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Fiberglass Advice Needed

tom_AZ

Well Known Member
I need to make a repair to the forward portion of my nose wheel pant (explanation below, if interested). I’ve done a little bit of fiberglass work, but essentially just simple stuff—repairing cracks, etc… Now I have a hole, roughly 1.5 x 2”, right at the front. Fortunately, I was able to borrow an analogous wheel pant from a friend who is in the middle of his C.I. and have made molds from that, both on the inside and outside to help re-establish the shape.

Two questions:

1) Thoughts as to whether it’s best to glass the inside or outside first? My instinct is to secure the “inside” mold into my damaged wheel pant and lay down the first layer or two of glass-impregnated bi-directional cloth on the outside. After curing and removal of the mold, I’d follow that with additional layers inside and out. The advantage would seem to be ensuring that there is enough additional depth needed over the hole to get a reasonable thickness of glass w/o altering the external shape. The disadvantage would seem to be a little more challenge to achieving that external shape through sanding.

2) I don’t have any release film to cover the mold(s), and would like to get on this quickly with minimal fuss. What are reasonable alternatives, e.g. does fiberglass stick to plastic kitchen (cling) wrap? I’m not that worried about small wrinkles/imperfections as I should only need the mold for the first layer.

If you’re wondering how I came to need this advice, the damage happened as I was putting the airplane away yesterday. As the mains went over the steel tracks that guide the sliding hangar doors, the nosewheel jumped the “shoe” that I’d fabricated for the Airtug and the wheel pant impacted the vertical steel plate that would typically serve as the stop for a non-panted tire. I’ve been using this modified Airtug for 3-4 years w/o problems, but recently moved to a different hangar and the tracks are quite a bit higher in this one. I can only make the shoe slightly higher w/o it touching the bottom of the wheel pants, but my plan is to tweak that. I’m also going to use some thin plywood or similar to make the approach to the tracks more gradual.
 
Scarf

I recommend reading Dan's Sticky in the fiberglass section.
My preference is heavy packing tape. Strips will conform to most curves. A couple coats of carnuba wax before use and nothing sticks. Irregularites won't matter on the inside mold.
Sand the scarf first. Sand the inside clean.
Wipe surfaces with a solvent to thoroughly clean.
I prefer to layup the outer shape first with two or three layers.
Tape the mold to the inside.
First layer is a tiny bit larger than the size of the hole then progressively larger to the diameter of the scarf.
After curing, then inside just gets filled in the same way. Small patch up to largest.
 
As you have made molds consider making a brand new nose cone. I made a stronger modified shape nose cone for my 9A with more ground clearance by laying up the new cone inside the mold. Yours would be more straightforward as the RV10 does not need extra ground clearance under the nose cone.

Fin 9A
 
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Have you considered buying the front portion of the nose wheel pant from Van’s? They might sell it.
 
Thanks

Thanks all.

I may give the packing tape/wax a try, seems like a good idea. Thanks too for confirmation that glassing the outside first seems best to you as well.

I've read through Dan's sticky--all good stuff, but more about fabrication than repair.

I'm ready for surface prep--a combination of sandpaper and a roloc/grinder.

My mold only fills the first couple of inches in the front of the pant, so making a new one isn't an option with what I have at this point. Making a full mold, or just buying one from Van's, if available, is certainly a consideration if for some reason the repair doesn't go well, but will try the repair path first. It's the journey, not the destination... :)
 
Wax Buff 5 times - carnauba works well.

If you wax the mold then do it 5 times and buff in between. The last coatings should buff easily, apply at right angles on alternate applications. This has served me well in my work. A couple of wax applications was goo about 80% of the time and the one that stuck to my mold was scary. I had 100 hrs invested in the mold construction.
 
I had a hole in the nose cone too, as well as a couple of matching cracks at the wheel well. I glassed in some thin fiberglass on the back side, sanded off the gelcoat on the outside with a 2" random orbital with fiber surface prep discs as well as an oscillating saw with sanding pad. Then 2 or 3 layers of 7781 fiberglass on the outside of each repair, each layer a little larger. After filling/finishing I took them into the local body shop to get painted. I also did repairs to the main gear pants. It was a PITA but the end result was fine.

..
 

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