<Archive Thread> Building the EX3 - Tips & Hints

[David H]

Dave (and all kit builders)
EAA helps a lot with this process. Great instructions here:

https://www.eaa.org/eaa/aircraft-bui...uilt-aircraft#


Fantastic colllection of all the forms and how to fill them out correctly the first time. Well worth it:

https://www.eaa.org/Shop/ProductCata...SubTopicID=945

David

[Daveembry]

I agree! That's why I put those links back in my Post #95. haha! Thanks

"I recommend purchasing the EAA publications. Here is a link to the process https://www.eaa.org/eaa/aircraft-bui...built-aircraft and here is the link to their CERTIFICATION GUIDE. I used this for the first plane and it was great with a complete checklist of exactly what you need to do and in the correct order/timing along with all the FAA Forms
needed. https://www.eaa.org/Shop/ProductCata...SubTopicID=945"

Dave (and all kit builders)
EAA helps a lot with this process. Great instructions here:

https://www.eaa.org/eaa/aircraft-bui...uilt-aircraft#


Fantastic colllection of all the forms and how to fill them out correctly the first time. Well worth it:

https://www.eaa.org/Shop/ProductCata...SubTopicID=945

David

[Daveembry]

JURY STRUTS

In the manual around Section 3-27, Page 27-1 starts the jury strut install except it's missing a change for the EX3.

1. the bolt head goes on the inboard side of the strut.

2. Be sure and pay special attention to the torque values on the last page 27.4 especially for the bottom ones because there is a plastic bushing in place, you don’t want to over tighten that and mess up the bushing. That is why it’s only 28 in lbs on the bottom and 40 on the top.

3. IGNORE part about burning holes and installing the pitot tube if you got the G3X with the Gap26 pitot tube. One of the front jury struts has a tube coming out of it. Don’t use that one if you have the G3X. In the kit should be another, regular tube without the perpendicular tube coming out of it. The Gap26 G3X pitot installs into the wing through the bracket that should have been installed when building the wing.

4. There are 2 lengths of jury struts. Since we painted them, there won’t be any parts numbers still attached to them probably but the slightly longer one goes on the aft spars. The rear jury struts should be SC37301-001 and the fronts should be SK37301-001 if you are using the GAP26 pitot (has the AOA). If not using the GAP26 then the front, left should be the SK37301-004 which has the pitot tube aluminum line built in. See the pdf attachment at the bottom of this post for the figure not shown in the manual.

5. Note that there are 2 little shims that have to go under the jury struts. I don't have the part numbers or diagram now but be sure and ask Mitch about the "shims" that must be installed on the EX3. (UPDATE: I ADDED INFO ON THESE PART NUMBERS IN PREVIOUS POST #110 ON THE JURY STRUTS).


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'
ALSO NOTE that Figure FN3-26 on Page 27.3 shows part number SC37301-003 and in fact it should be SK37301-003 (which is what has been shipped to me usually)

AOA PITOT HOSES

If you got the G3X Executive Glass, then you will need to connect the blue and green tubes coming from the wing to the ones in the left wing root. There isn't anything in the Exec. Glass Manual or Finish Manual about this but you need to use the HDW261-739 In Line Connectors and VP9050-007 Inserts. This is the number of these inserts that came with my latest kit. It is the same inserts at the NORMAL HDW-261-765 number. For some reason, this was an alternate number used....so use whichever you have in your kit. These should be in one of the G3X Totes. Do not use any thread sealer.


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FUEL SIGHT GAUGES

FINISH MANUAL PAGE 150 and 276.

The manual says to cut the hose on the lower sight gauge to 4.5” and that is way too long and much harder to cut again later after the wing is on than now. I make them 2.50” and the upper ones at 2.25” instead of the 2.5”.

You will need to trim the actual plastic sight gauge a bit on the TOP only, when you install it. That's easy to do. The lower ones are easier to be sure it's cut to length (about 2.25" long) and go ahead and install the surge preventer into it first, then slide the lower end of the fuel sight gauge plastic (clear) through the header grommet and onto the metal valve. Use a little Armorall again to help.

