

Dave - Great video and very informative as always! The purpose of building an EAB aircraft is education and recreation, and that is a very educational video on how much fuel can still remain in the system even after the placarded amount of useable fuel has been consumed.

Our designers (and FAA regulations) are conservative, and CubCrafters designs, tests, and placards the aircraft to always ensure that enough fuel remains in the system for the engine to continue making power throughout all phases of flight, including various pitch and roll attitudes other than straight and level.

The FAA’s guidance for amateur builders to determine the amount of unusable fuel on their EAB aircraft is on Page 33 of AC 90-89B, which I have linked below. In part, the guidance is to determine unusable fuel at a pitch attitude 5 degrees above the highest anticipated climb angle that the aircraft can achieve. That same Advisory Circular also offers guidance to amateur builders (on Page 17) as how to calibrate their fuel tank indicators. We recommend that amateur builders follow that guidance when building or testing any CubCrafters kit aircraft.

https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_90-89B.pdf

I know you said it in the video, but to emphasize in case anyone out there missed it; it is not safe to run any CubCrafters aircraft down to 1.4 gallons of fuel remaining in the system. At any fuel amount that is less than what is placarded as useable, the aircraft operator is at risk of a loss of power due to fuel starvation.

[RBruhn]

Dave — I really appreciate all the effort to share your experience. I’m just starting with my EX-3 build and figuring out the best way to reference the manual, forum posts, and my own intuition (last.)

For the last year I’ve read about the dreaded cherry max rivets and I pulled some in preparation for this build. I’ve just pulled my first real ones on the jury struts and wondered if I might get some expert opinions. I’ve scoured the videos, forum posts, and even VAF to find examples of what ‘good’ looks like and suspect this has been answered before although I couldn’t find it this evening. The side closest to the squeezer looks fine to me but I wonder if the formed head (I might have the terminology backwards) looks usable but not pretty. Are these good or should I start practicing to remove them? (Center punch the mandrel, etc.). If not good, could you upload an example or two of a good one? (Both sides)

Thank you.

Matt
San Antonio

[Daveembry]

Hi Matt,

From what I can see, they look good to me. The cherrymax stem should be flush on the top where it breaks at the head. If you have the rivet gun cocked sideways where it isn’t sitting flush against the head of the rivet when you pull it, the stem can break off prematurely before it upsets or expands the back of the rivet where it locks in. If it does, you will see a hole looking down into the head where the stem broke off below the top of it and the back of the rivet will not be “mushroomed” or expanded out where the end of the mandrel or stem is. That part will be the normal size and the stem sticking out further. Look at a couple of drawings I put below.

068C8943-D5AC-4E90-AC5C-6FE5BDC302E5.jpg


If you look at the backside, you’ll see that it hasn’t expanded all the way and you’ll see part of the end of the stem sticking out because it didn’t fully seat. if it’s set all the way, the end of the stem part will be right up against the expanded part like yours are. I don’t have any photos of the backsides handy. It takes a lot more “pulling” to get the cherry rivet set into the locking ring and if you don’t have the gun flush and pull it at an angle, the stem (mandrel) may break before it sets leaving the stem broke off below the head and the backside not expanded with more stem sticking out.

85F543CB-2752-4CB0-A66E-D7DDD21CC097.jpg

They really aren’t hard to pull at all normally. Just be sure you keep the rivet gun flat against the head of the rivet completely as you pull it. That’s easy until you have to pull the “hard ones soon”, in the machined ribs. These in the photo are the hard ones because it’s very hard to get that rivet gun tip flush. I describe it more in this post https://forum.cubcrafters.com/showth...ll=1#post21588

I’ll try and get more photos for you but I think you got it right here. That stem breaking flush with the head is good.

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Dave — I really appreciate all the effort to share your experience. I’m just starting with my EX-3 build and figuring out the best way to reference the manual, forum posts, and my own intuition (last.)

For the last year I’ve read about the dreaded cherry max rivets and I pulled some in preparation for this build. I’ve just pulled my first real ones on the jury struts and wondered if I might get some expert opinions. I’ve scoured the videos, forum posts, and even VAF to find examples of what ‘good’ looks like and suspect this has been answered before although I couldn’t find it this evening. The side closest to the squeezer looks fine to me but I wonder if the formed head (I might have the terminology backwards) looks usable but not pretty. Are these good or should I start practicing to remove them? (Center punch the mandrel, etc.). If not good, could you upload an example or two of a good one? (Both sides)

Thank you.

Matt
San Antonio

[RBruhn]

Thank you Dave! I appreciate the additional material too.

[Daveembry]

Welcome to “MERICA”. Free to fly. #7

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[PBY Catalina]

Whaouw !!!! Dave it's a beautiful peint job !!! Congratulations !!!

[Dan L]

What a beautiful plane! Very nice workmanship.

[Daveembry]

thanks! How’s yours coming along?

Whaouw !!!! Dave it's a beautiful peint job !!! Congratulations !!!

[PBY Catalina]

thanks! How’s yours coming along?

Slowly but well.
I'm going to tell an update here.

[ceslaw]

Very impressive.

Who designs the paint and graphics? Very creative.