40-04, landing light ribs

Well, just because I buggered up the wing is no excuse to not get something done.  I finished up the ribs anyway and set them aside for later installation.

Damn. A $150 mistake

Well, I made a pretty good “oops” the other day (12-16-13).  (I typically post on this blog when things are slow at work, and I actually had several days off, so I’m late posting here.)

Take a good look at the photo, see if you can see what’s wrong.  I’ll give you a hint: the landing light ribs aren’t making contact with the lower surface of the wing—why not?

Major Oops!

Looking inside the hole cut in the leading edge of the wing, you can see the outer landing light rib clecoed to the upper surface of the wing, but it’s a good 1” away from the lower surface.  The paper template was aligned with the rivet holes on the outside edge and the next rib inboard.  (I originally used a strip of tape from the marks on the paper to the holes to verify good alignment.)  So what’s up?

Look all the way at the very left edge of the picture.  (BTW, I took this picture in preparation for posting a plea for a diagnosis on VAF.  Right after I took the picture, I saw the problem.)    I lined up the template with rivet holes #2 - 4, instead of #1 - 3.   I just didn’t see hole #1, probably because it’s got an inverted cleco sticking out of it.  Damn.

As soon as I figured it out, I sat down and ordered a replacement W-1203-R, list price of $85 (with a footnote saying shipping will be added).  I was very pleasantly surprised to get a notification from the bank that my card was charged only $143 on the 18th, and a FedEx note saying that I should get delivery on the 24th.  Not nearly as bad as it could have been.  The last bit of penance for this oops is drilling out about 300 rivets to take off the ruined skin.

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Dec 23rd

The new skin arrived today.  When I got home from work this morning I could see a nice tall box left out on the front porch.  Only problem was the box was kinda square, not exactly the shape I was expecting.  To be more descriptive, it was about 5’ tall but roughly 18” x 24” (no, I’m not OCD enough to have measured it).  I didn’t think that the wing skin could be in there and that I received the wrong part.  Much to my surprise, the skin was rolled up like a newspaper and standing on edge.

Replacement W-1203-R 

Note the highlight on the surface closest to the camera:  it’s actually the leading edge fold  that has been opened up instead of folded closed.  I’m amazed at how springy the aluminum is and that it doesn’t encounter plastic deformation with these manipulations.  Below is a picture with the duct tape cut and the skin placed on the injured wing, over the skin it will replace.

Replacement Skin, pre-positioned

Now all I have to do is find the time to drill out the ~300 rivets to remove the 1st skin.  BTW, I did drill out the 20 rivets on the upper surface.  I broke my #52 bit in the process...  :-(

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Dec 28, 2013

OK, got the skin off.  I learned quite a few drilling-out-rivet techniques.  At first I used a #52 from the local hardware store to drill out the steel ‘pits’ as I have taken to calling them.  That lasted about 5 rivets before the cheap bit broke.  Then I went to using a #40 bit and following with a #30.  Towards the 2nd half of the project, I just went with the #30 and got very good at quickly popping off just the heads and then lightly drilling until the stressed skin suddenly released its tension and could be moved.  After I remembered to remove all of the cleverly hidden (inside) clecos, the skin came off nicely.  I then returned to the naked ribs and drilled out the bottom halves of the rivets.

Not surprisingly, there are some ugly holes due to drill bit wandering as it tried to go through the steel pits and ended up going to one side or another.

Example Ugly Hole #1

Example Ugly Hole #2

I posted the following on Van’s Air Force. For now, I’m closing down the shop and enjoying another 24 of my 60 hour vacation.

Hi guys,

I'm looking for confirmation (or not) that I'm doing a repair correctly. I screwed up the landing light cutout on the R outboard leading edge wing skin, thus I spent all day today removing said skin in order to replace it. I have drilled out all of the rivets and removed the skin itself. Not surprisingly, some of the drilled out holes are out of tolerance for being re-riveted.

Question #1: I'm using 50 % out of round as my upper limit of acceptable for re-riveting. Is this reasonable? I can't remember where I learned it, and haven't had much luck finding the original reference (if it exists.)

