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RV6 Cowl attachment just aft of the spinner

Inhot

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I have an older Rv6 (completed 1990). The cowl attachments just aft of the spinner utilize hinges. Several eyelets/barrels/lugs (whatever) of the lower hinge pieces have failed.

From my reading on this forum I have learned the original -6 plans called for a short length of MS-2001-4 hinge behind the spinner.

Apparently this heavier hinge was subject to cracking, which caused Vans to change the design and specify for the cowling to be held together at the front by an aluminum strip, riveted to one half and screwed to the other.

My question, as a non-builder, once the aluminum and the nutplates are riveted in place is the procedure to then embed them in fiberglass? Inquiring minds want to know. 😊

Thanks,
Mike
 
Not sure what your asking. But I would scuf the surface of the aluminum with 180 sand paper. Clean with denatured alcohol. Alodine rinse with water, blow dry it and using flox on the mating surface. Just a skim coat, then rivet it wet. Afterwhitch if you don’t think that’s strong enough. Go ahead and glass over it by at least 1 inch all round. Just a couple layers would be safishent be shure to overlap by 1 inch. Vacuum bag if you can. No need to sand backside. U.V. protect it. And your done.

RD
 
Thank you for your response, it's what I was looking for. However, I am not familiar with the term "flox." Could you elaborate?
 
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Flox is epoxy mixed with a filler. Geary strong. It’s used to assemble composite parts etc.. you can use just about anything depending on what it’s for. For your application I would just cut up some of the glass cloth. I just hold the cloth in the palm of my hand and using a sizers repeatedly cut the small piece of cloth tile it’s just a bunch of fuzz. Then mix your epoxy and then add the fuzz. Mix well, and apply. You can use it to fill the old holes to. Just use a q tip to push it in the hole. Or you can buy caboseal, or use micro Balloons.

RD
 
You can buy flox from aircraft spruce. Generally flox is consider structural and micro more for sanding/filling
 
Similar to this?

Ok, I'm with you now. Flox appears to serve the same purpose as West 404 high density adhesive filler.
 

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Ok, I'm with you now. Flox appears to serve the same purpose as West 404 high density adhesive filler.

I would not make that assumption based on what I could find online about 404. You're not looking for a filler, you're looking for fibers. Flox is the most commonly used one of those.
 
I think we might be splitting hairs. Spruce describes flox as: "A structural resin filler." West 404, also an adhesive filler, is recommended for "hardware bonding requiring a strong interface between dissimilar materials."
I appreciate the feedback. Thank you.
 
I think we might be splitting hairs. Spruce describes flox as: "A structural resin filler." West 404, also an adhesive filler, is recommended for "hardware bonding requiring a strong interface between dissimilar materials."
I appreciate the feedback. Thank you.

Bonding<>Something that gives structural strength to the material.

If you're looking for something out of the West catalog, you're looking for 403, not 404.

https://www.westsystem.com/403-microfibers/
 
Ring Gear Interference

Suggest that none of your new nutplates line up with the ring gear.
I had one screw that was always hard to remove; I had to replace it regularly.
Turns out that it was getting peened over by the ring gear when the engine shook on its mounts.
 
I have an older Rv6 (completed 1990). The cowl attachments just aft of the spinner utilize hinges. Several eyelets/barrels/lugs (whatever) of the lower hinge pieces have failed.

From my reading on this forum I have learned the original -6 plans called for a short length of MS-2001-4 hinge behind the spinner.

Apparently this heavier hinge was subject to cracking, which caused Vans to change the design and specify for the cowling to be held together at the front by an aluminum strip, riveted to one half and screwed to the other.

My question, as a non-builder, once the aluminum and the nutplates are riveted in place is the procedure to then embed them in fiberglass? Inquiring minds want to know. 😊

Thanks,
Mike

Very interested into know if this modification provides a lasting solution. I too have a 6 built with short lengths of hinge beside the spinner, which failed, were replaced and failed again.

My fixed pitch prop is dynamically balanced and there is no interference with baffles or other parts.

I experimented by replacing the hinges with two pieces of sheet aluminium each with 6 nutplates aligned with the holes left by the hinges. Both failed within a few hours, leading me to wonder if my next move should be to fabricate stronger plates or replicate the overlapping fibreglass join that is now standard? Although fibreglass clearly works, it does sound a bit counterintuitive for a join that appears to be subject to enough movement or vibration to fail the metal parts.
 
Fiberglass tab

with 2 or 3 nut plates #8 screws is a solution that works. I had hinge method, replaced with aluminum... both failed in short order.

Take top cowl and put tape down as a release agent in both left and right areas where the joint/seam will be.

Set cowl up on floor, firewall side down, connect cowl halves together with top bottom hinge pins. Now lay up two or three layers of glass/ resin 4x4 , or whatever size seems appropriate on plastic/ tin foil etc

Take layup over to set up cowl and reach in and apply , essentially glassing the cowl together in the area where previous hinge/plate were that failed.

After proper set up time separate cowl halves ( tape keeps the lay up from sticking to top cowl , but not lower half.

Mount the cowl......and drill through top cowl through newly created tab. Cleco together , and add nut plates. Sand and trim your mounting tabs as needed. I use two screws each side, some use 3...

This is how newer kits are in this area. One day job for a rookie like me. PERFECT FIT TOO....

GOOD LUCK
 
Sounds Good!

I appreciate your response. Looks like that may well be the way to go. Couple of questions. What's the approximate thickness of the fibreglass tab you created and far above the bottom cowl does it extend? How many hours on the plane since the repair?
Thanks,
Mike
 
Thin

I cannot comment on thickness, but can say 4 layers. I just purchased a Bondo brand repair kit from Lowe’s or Home Depot. It extends up to where ever you want. Mine is likely 2.5-3.5 inches . Just give yourself adequate edge distance for your nut plates in the tab u create and the overlap from top cowl area. I used the nut plates to get an idea. Make bigger, easy to cut grind down to your final need/look. I tossed my pics of mine. Look on line for others more recent builds in this area to get a visual as to placement. Zoom in here and u can get an idea of my height screw spacing. Over 100 hrs sine complete... no issues. FYI this is how all more recent cowls are constructed. Btw, your cowl is constructed with polyester resin being a 1990’s vintage, so no issues with any resin system u use. My RV is 1990 kit . Cheers
 

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See if you can get a look at a later cowl off a 6,7,8,9,10,14 You will see how later versions got away from those problematic hinge fasteners.
 
Will Do

Appreciate guys. Thanks Butch for the elaboration. I'm going to tackle it this week.
 
Thanks for the advice and instructions Butch, I’m another who’ll be implementing this mod when I get an opportunity. Good luck with it Mike, let us know how it goes.
 
Chickened out

My local A&P was not entusiastic about the fiberglass tab concept. He talked me into using an aluminum plate that has been fiberglassed and riveted in place. The weather hasn't cooperated since the repair, so I cannot comment on the reliability yet. I'll put some hours on it and let you know how it holds up.
 
A&P was wrong

The aluminum plate my A&P recommended failed after about ten hours. I subsequently reverted to the recommended overlapping fiberglass tabs. It has held up now for over 100 hours
 
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