[Daveembry]

FLIGHT TESTING

Jumping ahead just a bit but we are getting close to flying this sucker. I ordered and received the new FLIGHT TEST MANUAL and FLIGHT TEST CARDS from EAA and they are excellent! I highly recommend ordering this from EAA at https://www.eaa.org/shop/ProductCata...ubTopicID=957# for members it's only $17.95 for EAA members and $22.95 if you aren't.

Most of this info is on the FLIGHT TEST documents in Dropbox, but this has great explanations of each test in the Manual and the cards are great for the cockpit to record stats during the test.

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[Daveembry]

WINDSHIELD

I have 4 videos about this.

Part 1 https://youtu.be/Uc4ga6WI2V4

Part 2 https://youtu.be/8XaI_8H-Nak

Part 3 https://youtu.be/J91JYCZNlcY

Part 4 https://youtu.be/OMjMrUsiVcw


NOTE: THIS FIRST PARAGRAPH IS AN UPDATE IN FEBRUARY, 2020 AFTER DOING ANOTHER WINDSHIELD AND FINDING OUT A FEW THINGS SO GO BY THIS BEFORE READING THE REST OF THE INFO ON THE WINDSHIELD BEFORE AND FOLLOWING IT. IN OTHER WORDS, THIS SUPERSEDES SOME OF THE INFO BELOW.

The order of things to do on the windshield is:

1. Protect the boot cowl with tape or the leftover gerbermask.
2. Mark the 1.5” mark aft of the start of the boot cowl. IGNORE the 2.75” mark the manual says is where the front of the windshield will sit because if you put the liner on the 1.5” mark and the windshield way back there, you will have a huge gap between the liner and the front of the windshield.
3. Set they liner in place with the center of it at the 1.5” mark and clamp the 2 ends level with the bottom of the side windows.
4. Drill #40 holes in the liner as shown in the manual and install clecos.
5. Drill out the holes with the step drill to 3/16” (0.187”) and a G LETTER BIT and install the rivnuts using a little meth glue under the heads. (You can do this now or just use clecos until all the cuts and holes are drilled out since they are faster to use than the screws.)
6. Drill out the liner with a 5/32” (0.156”) step drill bit and then set the windshield up and just hold the liner in place with a couple screws and push the front of the windshield up as far as you can into the liner right at the front, center of the boot cowl.
7. Mark the parts of the windshield that needs trimming where it meets the boot cowl and then cut it. Don’t mark the sides at the A pillars until after you fit it to the boot cowl.
8. Put enough screws/clecos into the liner to hold it loosely in place and set the windshield in place and see if your trim cuts are OK.
9. Once it fits inside the liner OK and then mark the side cuts at the A pillar after being sure the top is level with the wings (using the stick across the wings on the sides).
10. Make the cuts and then place back into position to check. Relevel with the wings at the top and then drill pilot holes through the sides where the wellnuts will go ONLY at this time. Remove it and drill out the side holes using a 3/16” unibit and very heavy countersink.
11. Put windshield back up and in place and confirm side holes are good and clamp in place with the side holes all lined up and then drill pilot holes through the top of the windshield where the 5 rivnuts are in place.
12. Remove and drill/countersink these holes.
13. Apply the tape to the bottom of the windshield and install per manual and video. However, I have NEVER been able to put the windshield in place and remove 1 screw at a time and pull that red backing tape successfully. It always breaks and I have to remove the line almost completely and pull it off and then install the liner.

Pretty much just follow the manual and video for the rest.

I have over120 videos on my Youtube channel showing various parts of the build, including several on installing the windshield. Check them all out here https://youtube.com/user/daveembry85


BELOW IS THE ORIGINAL INFO.

I would change the order up a little from the manual in that I would do everything inside the wing roots first before putting in the windshield. This gives you more room to reach around, etc. Just skip ahead in the manual and connect the fuel lines; pitot tubes and wiring in the wing roots first. Be sure and use the little nylon inserts in the fuel lines before putting them into the fittings. Don't use any fuel lube or thread sealer on these nuts.

