Right Spar Countersinking and Nutplates

August 22, 2010

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Well, today was the first official wing construction day. While Van’s is trying to figure out what to do with my damaged left spar, I figured I should get started on the right spar.

First thing…yup…a plans change picture!

The plans for the wing are a little different. There are about 4 separate sheets of different views for the wing. You guys get to see just the general layout one.

Wuhoo! A wing!

Now, let’s get to work. First thing, I very carefully put my beautiful right spar on the edge of the workbench and clamped the flange down very lightly. The spar will tip over onto the table (away from the camera) if the clamps let go, so I’m not too worried about clamping them down too much.

Every builder that has a website makes a comment here about how the construction manual really holds your hand and steps you through the process on the empennage, but then kind of just makes general statements for the wing. For example, the only real construction step on the first page of the wing section says:

“To begin wing construction, rivet the tank skin attach platenuts to the spar as show in DWG 16A, Detail A. Machine countersink the platenut attach holes in the W-706A spar flange.”

Wait. What? That is like 1000 steps, condensed into one statement. It ended up taking me 3.5 hours to do that one step (I admit, I also delved a little into a step a few steps down):

“Attach the K1000-06 platenuts for the W-822 access plate to the W-706A flange. See DWG 12.”

Fine. I see how it’s going to be.

Let’s get started.

Where is my countersink?

A lot of builders start out thinking they should make a nutplate jig and countersink the screw holes before riveting the nutplates (sorry Van, I call them nutplates) on so they can use the jig as a guide for the c/s pilot to avoid chatter. Van’s suggests using the installed nutplates as the pilot guide. After those builders spend some time making those jigs, they eventually abandon the idea and fall back to the Van’s method. I’m going to do something I don’t normally do and FOLLOW THE INSTRUCTIONS. Sometimes, I try to get cute with extra ideas and fancy engineering solutions, when really I should just do things by the book.

So I grabbed my countersink with a #40 c/s bit, tested in some scrap, and positioned the countersink cage over one of the nutplate  attach holes.

The c/s pilot didn’t fit. What?!

You mean I am going to have to drill all of these holes out to #40 first? Ugh!

After drilling every one of the attach holes out to #40, I finally got the countersink and cage loaded back into my cordless drill (slower and more trigger feathering ability than the air-drill) and got to it. Here are my first 10 countersinks.

The blue tape is to prevent metal shavings from getting lodged in between the spar cap bars and the spar web.

Anyway, I continued down the row, being very careful to slow myself down and not to fall into too much of a routine. I could feel this was going to be one of those areas where I would be going through the motions and mess something up. (I did make a mistake while drilling out all the holes to #40. I accidentally drilled out a skin attach hole, too. No biggie, but a perfect example of moving too quickly in a habitual way.)

I stopped about every 6 countersinks and retested my countersink depth using a AN426AD3-4 rivet. They are all perfect. Here is the end of the row, looking back toward the “diagonal” wing-walk attach holes.

Pretty, pretty.

Then, I flipped the spar over and did the bottom flange. Also, there are some access panel nutplate that get attached now, too. I went ahead and countersunk for those attach rivets, also.)

Bottom flange, sobriety-maintaining Sprite-zero, and the girlfriend's cordless drill I'm borrowing (pronounced "you can have it back when you pry it from my cold, dead hands"). Thanks girlfriend!

Phew, that was a lot of countersinking. (I think I counted 144 total countersinks for just the nutplate attach holes. There’s another 72 for the screw holes (in the middle of each set of three holes) I’ll have to do later.)

Next, I grabbed some K1100-08 nutplates, some silver 3/32″ clecos, and some AN426AD3-4 rivets and started getting ready. My plan is to cleco the nutplate to the spar, insert one rivet, then after riveting that one, take the cleco out and rivet the other side.

Cleco in one side, unset rivet in the other.

Down the line, everything ready to rivet.

Redundant picture.

Ahh, this slower, more thoughtful approach is paying off. Can you see the error that I almost made?