Question #2: Assuming the above criteria, I have about 20 holes that will need something other than an LP4-3. I have some 5/32" rivets from the local hardware store. Is it acceptable to match drill the new skin with a 5/32" bit and use those rivets?

Thanks for any feedback,
-dbh

 

December 30th, 2013

I got a lot of feedback about not using store bought rivets because they have no specifications, so you can’t tell if they are adequate.  On the other hand, I certainly couldn’t find any specs for Van’s LP4-3’s.  One VAF poster sent this link (http://blindrivets.gesipausa.com/vie...-steel-mandrel) to a rivet company with the claim that their product was, in fact, Van’s LP4-3.  It certainly looks like an LP4-3, so I’m going with it.  I requested a comparable 5/32” rivet via their web page, but I think they’re closed for the holiday week.  I’ll mark the following holes as “do not rivet” when I attach the skin later this week:  

Larger Rivets

Ribs are counted from outboard edge

Holes are counted from main spar

 

#2 Nose Rib 20

 

#2 Main Rib 11, 

 

#3 Nose Rib 1, 22

 

#3 Main Rib 1, 9, 10, 13, 23

 

#4 Nose Rib 1, 15, 16, 18

Not too bad; a total of 13 rivets out of > 300 drilled out.  BTW, no one commented on my criterion of “> 50 % out of round.”  The more I though about it, the less sure I could be objective about what constituted 50 % out of round.  I used a more objective criterion:  I placed an LP4-3 into each hole.  If I could see any hole beyond the edge of the rivet, then I called it “oversized” and put it on the above list.  

Anyway, Nick & I put the skin on and I clecoed it in place.  I’ll rivet it later this week.

 Replacement Right Lower Outboard Skin

January 2, 2014

OK.  The new skin is replaced, with the exception of the 13 oversized rivets to be placed upon their arrival.  The rest of the rivets were placed w/o any difficulty.   Total time: 16 days.  Total cost ~$200.  I guess that counts as a learning experience!

17-02 RIGHT, Right Lower Wing Skins

I’ve had several days of working on attaching the lower skins to the Right wing.  I’ve actually accomplished a little bit more than what is called out on page 17-02, as I have also riveted the leading edges.  This wing was ribbed and skinned while on saw horses, so that the chord was vertical.  As mentioned elsewhere, I did this to avoid possibly bending the ribs, but also to learn different ways of doing things.  I was surprised at how much sag there was in the middle of the span, and I needed to put some support under the rear spar to allow the skins to line up with the holes.  All in all, very boring repetitive work, but intensely satisfying.

Clecoed in place

 

Riveted in place
(lower surface only, in this picture.  You can see some clecos peaking over the leading edge.) 

 

Next step will be another detour to chapter 40, to install the landing light.  I want to leave the upper skins off while I install that light, as I have a sneaky feeling that being able to reach from behind will be very helpful.  Once the light is in place, the upper skins go on and I build out the wing tips and the inboard edges as per plans.

Bob pointed out that I won’t be able to finish the wingtip lights since they require fiberglass / epoxy work, and that needs ambient temps above 70 °F.  Since it’s a pleasant 15 °F right now, I expect that that will be a spring time project.

EAA Tech Counselor Visit

Major Milestone!
On Monday, Dec 9th, I had my first visit from an EAA Technical Counselor.  He showed up at the house/shop and looked over the work to date.  We chatted a bit about my initial issues with the rudder, various metal working techniques, the pros & cons of E-LSA vs EAB, the pros & cons of deburring every edge, tips for recalcitrant rivets, local politics, technical support from Vans, advice from VAF, etc.  When all was said (but nothing much was done), he said I was doing fine and that we’d do this again 4 or 5 times as my build progresses.
To quote: “Project looks good and appears to be coming along fine.  I found no issues with the project.  We discussed several items that were corrected prior to my visit."

40-05, wing wiring connectors

I ran all of the wires for the wings before putting on the skins.  While it was easier to see the grommets and run the wires, I fretted about bending the ribs excessively.  Engineering is always about tradeoffs and this was a perfect example.  Although there were no actual problems, I can see that having the skins on would have provided much more stability to the ribs during the pulling process.  Live & learn.