The WIRING CHART I did shows where all the wires go to but they are pretty self explanatory.

I would first connect the AOA pitot tube lines; then the fuel lines, then lastly the wires. I would not tie wrap anything now but wait until you are done with everything like windshield and flap rods are done to be sure to have them out of the way properly.

Also, I don't like to install my side windows yet. It's just easier to work all around the windshield, wiring, etc etc. when you can just reach around from any angle and not have anything in the way. I just tape them up in place where they will go so I can mark the front, bottom of each window so I can place the windshield liner to be flush with the bottom of it. I also go ahead and and mark the side and “D” windows for painting. The bottom of the window will line up with the bottom of the windshield liner and the top will line up with the TOP of the same liner, then the front edge of the window will paint just out far enough to cover the metal frame.

The video Mitch did is very good but differs from the manual a bit. The manual says to put the windshield in place and then put the windshield liner to it and the video shows to first lay out the liner and then fit the windshield to the liner. This is the better approach I think because you control where the ends of the liner goes so that it will match perfectly with the bottom of the side window instead of ding it like the manual says which has you following the windshield which would not let the ends line up perfectly without trimming the windshield. IF YOU DO LIKE THE MANUAL SAYS AND FIRST SET DOWN THE WINDSHIELD AND THEN MAKE THE TRIM PIECE GO AROUND IT, THE ENDS WILL NOT MATCH THE SIDES/ENDS AT THE WINDSHIELD AND THE WINDSHIELD WILL NOT FIT PROPERLY. SO IGMORE THE MANUAL ENTIRELY REGARDING THIS.

Mark the center of the liner; mark the center of the boot cowl on the tape or Gerbermask you have covering the paint (aren’t you glad we saved that from the previous parts it was on? It isn't pretty but who cares...it's just to protect the boot cowl). I am going to paint the area on the boot cowl INSIDE to a matt black, so I don't care about protecting that really.

Mark the 1.5” and 2.75” places from the front, upper end of the boot cowl and align the liner center mark on the 1.5” centerline mark and tape into position. NOTE: This 2.75” mark is not right. The windshield will actually sit much closer to the liner so disregard this!.


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Take 2 spring clamps and clamp the 2 sides of the liner on the side fuse tubes so that the bottom of the liner will align with the bottom of the side windows. I haven’t actually installed my side windows yet so they are not in the way. I just held them in position and put a sharpie mark on the boot cowl where the front, bottom of the window are.



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(Here you can see the side window which I have taped in place, and the windshield liner where I have lined it up flush with the bottom of the side window. Also you can see the green, fine line tape I applied on the window for the paint on the bottom and front of the window).

With the liner clamped on the sides to hold it into the correct position and the front on the front mark 1.5" inside the aft part of the lip.......tape it down in a few places so it's flat and start drilling and cleco'ing using #40 bit. The holes have .50" edge distance and are 2" apart. Start them on 1" either side of the center line and then every 2" apart. Don't drill the last 2 on each side yet.

Like the manual says, don’t drill the last 2 holes on either side of the liner. Follow the manual where it says to use a #43 bit and drill through the liner and only far enough to just mark the gerbermask. Then remove the liner and finish drilling the holes using something behind the boot cowl (I use a thin, metal 1’ ruler) to keep from hitting wires.

Then it says to finish the holes using a #3 bit. Wrong! ALL REFERENCES IN THE MANUAL REFERRING TO A #3 BIT IS WRONG. YOU USE A LETTER G INSTEAD. Then we will finish off this hole and the rest with a LETTER G bit later (after first using a unibit 3/16” in the #40 holes we drilled).

Next I like to just take a sharpie and mark the outside of the liner all around....on the tape.