Which one of these is not like the other?

Here's an example nutplate before I take the cleco out and put the other rivet in.

I can’t remember why I took this picture. I think I just took out all the clecos, and I thought it looked cool.

Ready to set the second half of the rivets.

No pictures of the second rivets, but here’s one of the other (now top) flange.

You can see all of the nutplates on the lower flange.

Anyway, I set all the nutplate attach rivets on the upper flange, and then called it a day. So I got to cross off the two statements in the construction manual I highlighted above, and next up is to use the installed nutplates as c/s pilot guides for countersinking the screw holes.

Oh, and then I get to repeat on the other spar.

3.5 hours of countersinking and riveting today. 144 rivets, 1 drilled out (the rivet split in two!). Good times.

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Started working on the Elevator Tab

June 20, 2010

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After some more days of not doing anything, I managed to make it out to the Pilots N Paws fly-in today. It was good motivation for working on the airplane.

Anyway, I’ve drilled the left elevator skin to the skeleton, and the next step is really to take everything apart, deburr, dimple, countersink, prep, prime and assemble…

BUT…

I have some things that need to be done first. Mostly, the directions want you to bend the elevator tab “ears.” Well, I don’t think I want to go the bent route. Here’s what I am worried about. I don’t think anyone would really notice, but I don’t love the way this looks.

Bent trim tab ears. I think I'm going to cut mine off and make little ribs.

I think with some work, I could make them look like this, but given how finished these surfaces are, I don’t know if they started as bent ears or riblets.

WHOA! This is awesome. This guy really finished this joint up nicely. Everybody be jealous.

Finally, I found a really nice riblets version. I like this, and this is what I am going to be aiming for (although I am going to try to use solid rivets.

Great finish on the cut-instead-of-bend tab ears. I'm going to strive to make mine like this.

Anyway, I also think cutting the ears off (not bent down in the way) will allow me to use solid rivets in the blind-rivet locations on the top and bottom of the elevator (outboard trim spar rivets). We’ll see.

First step is to get the skeleton re-clecoed in the skin.

The trim spar and the inboard rib.

Van’s wants you to countersink either piece for flush rivets (not for any real flush reason…I think they need to be #40 size holes, and they don’t give you any universal head AN470AD3 rivets). Anyway, per standard practice, I dimpled both.

Dimpled instead of countersunk.

After clecoing together the skin, I am ready to start the headscratching with the tab. Let’s find the tab spar.

There it is.

Let’s go ahead and cut off these tabs. After careful measuring and marking, I’m ready to put blade to metal.

Inboard side. I'm nervous about chopping these off.

Outboard. (see how I lined up the line parallel to the flat portion near the top and to the left of the relief hole near the bottom? This doesn't work. Read on to find out why.

After a quick snip (not too close to my final line) I removed the vinyl from the interior of the skin in preparation for using a file and scotchbrite pad to clean everything up.

Devinling before finishing those cuts.

After working carefully with a file and edge finisher…

Looks good.

Before I really finalize things, I’d like to get my tab placement set up. First, I tried using this extra piece of rudder stiffener.

It worked okay, but I later switched to something a little longer.

After some moving around and fiddling, I re-read the directions, which tell you to bend the elevator ears down along a bend line that is perpendicular to the hinge line. Well, that means that the cut lines should be perpendicular, too. Of course, like I mentioned before, my original outboard line wasn’t perpendicular. All that file work for nothing.

I drew new lines (one on top of the other, ignoring the needed clearance).

Drawing new, perpendicular lines.

Then, I made a “pretty close” cut with the snips. I’ll need to really clean this up, as well as move the line to the left for clearance purposes (I’ll wait until the hinges are drilled to really see what I need. (The instructions call for 3/32″, but that is for the blind rivet head clearance that I won’t have to worry about.)

Pretty close, but still needs trimming and finishing.

Next, I moved back to the tab. Here’s my new line.

I'm bummed because the upper part of the tab, factory provided, is not perpendicular to the hinge line. That means there will be a slight angle there. Bummer.

