Another delamination problem
|
Hey guys. I have a spot on the main wing of my Q2 where the fiberglass has delamed from the foam. Probably a spot about the diameter of a baseball. No apparent damage to the fiberglass and I can't feel any indentions on the foam but I can tell the two have separated. Suggestions on how to repair?
|
|
|
|
Photos. Come on guys, please supply photos. While you're at it, do a tap test and outline the perimeter of the damage with bits of tape so we can envision the extent. Sam On Sun, Jun 26, 2022 at 4:19 PM Nick Wright <nwright27@...> wrote: Hey guys. I have a spot on the main wing of my Q2 where the fiberglass has delamed from the foam. Probably a spot about the diameter of a baseball. No apparent damage to the fiberglass and I can't feel any indentions on the foam but I can tell the two have separated. Suggestions on how to repair? |
|
|
|
Rick Hole
You must do the tap test. The delam will be larger than what you can feel. I have done similar repairs oodles of times in my Velocity days. I have done repairs both by syringe injection and by cutting out the glass around the delam, building up the crushed foam and reglassing. If the foam is crushed, just filling the void with epoxy, weighing down the glass above will not be sufficient. It would be something like painting over rust, it'll look ok for a while then you get to do it over. By the way, it is not all that difficult a repair. Have fun! Rick Hole _._,_._,_ |
|
|
 |
|
|
|
Please send another photo, so we can see where this is located on the wing (ie. zoom out). Some places you repair can be very critical and others, not so much, so we need to see where this is located. Jay |
|
|
|
Jay, I am away from my airplane for a couple days. I will post a picture when I get home. The spot is about 12 inches from the wing root on the LE.
|
|
|
|
Thanks. The picture will still help, but that location is one you need to be sure about. The closer to the wing root, the more bending stress on the wing, so the more critical the repair.
Cheers, Jay |
|
|
|
Here is a zoomed out picture. I did a tap test and the center of the of the damaged area does has a different sound.
 |
|
|
|
That location looks like it was damaged by a glancing impact. It will require some careful repair work because it is near the high stress portion of the spar caps. Before you start, completely read and understand the repair related portions in the linked document below. Then we can help walk you through the steps.
toggle quoted message
Show quoted text
http://n8wq.scheevel.com/documents/RAF_composite_education_section_from_Q2Plans.pdf Cheers, Jay On Jun 30, 2022, at 3:44 PM, Nick Wright <nwright27@...> wrote:
|
|
|
|
I will print these off tomorrow at work Jay. Thanks so much for your input. Sent you a PM on Facebook also!
|
|
|
|
Rick Hole
I use a quarter coin held between thumb and index finger. Tap the edge of the coin lightly and note the sound. For orientation go outboard from the damaged area a foot or two for some test taps against solid glass-to-foam sound. It will be noticeably duller than the sound at the center of the delamination. Tap around that area and mark where the taps sound the same as your test taps. The area will always be larger than the visible delam area. If you are using the injection repair technique drill your holes at the edge of the area you have marked. You may need more than two holes if the area is large. When the area has been filled and epoxy flows form the opposite hole (the higher one) weigh down the delam area with something heavy to compress the fiberglass skin against the foam and push the excess epoxy out through the holes.
Note that if before flooding you should be able to push the delam fiberglass against solid foam. If the area is mushy that indicates the foam is crushed. In that case it is better to cut the skin where you have marked (a bit bigger is better), remove the damaged foam and build back with a contoured piece of foam of the same type, glued with epoxy mixed with micro-balloons, when cured, sand and glass on a replacement patch. Q2 instructions have a chapter how to do this.
Use of two-part foam is not acceptable as it is not strong enough to carry the load.
If you can find an experienced fiberglass builder to advise you in person, that is your best course.
Rick Hole
_ |
|
|
|
Thanks for the link Jay and input Rick. I assume syringes like the West Marine injection syringes are adequate? I'm looking to get this repaired soon.
|
|
|
|
If it were my wing, I would remove the damaged portion and inspect the foam, then replace with new foam of the same type, then reshape the foam and do the proper feathering of glass to effectively “renew” the structure. You can’t verify what you cant see, and injecting epoxy is that type of repair.
Cheers, Jay
From: main@Q-List.groups.io <main@Q-List.groups.io> On Behalf Of Nick Wright
Sent: Monday, July 4, 2022 6:03 AM To: main@Q-List.groups.io Subject: Re: [Q-List] Another delamination problem
Thanks for the link Jay and input Rick. I assume syringes like the West Marine injection syringes are adequate? I'm looking to get this repaired soon. |
|
|
|
Nick, If you haven't already made your repair, consider doing a little more investigating work. One thing you can easily do is determine where your damage is in relation to the underlying structure. Get a dry erase marker and a set of the wing layup plans. Then, best as you can, draw the layups outline directly onto the wing. You will then be able to see if your damage has affected the underlying structure. (Be sure to try the marker on a unobtrusive part of the airframe to make sure it doesn't soak in.)
Something else, you might want to consider. When you do, tap tests, use the dry erase marker, or even little bits of tape, and mark the outside edge of where you detect the damage. You will then get a visual of what's underneath.