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Remove the cleco's and set the windshield down with the front of it touching where it would sit flush with the liner (set it in place) . It will NOT work if you put it on then 2.75” mark. I also like to measure around the windshield and then find the center of it and put a mark on it so I can line it up with the center of the boot cowl. You can see now where the windshield itself will sit in comparison to the line you drew of the front edge of the liner and you can see the holes you drilled.


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Note that the FRONT of the windshield has a much higher SLANT ANGLE where it goes into the liner at the center, front than it does at the sides. This means that the windshield will sit further away from the front of the liner and drilled holes at the center than they will at the sides where the angle is much less and the windshield itself will go closer to the drilled holes. At the front, the windshield is 1.25" away from the front (the marks we measured and placed.....) and on the side it will be much closer.....more like .75" and almost touching the holes.


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The last 2 I have done needed almost no trimming on the right side (pilot view) but a fair amount on the left (same as in the video). Just mark the windshield. I don't remove ANY of the protective paper until I'm done with all marking and trimming except the 2 sides where I will need to look through the windshield to see the joint in the A pillar that I want to trim to.


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Next I check the fit by putting the windshield in place with the center pushed up inside the window liner and a few clecos in the liner. Get your piece of wood and set across the wings at the top and while being sure the windshield is pushed up as far into the liner in the center.......push/pull on the very top edge of the windshield to get each side to where it touches the wood and maybe pushes it UP just a little. Use a couple spring clamps to hold the top in place, then go inside the cockpit with a sharpie and mark the back edge of the flat piece with the little holes in it that the windshield sits on. We will trim this off. Also, put your sharpie tip through the 5 holes so we can drill them out when we remove the windshield to make the cuts.


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(this is looking up from inside the cockpit at the top of the windshield as it sits on the metal flange with the 5 little holes. Mark the back edge of the windshield where it overhangs the flange and mark the 5 holes onto the windshield.)


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I also go ahead and use my sharpie and draw a line right down the sides where that joint is in the A pillar as well as drawing around the front of the leading edge wing like Mitch describes in the video. After I remove the windshield, I’ll take a long straightedge and draw a new line abut 1/16” away (towards the front) from the joint line I drew and run a piece of tape along the front side of that line. I'll later mark the side holes and drill them after I have all the cuts made and final fitting. Now, everything is marked to trim, so trim the top; both sides; around leading edge wing and bottom of the windshield and check the fit.

One thing to note is that you need to have a very precise hole for the rivnuts to be installed in. The video doesn’t tell you what size drill to use. I think they were using a “concrete bit” for the final hole???? DON'T! It should be a LETTER G bit. Don’t wallow the drill bit around....keep it very consistent. The rivnuts will “spin” when you try to screw in the screw if the holes are too big. The holes should make it so that the rivnut has to be wallowed around, pushed, pressed, etc. to get it into the hole and not just slide in. If they do, they may spin and you can’t get the screw in.

You first use a step drill and go to 3/16" first and then run the LETTER G bit through it. BE SURE AND DON'T WALLOW IT OUT ON THE BOOT COWL! The top piece of metal where the 5 holes are....are really tough to get the rivnuts through BUT THEY WILL GO! Just support the back of that lip with your hand and push and wiggle and cuss and get it to go through.

When you do the boot cowl it will be TOTALLY DIFFERENT! The boot cowl is such thin aluminum.....it will be very easy to over size that hole and much easier to push the rivnuts into the LETTER G holes with minimal pushing, wiggling and cussing. But you don't want to have them just go in easy or you will probably have problems. So it's NORMAL for it to be hard to fit into the hole...but it's suppose to be that way and it will work.

There are good instructions on using the Marson tool (In previous post I showed the model and where to get it) and it works great for me. Hold the rivnut and screw the mandrel down through the rivnut until its just flush with the bottom of the rivnut and then turn loose of the rivnut and turn the mandrel counterclockwise until the top of the rivnut is up flush with the tool head (while the bottom of the mandrel is still flush with the bottom). So, when you go to stick it into the hole, the mandrel should be flush with the bottom of the rivnut and the tip of the rivnut flush with and up against the tool. Insert it and pull the handle and then unscrew it from the rivnut and that's it.


