dbhill916

dbhill916

Well Known Member
Patron
Hi guys,

I had a heck of a time with my landing light, and I don't think it's possible to install it according to plans. That means I'm doing something wrong, so I'm looking for feedback before I pull any more rivets.

When I looked at chapter 40, I was very concerned about trying to install the landing light through the leading edge opening, so I elected to do the installation prior to placing the top skin. After fitting everything in this morning, I'm convinced that that's the only way to do it. The original sheet of Lexan was far too large to place through the cut out, so I assumed that folks following the instructions (retrofitting?) would have to make a rough cut, then final cuts. Today, I put in the ribs and light from behind and tried to fit the lens in through the cut out. I was unable to figure out a method of placing it inside the wing to even attempt starting the screws.

The photo below shows everything clecoed in place. I reached this point by removing everything and installing the lens, then the light assembly and ribs and finally the connector. All of the assembly was from the back and though the lightening hole of the outside nose rib.

Like I said, I think I'm doing something wrong and want some feedback before I rivet the LL ribs.

IMG_0151.jpg


I'm also not happy with the sloppy appearance of the cutout. Are there any techniques for smoothing out the wrinkle in the upper right corner? Are there any techniques for getting the upper and lower edges of the cutout to fit against the Lexan?

Thanks for any comments
-dbh
 
Dave,

I just recently finished my landing light install and had the same problems as you......................with pretty much the same solution. I did run across a thread from the past talking about this, so you might also search for that.

I'll answer in more detail tomorrow, but do have one question right now. I can't tell from your description if you trimmed the landing light lens to match the supplied template or not?

Jim
 
If the lens is trimmed flush to the edge of he metal backing plates at the top and bottom edges as described in the KAI, the lens will slip laterally through the opening (outboard, moving towards inboard) if you squeeze it ever so slightly.

About the puckers? It is hard to tell what might be the cause from that one photo. One thing I do see is it doesn't look like the screw dimples are fully formed (the screws appear to be sitting kind of high above the skin surface). Puckers like this can be caused by the lens not being fully fwd and tight against the L.E. skin.
 
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Jim -- I trimmed the LE to the template as per the book. (Actually, I screwed up by mis-aligning my template on the first LE skin, had to drill out over 300 rivets to remove it and replace it.) The cutout was as close to the template as I could make it. I drew a marker inside the paper cutout and then trimmed the metal to the edge of the marker; that would have reduced the size of the opening by a couple of 32's.

Scott -- Thanks for the comments. I can certainly re-dimple the LE skins. I've not done too many dimples and I'm probably still in the "easier to do more later..." mode. I'll try squeezing the lens out as described and report back in a few days.

Do you think that there's room for me to Dremel the cutout closer to the screw holes? It sounds like the couple of 32's mentioned above might be enough to prevent the fit. (If I do that, I might be able to shave away some of the wrinkle in the right upper corner, too!)

-dbh
 
DBH,

Suggest you remove the lens and see if the wrinkle is still there without the pressure of the lens screwed to it. It is possible your holes are slightly misaligned and that tension is pulling the metal into that little pucker. If so you could enlarge the holes SLIGHTLY to release the pressure. Also what Scott says, fully dimple your holes.

It is nearly impossible to maneuver the lens in and out of the opening with nothing to hang on to. Use masking tape to make a "handle" that you can grab. Don't remember if that's suggested in the plans or not.

As to the fit of the lens to the skin- if it's not right you may have to re drill the mounting holes, and that may not be possible without getting a new piece of plexi, that you can get from Vans at nominal cost.

Good luck, and let us know how it goes.
 
Check the scale of the template used

David-
I would have had a similar issue I believe ? About this time last year prior to marking, cutting and drilling holes, I noticed when placing the backing strips over the drilling template, did not align correctly ... in fact, it was way off as you can clearly see in the following photo.
DSC03530.JPG


The bottom line, the paper template Van?s supplied in the plans was printed to the wrong scale. Van?s was contacted and new drawings were sent to me ? Also as a side note, I pressed Van?s about the dimensions they stated in section 3-04 for the size of a template sheet which still did not match dimensions stated in 3-04 ? however, the holes aligned perfectly on the new drawings but the overall dimensions of the drawing at the borders did not match what was called for in section 3-04 of the plans. Was told they would look into it.

By this time it was around Sun-N-Fun so a week or so after the show I wanted feedback and closure about the dimensions called out in section 3-04 so called Van's again was told they had an error on the plans. The dimensions stated in my plans for the templates were 16? x 10 5/16? at the borders. Van?s told me that that was a misprint and the template page dimensions should be 16? x 10 9/16? at the borders. I posted the new information here at that time.

If the template WAS off ? then would suggest you make new backing strips to match the holes you already drilled. This should help relax the metal some.

Happy Building,
 
Dave,

Here's a couple of more threads I found talking about this issue:

http://www.vansairforce.com/community/showthread.php?t=101667&highlight=lens

http://www.vansairforce.com/community/showthread.php?t=78980&highlight=lens

Before the top wing skins went on or the lens was installed I installed the pins on the wires running through the wing. Then I installed the lens from the back. At this time I ran a silicon fillet around the lens. Then I installed the light and supporting ribs. Then put the connectors together.

After I have my Airworthiness Inspection completed and before painting I'll cut an access hatch, just like the one for the stall warning hatch, under the landing light for access to service the light or connectors if needed.

