4 pl carbon fiber nose bowl

[Wes Helm Bearhawk 1209]

Best way to fasten nut plates to hold the two piece carbon fiber nose bowl together. Will setting rivets damage the carbon fiber? First time working with carbon fiber. By the way its one of Bob's nose bowls. Any help would be appreciated thanks wes

[zkelley2]

Use the AN470A instead of the AD rivets, at least for fiberglass. Someone else can chime in if there's corrosion issues with aluminum rivets through carbon. If there was I'd imagine you'd catch it before it actually became a problem, on the other hand they might only last a couple months.

[jaredyates]

With fiberglass I always made sure the composite was sandwiched between two layers of metal. Seems like worthwhile insurance for carbon too. In the case of the nose bowl split, the outer part of the sandwich would be a wide washer and the inner part would be a narrow strip holding the nutplates.

[svyolo]

I agree, you need a lot of bearing surface. Holes in fiberglass abrade away very quickly without it, and I think carbon is probably worse. Tinnerman washers work well.

[Bcone1381]

How do you treat rivets that secure a nut plate? Do they get sandwiched too?

[Glenn Patterson]

Our solution to hold the two halves was to rivet K1000 nut plates to an aluminum backer strip & bond it the backside of the lower half. The strip will act like a backing washer and be able to take the forces of the screws going in and out to secure the top. Drill holes in the hacking plate on the side to be glued so that the adhesive will come through in a rivet fashion. Use the truss head screws with nylon washers under the screw heads. The nylon screws save wear on the paint and cowl.

[AKKen07]

I suppose permanently fiberglassing the two parts together would be problematic eh? I’m nowhere near that stage but seems like something I would consider if the Mx headache wasn’t excessive...

[zkelley2]

You really really want the nosebowl to be 2 pieces. Theres no issue putting nutplates and rivets into fiberglass.

[jaredyates]

Any time you want to remove the cowl, you'd either have to remove the prop, or separate the nosebowl from the rest of the cowl. And you wouldn't be able to run the engine uncowled for mx runs, etc.

[svyolo]

I was questioning the rivets in the fiberglass nose bowl as well. Long term they don't loosen up in their holes?

[AKKen07]

Gotcha, thx!