Anyway, here are the pictures of the R & L wing electrical connectors.  Note the R wing has the female half and the L is male for the floating connectors.  These are interesting connectors: the female is mounted with deliberately loose bushings and there are 3 cm long pin/sockets to allow a little bit of wiggle room (imperfect alignment) as the parts are mated.

I purchased another set and will make a test jig with 12 Vdc and some switches so I can power up the lights after they are installed.  I’d much rather debug anything ‘in situ’ rather than finding out that there’s problem when I’m integrating the wings and the fuselage. 

 

Left wing with male connector.  Note the string tied through the lightening holes.  Not sure why they requested that I put another string in after the wires are pulled, but that’s what the plans call for, so it’s there. 

 

 

15-07, R wing nose ribs

while on a roll, I continued after getting the main ribs on the R wing and attached the nose ribs without any complications.  It felt good to work on the plane today, even if it cost me two hours of sleep...

 

Clecoed in place, confirming all are aligned well.  This photo is aligned along the notches on the upper surface.  Note the electrical connector, pre-installed.

 

 

R wing with all ribs and spars.    Next:  skins!

15-06, R wing main ribs

Many days of little bits of progress, but I finally got the main ribs on the R wing spar.

 The first thing I did for the ribs was pull all of the blue plastic off.  Took 45 min to strip 28 ribs.  I remember reading that heat helps the adhesive to peel off, but my garage was pretty cold.  I use this propane ‘torpedo’ heater to warm things up.  I discovered that holding the blue rib in front of the blast from the torpedo would warm it up in about 5 seconds and greatly facilitated removing the snake skins.  You can see the pile I created in the process.

Here’s a pretty typical shot, the main ribs are clecoed in place and I am verifying that things align well before proceeding with rivets.

 

Another view of the clecoed ribs.  

 

 

OK, take a close look at the rivet on the vertical surface in this before & after pair.  Do you see the slight gap in the 1st photo?  The reason I took those pictures is because I noted that I hadn’t gotten a good, firm seat of the rivet before pulling the trigger, so it was “loose.”  I simply noted it, put down the rivet gun and reached for my #52 drill to drill it out before I realized that this was just a matter of fact and not one that got me all worked up about having to remove a rivet.  OK, enough of demonstrating that I’m growing up. :)

 

Main ribs in place, with rear spar attached. 

 

 

Another of my ‘favorite view’ shots.

Decision: E-LSA

I’ve got an interesting job.  I work the night shift at a small ER in rural Ohio.  Sometimes we have patients waiting for hours to be seen, other times we are bored silly.  Tonight would be the latter, so I have time to post a blog, even if there’s no progress (regarding building) to report.

One of my other aviation hobbies (besides building ‘012) is collecting ratings.  I currently hold a CFI-Airplane and am studying to add on CFI-Instrument.  I don’t instruct for a living, and have only accumulated about 17 hours of Dual Given since I earned that ticket 2 years ago.  Nonetheless, it’s that CFI-A that finally helped me to decide that N76012 will be an E-LSA with any customizations done after obtaining her airworthiness certificate.

What’s that, you say?  How do those facts fit together?  Simple.  You may not use an EAB aircraft for commercial purposes.  I might, just might, get a fancy to do instruction in 012.  Can’t do that if she’s EAB, but it is legal if she’s an E-LSA.  All of the other advantages of potential sell-ability, no need for the dreaded ‘Experimental’ warning / label, and potentially lower insurance all apply.  

I will be meeting with an EAA Tech Inspector next week.  I’ll check with him how much provisioning for future modifications may be made without endangering the E-LSA designation.  I’ll do whatever is easy to do during assembly, as long as it doesn’t put that E-LSA at risk.  I will also have to work with the FSDO and the bank to change the paperwork that has already been started by First Pryority Bank, since they have established their lien on the plane by legally creating it as an EAB.  Those bridges can be crossed.

Oh, by the way, work is seriously interfering with my life.  I’m working 10 out of 11 days right now, and have had no appreciable time to make any progress in the garage.  Just so you know, I’ve started work on the R wing and have half of the main ribs attached to the main spar.  I don’t expect that I’ll have any shop time until the 11th... :(

talk to you then,

-dbh