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Todd
11-13-2011, 01:36 PM
I've been trying to use nutplates for everything and avoid Tinnermans and sheet metal screws. When installing my new Cub Doctor instrument panel, there's no clean way to fasten the boot cowl to the corrugations along the edge. I came a cross a product that is a real problem solver for certain situations like this one - bonded nutplates. They are floating nutplates held to the substrate by two-part methacrylate adhesive instead of rivets. They include a rubber "worm" that holds the nutplate in place while the adhesive sets and also prevents glue from getting into the threads or inhibiting the floating action of the nut. Very slick!

rocket
11-13-2011, 04:49 PM
Tod,
the 100 dollar answer is?

I think the only real problem would the unsuspecting mechanic breaking one of these off and not understanding the nature of the fastener might loose it in a place that could cause some trauma afterward, say in a control or worse sitting on top of a circuit breaker making some smoke during a critical phase of flight.

I know a little paranoid but that is just how my mind works

Rocket

smcnutt
11-14-2011, 11:19 AM
Very nice. Thanks for the info!

mike mcs repair
11-14-2011, 12:49 PM
Tod,
the 100 dollar answer is?

I think the only real problem would the unsuspecting mechanic breaking one of these off and not understanding the nature of the fastener might loose it in a place that could cause some trauma afterward, say in a control or worse sitting on top of a circuit breaker making some smoke during a critical phase of flight.

I know a little paranoid but that is just how my mind works

Rocket

ya was thinking the same.... zzzzap!
I always just (pop)/rivet nut plates on for that application...

guess i just don't trust bonded stuff.... will it still be there 60 years from now, like the rest of our plane parts.....

Curly
11-14-2011, 04:25 PM
"guess i just don't trust bonded stuff"

35 odd years ago I bonded two pieces of aluminium together using common old Araldite - it's still ok.

Metal to metal bonding has all but replaced spot welding in many applications. (l once lost one of my best customers when he changed from spotwelding to bonding - it was hard to argue with a $150000 yearly production cost saving). The French motor vehicle Peugeot has been bonding many of its panels for the last 20 years and if your car is less than 15 years old you are driving behind a windscreen that is bonded in with adhesive. I am sure Boeing would not use "glue" if rivets were better but they use it extensively.

Have a read of the literature on modern adhesives - I think it will allay any fears that "things will fall off" if fastened with "glue".

Throttle Pusher
11-14-2011, 07:02 PM
ScareBus I mean AirBus bonds the stringers to the skin on their airplanes, My main question would not be, if it falls off, rather how do I remove and replace when one strips-out?

Gilbert Pierce
11-14-2011, 07:29 PM
All those VG's uyou guys use are put on with Loctite Depend 330 Adhesive

MN_flyer1
11-14-2011, 07:31 PM
The doors on vehicles have been glued on for years. Can't image much more stress than that especially where my kids are involved. :)

Todd
11-14-2011, 10:21 PM
I build offshore sailboats for a living and we use a lot of adhesive products like this in place of, or sometimes in addition to highly loaded fasteners. At any rate, I did testing on it before I tried these nutplates and was suitably impressed. If it ever needs to come apart, carefully applied heat would do the job, but it might scorch the paint too. The only thing I couldn't test was the passage of time on the bond strength. Regarding the potential hazards, I agree that losing anything metallic behind the instrument panel is hazardous. The fasteners holding the central cover in place will be occasionally removed, but it will be very obvious when removing them if a nutplate is loose. The others will be torqued up once and forgotten like all the other nutplates, riveted or glued in. It's the same hazard as losing a screw down there. Better find it!

rocket
11-14-2011, 11:14 PM
Hmmm. Once upon a time I worked at TIMCO at their composite repair facility in NC and then Tramco at Pain Field (later BFG aerospace) doing the same: metal bond on the older boeings to 350deg hot bonds/autoclave on the all carbon control surfaces.

I would have loved to build big sail boats, say a carbon catamaran!!!! I had a little H-16 when I lived on the beach in Mukeltio.

Any way, the loads imposed by the unsuspecting ( read meathead ham-fisted) A&P on said nut plates would be problematic especially when one considers the condition of the substrate being bonded to. I guess those little DR(3/32 CS pop) rivets could not be any better and I hate them; i use solid 426 AD only.

All this being said I suppose I would like to see one of the glue on nut-plates in action before being completely against the idea and of course noted in some ones SRM or the next version of 43.13 as approved ...


Rocket

Nathan Hiebert
11-15-2011, 01:16 PM
I use the click-bond nutplates at work. These nutplates work great in tight places. Just like some of the others have said, you need to find the right type of glue to hold them in place. On the SkyCatchers (nutplate attached to a composite cowling), we used to use 9309 but they kept popping off so we changed to a different type of epoxy. On the Corvalis (granted it composite) we use plastic weld. The plastic weld works awesome on both aluminum and composite. When you bond them in place, make sure to scuff both the nutplate and adjacent surface for a solid bond.

Steve Pierce
11-19-2011, 09:06 AM
Slick product. I have dimpled and riveted nut plate in the corrugations with no problems but this looks like a great alternative.

Norman
11-19-2011, 04:41 PM
I work on Dash8's and we use those bonded anchor nuts on the bulkheads for installation of the prop spiner. They are a pain in the rear end! They are for ever being pushed off by ham fisted mechanics who always want to push on the screw with too much force. The glue is not strong enough for constant removal and intallation. I wish they would go back to being riveted on. It is a lot easier to replace a rivet than to wait for glue to dry and you just know its going to fall off again. What a pain!

nicka
11-27-2011, 02:58 PM
I use these nutplates all the time at work to replace wing fairing screws in pressurized turbo props, and they work just fine. They are no easier to break than a floating nutplate held on w/ little 3/32 rivets. Hamfisted is hamfisted, if your hell bent to break something then odds are there will be something to break.