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(Shown is the rivnut mounted on the tool and ready to insert. The mandrel is flush with the bottom of the rivnut and the rivnut head is touching the tool. Just a couple small dabs of Super Glue Gel and it's ready to insert.)

I use the same meth glue that we used on the fuse and put just a little dab under the head of each rivnut before setting to hold it in place. I just put a little on each side of the rivnut under the head before putting it in and just take a paper towel and wipe any excess off after setting it. I’ve never had one spin doing this. I just take a little on the tip of a toothpick and spread it under the head of each rivnut before installing. This gives it a helluva bond. Without doing this, The metal is so thin on the boot cowl, that every time I do it, I have a couple spin out but none with the meth.

Also like Mitch showed in the video, you may take a tap and work any that are hard to screw a screw into. Don’t try and horse it in because you will spin it loose. I actually a 6-32 tap into each one before installing them to make sure they all work good before doing it for real. It only takes a few seconds to do each one and much easier sitting at your workbench and spinning them with your fingers onto the tap. Out of the 30 I used (5 on top of windshield and I have 25 on liner), I had 1 that just wouldn't work.....so I'm really glad they all work great when I install them. Note that when using some meth on the rivnuts, I’ve not had to do this and never had one spin out.


P1060636.jpg
(Running a 6-32 tap through each rivnut before installing)

After I have the rivnuts all set in place and before installing anything, I mask off the boot cowl and other areas leaving the boot cowl that will be inside the cockpit on the boot cowl open so I can paint it. Take a scotchbrite and scuff the paint and I just use a rattle can of black enamel paint.....non-glossy, matt finish and put a good coat of paint there to keep the glare down.


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(All masked off and a coat of black, matt enamel paint is sprayed from a rattle can and left to dry overnight)

continued on next post

[Daveembry]

WINDSHIELD (continued)

When drilling the 5 holes at the top and on both sides of the windshield, we want it to be 1.5 times the size of the screw. The screws are 6-32 and 0.135” wide so that would make it about 0.20” holes which is about a #7 bit. Just use the #1 unibit/stepdrill to the 3rd stop or 3/16” (0.187”).

I first used a #40 and then opened it up with the step drill then aggressively countersink both sides of the holes.


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(Countersunk hole on both sides very deep with the microstop)

Right now the side holes aren’t drilled so FIRST stick the 5 wellnuts on each side into the pre-drilled holes in the fuse BEFORE putting the windshield in place. Its easiest to be sure the bundle of wires and fuel line is out of the way so it doesn’t try and push the wellnuts back out.


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Stick the windshield and liner back back in place and use a #40 bit and drill through the windshield into the center of the wellnut (not going all the way through to the insert that is on the backside).

Remove the windshield and drill and countersink these holes holes as above.

WINDOW A PILLAR WIRING INSTALLTION

Looking at the FINISH MANUAL, Section 3-33, Page 33.1; there is no callout for the tie down straps used for this installation. The correct parts are RM1071-007, CABLE TIES. Note that these are not your standard "tie wraps" because they wrap completely around to install much like a metal clamp instead of coming up through the head of it at a 90 degree angle. I mention this because there is no call-out on this page and the same "type" that I have been receiving from CC are the incorrect ones.....they are too small. Too narrow to drill the hole through. So be sure you have the correct ones before installing.

FN3-28 on Page 31.3 used to have this callout on it but was removed on the latest manual changes for some reason.

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WINDOW LATCHES ON BOTTOM

Now you can go back and follow this post to install the bottom window latches. https://forum.cubcrafters.com/showth...ll=1#post22702

HEADSET HOOKS

If you want hooks for your headsets it’s easier to install them over the top now before you install the skylight. I always get 2 from Cubcrafters. Good suggestion from Pete at CC noting that they should be facing outboard.


P1060648.jpg

AILERON CABLES

Looking at FINISH MANUAL Page 34.5 and figure FN3-34 it is wrong. It was changed. See the WING MANUAL, Page 26.1; W64. The bolt used is NOT an AN3-5. Its way too short. You have to use an AN3-10. Also, no washers go inside the bracket at all and 10L washers are used on the outside under the head and castellated nut AN310-3.