After getting those refinished, I got the tab mocked up. I kind of worked backward. I want to use the inboard edge and the trailing edge to get placement, then verify I have adequate clearance on the outboard edge and between the tab and elevator for the hinge (there are some hinge dimensions on the plans). I think I’ll have plenty of room.

This looks good, but I'll have to keep trimming that outboard edge.

Here's a closeup. You can see the edge near the top of the tab is angled a little left. This is how it comes from the factory. The marker line and aft portion of the tab are both perfectly perpendicular to the hinge line (line through the center of the rivet holes).

Later this week, I’ll work on getting this perfect, then tackling the riblets that need to be constructed before doing any more work with finishing the skin.

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Riveted E-615PP Trim Reinforcement Plate

April 6, 2010

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WUHOO, tool order arrived!

3 things in the order, $154.90. Ouch.

Also included was this AWESOME sticker.

Where should I put this?

Here?

Here?

Here?

On the airplane? no.

Finally, the air compressor won.

Decorated air compressor.

Look at that beautiful tungsten bucking bar.

Old and new.

Also, I got two more dimple die sets. #6 and #8, on the right.

Just for comparison. #40, #30, #6, #8. Still need a #10.

Alright, back to work. First up, using the #6 dimple dies on the E-616PP Trim Cover Plate.

Nicely dimpled. I don't think it matters that you take off the blue vinyl. Maybe that was a bad idea.

Here’s the bottom side (top side when mounted on the bottom of the elevator on the airplane).

Peeling off the blue vinyl.

Then, edge finished and scuffed for priming. I’m going to wait to prime this until I can actually by the electric trim motor since you have to drill more holes. Just thinking ahead: can I countersink and use NAS rivets for the trim motor mounting brackets? Nope. These are pretty structural (hold the motor, and therefore the trim tab, in place.) I’m sure those directions will confirm the need to dimple. I’ll need to dimple E-616PP and the brackets that are used to attach the trim motor.

Ready for priming, except for all of the extra holes I have to drill, deburr, dimple, and rivet.

Same deal on E-615PP.

Ready for priming.

On the fancy priming stand.

After shooting primer to one side of E-615PP, I decided to add 4 holes for each of my new dimple die halves.

4 holes drilled.

Tada.

7/32″ seems to work well for holes in a home-made dimple die holder stand.

7/32" is a good size hole for these.

Then, I shot primer on the other side of E-615PP. While I waited for that side to dry, I edge finished E-616PP.

Look at that nice edge. I love the scotchbrite wheel.

Now that E-615PP is dry, let’s do some riveting! I grabbed the K1100-06 nutplates (or platenuts as Van calls them) and the 14 required rivets. Remember from March 28th, I am using NAS1097 rivets here.

I am going to be using NAS1097 rivets here (smaller head than AN426 rivets) so I can countersink (instead of dimple) the holes here. That saves me from having to dimple the nutplate ears, which will save me a lot of hassle.

I finally found the rivet callouts.

I thought that because I countersank (verb tense?) the reinforcement plate that the 3.5 would be way too long, but the -3 was definitely too short. I grabbed 14 NAS1097AD3-3.5 rivets.

-3.5 (length) should work here.

I put all of the nutplates in with a single cleco and a single rivet, taped into place before starting to squeeze them. I hindsight, I should have backriveted these. So dumb.

Half of them done.

Then I did the other half.

Nice and flush. There is one that is almost proud, but doesn't affect the cover plate, so I may not try to muck it up further by drilling it out. We'll see if I can sleep tonight.

Once I got those 14 set, I grabbed the An507-6R6 screws and got the cover plate screwed on.

Ready to screw down. see in the lower left where the shadow under E-616PP is a little bigger? The dimpling kind of warped the plate. I'll have to try to coax this flat again.

I couldn't get the screws in all the way without a lot of effort. Is this normal for nutplates?

Anyway, 14 rivets set in just under an hour. I’m going to mark an hour today (a little long), then short myself on a post in the near future.

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