Epoxy dent repair

[FlyingDude]

Guys,

This happened while dynamically balancing my prop. The washers chipped the cowl closing...

How do you fix that? Can I use the Bondo epoxy from Lowes? Thanks.

[ShuRugal]

Plenty of planes flying around with Bondo filling bird dents. Should be fine for filling a small chip in a non structural component.

Looks like a cosmetic repair to me, but I'm not an IA. Ask the A&P who was doing the balance and chipped it?

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[FlyingDude]

18 minutes ago, ShuRugal said:

Ask the A&P who was doing the balance and chipped it

He said, without me needing to ask, while he was showing me the dent, that "any epoxy resin will do". I wanted pireps before proceeding...

Thanks...

[ShuRugal]

In that case, I'd definitely go with the Bondo. It's specifically designed to provide a durable and paintable surface.

Personally, I'd be insisting the A&P make it right, but I don't know whether that's a fight worth fighting for you.

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[FlyingDude]

3 minutes ago, ShuRugal said:

that's a fight worth fighting for you

Not worth it. He was honest and pointed it out... Rather than having me discover it during next preflight... Or after it soaks water. I helped fix fiberglass boats. It's not hard. Just wanted to hear you guys' inputs, in case there's any gotcha...

[RLCarter]

Is the Bondo brand epoxy or regular fiberglass resin? Easy fix with either, just don’t use any body fillers, they won’t seal the cloth. Looks like the damage is into the cloth so it needs to be re-sealed before the cloth is contaminated with oil/grease etc…. 

[MB65E]

West systems 105 with 205/206 hardner epoxy and some micro. Honestly you could probably sand  and paint it.

-Matt

[FlyingDude]

1 hour ago, RLCarter said:

cloth so it needs to be re-sealed before

Could you explain? Doesn't the fiberglass epoxy seal it already? Thanks

[FlyingDude]

Bondo

https://www.lowes.com/pd/Bondo-32-fl-oz-Brown-Fiberglass-Resin-Repair/3371926

[RLCarter]

1 hour ago, FlyingDude said:

Could you explain? Doesn't the fiberglass epoxy seal it already? Thanks

Yes it will seal it, my post wasn’t very clear, sorry about that... My point was to fill the area with epoxy not body filler or spot fillers.. honestly I would use the 2 part 5 minute that comes in syringe and do multiple applications 

[TTaylor]

I think what most have been trying to say is to get good adhesion into the fiberglass you want a "wet"  the contact area using epoxy resin rather than just a dry filler like Bondo.  Actually looking at this any body filler would work.  What RLCarter is suggesting would also work, but will be a little more difficult to paint  because primer does not adhere to to straight epoxy as well as to a filler or a epoxy mixed with micro balloons or cotton flock. 

This is small enough that you are likely best to use any body filler. If you don't have supplies on your shelf, Bondo Glazing and Spot Putty would work.  The polyester based products will work much quicker (30 minutes curing) than trying to use epoxy based products  (24 hours curing time). 

I keep epoxy, micro balloons and flock on my shelf so that is what I would use, but they are not as easy to acquire as polyester body filler. 

Make sure you clean the area well, sand back on the edges slightly to feather the area.  Wipe it with acetone or 91% isopropyl alcohol and let dry a few minutes before applying the filler. Make sure the filler goes on damp enough to "wet" into the fiberglass and make good contact and adhesion. 

Prime and paint after with touch up paint and you will never see it.

 

 

 

 

[M20F-1968]

You have an E model which usually comes with an aluminum cowling.  But, the damaged part looks to be fiberglass.  Likely it is polyester resin fiberglass and the best fix would be to use Epoxy resin and fiberglass cloth.  Sand the are well, cut up the fiberglass cloth, mix it with the epoxy resin mixed with the hardener as per instructions, and use the slurry to fill the hole.  Then, use a couple of pieces to fiberglass cloth and the mixed resin to patch over the top of the damaged are and onto the cowling by about 1/2 overlap on all sides.  All areas where the fiberglass must adhere must be clean and sanded of all paint.

If the damaged part is aluminum, use an aerospace body filler.

All can be painted when dry.

