EX3 wing manual tips and suggestions

[NKAP]

Hello, this is my first post here, hopefully this is in the right area. The main reason I joined the forum was to make a post about the issues and confusing parts in the wing manual for the EX3. Hopefully I can keep others from getting frustrated like me. I am very meticulous and like to follow directions very carefully. My building partner and I are working on building the EX3 and both of us are having a hard time with some sections of the manuals. I will say that every time we called Mitch he was happy to help us and clarified the section that we were on, but it would be helpful if the manual included all the info that was needed.

I think some of the issues come from the manual being based on the earlier models EX1 and 2 and just being updated instead of re-written. One thing I found out is that you CANNOT WORK STEP BY STEP thru the manual, you have to read ahead to the next few sections before doing the work. Here are some of the things I have noticed so far, I will continue to update as we go.

Page 49: Figure W4 shows no washers on the rear spar detail A but shows 2 washers on the rear spar detail B, we assumed that there was one per side and built it that way, so far no clearance issues.

Page 52: The prevailing torque IS included in the torque values with the locknut so don't add in your prevailing torque to the numbers given. We called Mitch to verify this.

Page 56: The holes for the rivet on the top front of the ribs on figure W6, make sure you leave yourself some room to fit the rivet puller to rivet the rib to the spar. (don't drill the hole right next to the spar attachment rivet hole)

Page 69: There are no predrilled holes for the nut plates at 72" from the wing attach fitting, there are holes at 94" from the wing attach fitting, (hopefully this is what they are for)

Page 76: Before installing fuel tanks permanently with the lock nuts you may want to square the wing first

Page 77: The small wires will also need to be drilled out per installation drawing on page 53 with 3/16" bit (easy to miss the note on figure w5, says drill holes to .188 on installation).

Page: 89-93: Read the whole thing before starting, it looks like they only use the rear spar to square but later on page 92 it says to string both spars and have the fuel tanks out when tensioning the wires (reason to not install the locknuts yet on page 76)

Page 101,104,105: The diagram says not to install the rivets in a certain area, but you DO need to install the flush mount cherrymax per diagram W33 before mounting pulley assembly. Also on photo 119 (page 105) it shows the rivet next to the pulley mount installed, (still going to need clarification if this one should be installed or not).

Page 106: When installing the trailing edge ribs if you follow the instructions it will have you install the rivets per drawing, except rib 8 and 9 do not attach to spar yet, BUT the rivets in the side of 8 and 9 are not mentioned. Then it says to put the reinforcement plate on this area (I assume not on top of the AN470 rivet) still waiting for clarification for the one.

Also in general through out the manual, make sure you sand and clean up any rough edges on the trimmed and filed aluminum so as to prevent cracks from forming, this should go without saying but one may just file and fit as per the manual. DO use the FAA Advisory circular 43.13 for reference, it is free online and has lots of good info.

These were the main things I was confused about, so if you do have any trouble don't hesitate to call up Cub Crafters and clarify. There are a few other things that can be irritating in the manual but these are the main ones. Hopefully these tips will be able to help someone to know what to look for. I am only up to the trailing ribs but I will keep adding as I find more things.

[Mitch]

Nathan

I really appreciate all builder feedback and am eager to change the manual when necessary. All of the manual changes that are between revisions are in the DropBox version(online).As always I recommend that a builder reads the entire manual before starting the build. This will hopefully give you an overall understanding of the build process. I am going to talk about your first comment.

On page 49 FigureW4 detail A shows that the bolts are installed without washers under the head. This part is a critical wing attach point, so we use close tolerance bolts and are looking for maximum bolt shank inside the fitting. That is why there isn’t a washer under the bolt head. AN bolts are different than standard bolts that you purchase from a hardware store, they have a washer machined into the head just for this reason. We also calculate the bolt length and do not want the nut to bottom out on the shank before the proper torque is achieved. That is why Spar detail B has two washers under the nut.

Thanks
Mitch

[NKAP]

Thanks for the feedback for page 49. I will get that changed right away.