3B8508F2-03B0-4FA0-B876-C6F65F16D69D.jpg

[Pete D]

HEADSET HOOKS

If you want hooks for your headsets it’s easier to install them over the top now before you install the skylight. I always get 2 from Cubcrafters


Attachment 9394

It is highly recommended both headset hooks point outboard. Installed on the same left skylight tube further aft and pointed outboard headsets can still be easily hung on them but they are not pointed at your head!

[Daveembry]

Good idea. I’ll change mine.

It is highly recommended both headset hooks point outboard. Installed on the same left skylight tube further aft and pointed outboard headsets can still be easily hung on them but they are not pointed at your head!

[helios]

I have been following your posts since the beginning. Very informative. At the beginning of my career in Alaska I did some rebuilding of super cubs, as much flying as I could afford, when I had money for gas. Been an AMT in airline industry for the last 30 years. Now that kids are grown I am looking forward to Cubs again, my first love of aviation. I hope to order my own kit in the not too distant future! I do go back and forth on which one, EX2 or EX3, maybe I should just flip a coin.

i hope I’m not stepping on any toes, im trying to be helpful, on your pulley installation I would rather see the washers glued to metal bracket so when pulleys move, the plastic will rub on metal washer not washer rubbing on metal bracket. If this seems petty, please remember most A&P’s myself included are anal about this stuff.

in the recent past, when we had a nut to install in a seemingly impossible location, we would superglue the nut to end of finger to get it started. Ouch! Now we use this stuff, it’s great! No more need for superglue, stick metal to metal, pretty much anything can be stuck together temporarily as long as parts are clean and not too cold. Works like a big chap stick. I have no idea who the company buys it from, but this is who makes it.


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Keep up the most excellent posts on your builds!

[Daveembry]

For sure please jump in any time you have something to add to this thread. I'm just putting in here what I can to try and help others out with what limited knowledge I have and I for sure don't know the best way to do everything and appreciate any advice, tips or suggestions anyone has.

I had also thought about gluing the washers onto the metal bracket itself but I only put a "dot" of the super glue gel on the washer to just hold it long enough to get it installed. I figured that any abrasive force against it would pop it loose but just going onto the bracket is even better. I actually went back and used a razor knife edge and before torquing down the nuts, I popped the washers loose from the pulley.

The "sticky stuff" I always use is Fuel Lube or EZ Turn I guess is the new manufacturer. It's almost too sticky! I try regular grease for alot of things and then the Fuel Lube if it really needs to be sticky and Super Glue last. There have been times where I think super gluing it to my finger tip would work too!!! Will have to try that.

Thanks again and feel free to pitch in any other advice you have.

I have been following your posts since the beginning. Very informative. At the beginning of my career in Alaska I did some rebuilding of super cubs, as much flying as I could afford, when I had money for gas. Been an AMT in airline industry for the last 30 years. Now that kids are grown I am looking forward to Cubs again, my first love of aviation. I hope to order my own kit in the not too distant future! I do go back and forth on which one, EX2 or EX3, maybe I should just flip a coin.

i hope I’m not stepping on any toes, im trying to be helpful, on your pulley installation I would rather see the washers glued to metal bracket so when pulleys move, the plastic will rub on metal washer not washer rubbing on metal bracket. If this seems petty, please remember most A&P’s myself included are anal about this stuff.

in the recent past, when we had a nut to install in a seemingly impossible location, we would superglue the nut to end of finger to get it started. Ouch! Now we use this stuff, it’s great! No more need for superglue, stick metal to metal, pretty much anything can be stuck together temporarily as long as parts are clean and not too cold. Works like a big chap stick. I have no idea who the company buys it from, but this is who makes it.


D711F653-2B1B-4DDA-B48D-B0D58216D6BD.jpg

Keep up the most excellent posts on your builds!