John Breda

[M20F-1968]

You have an E model which usually comes with an aluminum cowling.  But, the damaged part looks to be fiberglass.  Likely it is polyester resin fiberglass and the best fix would be to use Epoxy resin and fiberglass cloth.  Sand the area well so it is clean and roughened up, with a sanded overlap area of at least 1/2" around the damaged area.  Cut up the fiberglass cloth, mix it with the epoxy resin mixed with the hardener as per instructions, and use the slurry to fill the hole. 

Use a couple of pieces to fiberglass cloth and the mixed resin to patch over the top of the damaged are and onto the cowling by about 1/2 overlap on all sides.  All areas where the fiberglass must adhere must be clean and sanded of all paint.

Your damaged area is very close to the edge, and you will likely need to curl the new fiberglass around the edge.  Wetted fiberglass does not want to bend 90 degrees or more.  I have sometimes taken off the part, hung it up and allowed the wetted fiberglass to bend on its ow with the help of gravity.  Be creative, it is not rocket science, you just need the fiberglass to stick to a clean, roughened surface without air bubbles beneath the new piece. 

If the damaged part is aluminum, use an aerospace body filler.

All can be painted when dry.

John Breda

[jetdriven]

If that’s in a fiberglass part you’re wanting to fill it, you can do this easily with West systems Epoxy and microballoons. That stuff is really tenacious and it’s flexible without cracking. I’ve use the stuff pretty extensively there’s a lot of it on my plane but you can’t tell where it is because it doesn’t crack.

[Yooper Rocketman]

Where are you at in Michigan?  I fly down to lower Michigan regularly and have all the stuff to fix that properly.  I also have a few hours working on composite planes.

Tom

 

[N201MKTurbo]

You could read the fiberglass repair section in 43-13,1B. It has everything you want to know.

It would be fine if you did nothing.

[Guest]

That appears to be part of an ARI cowl closure so it’s not structural.  Fill it with a slurry of epoxy resin and microballoons, sand to the correct shape and touch up the paint.

It will take longer to talk about it than actually doing it.

Clarence

[hammdo]

M20Doc has a great point. I'd fill/sand and If I needed a patch, I'd use a 2 ply bid tape and stipple it in 'after' the fill sand has cured. Use peelply over the tape and primer/paint as necessary after the tape cures. Peelply keeps things nice and can prevent those 'needles' in cured bid layups. . 

-Don

[carusoam]

Dude!

Now you have done it…

You have received all of the info you need to get that thing fixed… from some pretty talented MSers…

+ you got an awesome invite to pick up some additional experience regarding planes using composites… nearby in the UP…

Tom’s plane uses a fair amount of composites… and it goes wicked fast… 

Go visit if able.

Best regards,

-a-

 

 

[0TreeLemur]

Our C looks like that from previous owner letting the engine mounts get so old that they sagged and the prop flange rubbed against the guppy mouth closure.   I hit it with some touch up paint.  That was a couple of years ago after replacing the motor mounts.  Still good.

[A64Pilot]

On 9/28/2021 at 10:12 AM, MB65E said:

West systems 105 with 205/206 hardner epoxy and some micro. Honestly you could probably sand  and paint it.

-Matt

Bondo will work, the above is a better repair though, and since you say you have experience fixing fiberglass boats go for it.

Now if you had experience fixing car bodies with Bondo, then go that route. It’s just cosmetic, but the West systems will have less chance of falling out in the future 

[Yetti]

I would probably just go for JB weld with aluminum foil to form it. JB Weld seems to be expoy with some aluminum added.  Sand and paint. 1/2 hour fix.

[N201MKTurbo]

2 hours ago, Yetti said:

I would probably just go for JB weld with aluminum foil to form it. JB Weld seems to be expoy with some aluminum added.  Sand and paint. 1/2 hour fix.

JB weld would be better than Bondo. Bondo is polyester based. You really need epoxy based. 
 

JB weld is just 1 to 1 epoxy, cabosil and aluminum powder. Not a bad choice.

[Andy95W]

I had the exact same damage on my cowl closure before I fixed my engine sag.

I fixed it with JB Weld.  One of these days I’ll get around to sanding and painting it.

[Yetti]

I switched I think I would use a couple of strips of black electrical tape on either side to make a little channel so the JB weld does not run down and have less to sand.