Be very careful, especially in this high heat, of exothermic reaction if you are doing the injection method when you mix up some epoxy and micro. It is highly insulated and can kick. If you have an exothermic event it will wind up destroying more of the foam. Use slow curing hardener and get a couple of bags of frozen peas to lay over the area to keep it cool. Way back when, I had a mysterious "dent" in the upper skin and flew it like that for a couple of years, before I decided to just go ahead and replace the wing. In fact, we cut the foam cores at the Spring Fling. When I build the new wing, I added one more uni ply, just because I had started racing. Several years ago, I did a repair to my canard. Not the same damage or location, but I thought you might be interested in seeing how I handled it. You can also see what I did with the layup replacement following Rutan's repair section in the education section of the plans. It's not the same damage as yours, so I'll just call it an FYI. Lots of pictures... https://q-list.groups.io/g/main/files/Repairing%20a%20canard%20crunch.pdf And like Rick Hole said, see if you can find some someone who is experienced in composites. They will they should be a big help. Sam  |
|
|
|
One more diagram while determining damage.
 |
|
|
|
And one last thing I wanted to mention. Way back when, we had a double fatality due to a bad wing repair. My memory is sketchy, but I think that one of the Quickie dealers had a broken wing due to ground handling or something. They contacted QAC and were instructed how to repair the wing. I think they used pour in foam, and my guess was it was a pretty big repair. They got it back in the air, but on a subsequent flight they got into some big turbulence and the wing failed at the repair.
Just a word of caution. Sam |
|
|
|
Just to reinforce, what Sam has said. The upper skin and spar caps, both in compression when loaded, are more likely to fail than the bottom skin/spar, which are in tension. The things that keep the upper surface from failing are: 1. good straight fiber orientation, 2. no undulations in the surface, 3. good bond of the skin/spar-caps to the underlying foam, and 4. good continuous foam/micro beneath the layup.
It is not hard to do these things, but cutting corners, or getting in a hurry is not helpful, so take your time and do it right. Also get someone who is experienced to advise you prior and have them look over your work when you are done.
BTW, on your photo of damaged section, I suspect the horizontal breaks in paint that extend out from the more rounded area may correspond to the edges of one or more of the spar caps that Sam outlined on his wing repair photo. This would explain their orientation.
Cheers, Jay
From: main@Q-List.groups.io <main@Q-List.groups.io> On Behalf Of Sam Hoskins
Sent: Wednesday, July 6, 2022 10:21 AM To: main@Q-List.groups.io Subject: Re: [Q-List] Another delamination problem
And one last thing I wanted to mention. Way back when, we had a double fatality due to a bad wing repair. My memory is sketchy, but I think that one of the Quickie dealers had a broken wing due to ground handling or something. They contacted QAC and were instructed how to repair the wing. I think they used pour in foam, and my guess was it was a pretty big repair. They got it back in the air, but on a subsequent flight they got into some big turbulence and the wing failed at the repair. |
|
|
|
Standard in the repair is a "100%" scarf of the original skins. So the idea is no thick hard edges..which then become stress risers, especially in compression. The 100% scarf repair is also depicted in wood skin structure. AC-43.13B. Bevel the edge around
your repair area skin in other words, think oval or round circle..never square.
If this were my aircraft I would have already planned on removing that skin area, refoam, and re-skin because the chance of foam compression under whatever impact was done appears to be enough to be worrysome. Be very careful not to cut into the spar caps.
Jay is correct too that the loading is ever increasing as the surface reaches the fuselage junction. This damage is not very far out on the span. Done correctly this repair is perfectly sound. Follow the same ply schedule as the original surface was built
with. Where is the aircraft located now? I am hoping an experienced plastic geek is nearby for you to lean on during the work if your not comfortable solo.
Regards.
Vern
From: main@Q-List.groups.io <main@Q-List.groups.io> on behalf of Jay Scheevel <jay@...>
Sent: Wednesday, July 6, 2022 11:36 AM To: main@Q-List.groups.io <main@Q-List.groups.io> Subject: Re: [Q-List] Another delamination problem Just to reinforce, what Sam has said. The upper skin and spar caps, both in compression when loaded, are more likely to fail than the bottom skin/spar, which are in tension. The things that keep the upper surface from failing are: 1. good straight fiber orientation, 2. no undulations in the surface, 3. good bond of the skin/spar-caps to the underlying foam, and 4. good continuous foam/micro beneath the layup.
It is not hard to do these things, but cutting corners, or getting in a hurry is not helpful, so take your time and do it right. Also get someone who is experienced to advise you prior and have them look over your work when you are done.
BTW, on your photo of damaged section, I suspect the horizontal breaks in paint that extend out from the more rounded area may correspond to the edges of one or more of the spar caps that Sam outlined on his wing repair photo. This would explain their orientation.
Cheers, Jay
From: main@Q-List.groups.io <main@Q-List.groups.io>
On Behalf Of Sam Hoskins
And one last thing I wanted to mention. Way back when, we had a double fatality due to a bad wing repair. My memory is sketchy, but I think that one of the Quickie dealers had a broken wing due to ground handling or something. They contacted
QAC and were instructed how to repair the wing. I think they used pour in foam, and my guess was it was a pretty big repair. They got it back in the air, but on a subsequent flight they got into some big turbulence and the wing failed at the repair. |
|
|
|
Thanks everyone for responding. I was thinking MAYBE I could inject but it sounds like removing the old glass is the way to go. I'm comfortable with the injection method but the other I may need some backup on. Airplane is located in South Georgia (KCXU).
|
|
|
|
Also Sam my damage is on the LE between layers H and I. I read the article of your repair once and probably will be reviewing multiple times this week.
|
|
|