I agree with Scott about your dimpling being a little shallow. Also I had to countersink the lens quite a lot in order for the wing skin dimples to have room to drop completely in. I made a test dimple on scrap to check my depth.

Jim
 
David, I just finished installing the lighting kit in my already flying 12 last week, and it had it's moments. All the suggestions posted thus far are good ones. Only thing I'd add to is fit the holdown plates to the lens per plans and then cut lens all the way back to the outside edge of the top and bottom plates. I also cut the width to allow only 1/2" on either side of the cutout. Then using tape to hold the lens it will slip in and out (almost) easily. Until I trimmed lens back to that point it was near impossible to insert ,and I was concerned I would break or scratch the lens trying to place it, and replace it, which I had to do a dozen times or so.
Another point is I can't tell from the picture of the lens installation, but make certain you have allowed enough space in the cutout to secure/remove the screws holding the LL200 to the brackets. If you followed the plan cutout and positon it should be ok, but it is very tight. Installing/removing screws w/o a top wing skin is a lot different than working thru the cutout.
Dick Seiders 120093
 
Check the shape of the lens

David-

Another thought ? after posting my previous post, I remembered there was another area that presented a problem during the light instillation ? and that was the shape of the lens itself.

Apparently earlier versions of the light's lens were made from thin material because the initial lens shipped with the lighting kit was thin and somewhat flexible. However, the lens that came with the second wing light I ordered was at least twice as thick (think it is also used on the RV-10) ... anyway it is a whole lot stiffer. The thin lens conformed to the curvature of the leading edge like a glove with very little pressure applied. However, the thicker lens was not even close and could not be flexed by hand to fit ? either the bottom would sit flush with the skin or the top but not both. If memory serves me correctly, it was over bent from Van's.

I had to do quite a few cycles of heating the lens with a heat gun, relaxing the curve a little and letting it cool. Also used the leading edge of the wing to help form the lens as it cooled. Eventually, both the top and bottom of the lens was made to fit fairly snug to the curve of the leading edge. It was not as perfect of a fit as the thinner lens, but acceptable.

So assuming the holes in your lens backing strap matches the template perfectly (and drilled skin holes) and the wing skin has no bulges without the lens screwed in place, your bulge issue may very well be that the lens is NOT conforming to the curvature of the leading edge and not sitting flush on the wing skin BOTH above and below the light cutout ... as was my thicker lens before tweaking.

Hope this info and the good tips you received from others help you resolve the issue. Good luck and happy building,
 
John-G said:
David-

Another thought ? after posting my previous post, I remembered there was another area that presented a problem during the light instillation ? and that was the shape of the lens itself.

Apparently earlier versions of the light's lens were made from thin material because the initial lens shipped with the lighting kit was thin and somewhat flexible. However, the lens that came with the second wing light I ordered was at least twice as thick (think it is also used on the RV-10) ... anyway it is a whole lot stiffer. The thin lens conformed to the curvature of the leading edge like a glove with very little pressure applied. However, the thicker lens was not even close and could not be flexed by hand to fit ? either the bottom would sit flush with the skin or the top but not both. If memory serves me correctly, it was over bent from Van's.

I had to do quite a few cycles of heating the lens with a heat gun, relaxing the curve a little and letting it cool. Also used the leading edge of the wing to help form the lens as it cooled. Eventually, both the top and bottom of the lens was made to fit fairly snug to the curve of the leading edge. It was not as perfect of a fit as the thinner lens, but acceptable.

So assuming the holes in your lens backing strap matches the template perfectly (and drilled skin holes) and the wing skin has no bulges without the lens screwed in place, your bulge issue may very well be that the lens is NOT conforming to the curvature of the leading edge and not sitting flush on the wing skin BOTH above and below the light cutout ... as was my thicker lens before tweaking.

Hope this info and the good tips you received from others help you resolve the issue. Good luck and happy building,
Click to expand...

There must be a bit of variance with the bend. Mine seemed to be slightly under bent. I used a heat lamp to warm it while wedging it in place. It fits good top and bottom without distorting the skin, but there's a slight gap right at the front of the leading edge on both sides. A little silicone filled the gap just fine.

Jim
 
Follow up

thanks all, for your suggestions.

The dimples were too shallow because I didn't use the correct dimple die set. That's been corrected. I've trimmed the lens to the backing strips to minimize its size. The template was accurate with respect to the backing screws. Lastly, I very slightly filed some of the holes in the wing to allow the screws to start normal to the skin surface to reduce some of the pucker.

I'm still not happy at all with the way it's turned out. There's a good 1/4" gap between the leading edge of the lens and the skin. I didn't know about the trick of using heat to make the Lexan pliable enough to reshape to match the wing.

Does anyone else have this much gap? If not, I'll scrap this piece and start over with fresh Lexan and new backing strips.

-dbh

Leading%20Edge%20Gap.jpg
 
I just completed the landing light install and got similar results.:( The lens fits nicely along the top edge all the way through the leading edge curve but there is a gap of about 1/4" along the sides of the lower half of the lens. I think I will try to heat the lens in place and get it to conform correctly. That will require "slotting" the lower holes. I plan to fill the excess slotting with epoxy to get a tight fit for the screws. If that fails then I am going to try to form a new piece of lexan to the leading edge shape after heating in an oven. Stay tuned.:)
 
I have seen the edges of the hole in the wing stretched and distorted by too aggressive material removal with the tin snips, this looks like that.
 
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