Camloc / Skybolt style fasteners

B Cunningham · #1 01-28-2010, 04:03 PM

For my cowling installation instead of using skybolt style 1/4 turn fasteners in the typical manner, I chose to use #8 stainless screws and nut plates, with standard hinges along the horizontal sides. I am thinking about using skybolt style fasteners now and my question is, Will these style fasteners fit within the drilled holes I already have for the nutplates? Is there a way to remove my nutplates and make this transition?

flion · #2 01-28-2010, 05:49 PM

I can only speak for certain about the Milspec product, though I think the others are similar. Assuming the spacing works (and you can download the instructions from their website), then the holes will not be a problem because you will have to drill them out. Milspec supplies a jig for the drilling, so even if you need to offset from the original hole for edge distance, it shouldn't be a big problem. I'd be willing to bet that even if the spacings were wildly different you could still fill the screw holes and re-drill for the installation grommets without sacrificing strength. Likewise, since the receptacles are installed on an aluminum strip, I don't think there'd be a problem reworking the attachments for the nutplates.

B Cunningham · #3 01-28-2010, 07:30 PM

Patrick,
The Milspec website was helpful. Looks like the 4000 series fastener uses 1 inch spacing on the rivet holes for the receptacle. Since I already have an aluminum strip installed with nut plates, I was hoping that I could just drill out the nut plates without messing up the strip. Pretty sure I could only do that if the nut plate spacing is 1 inch also. Not sure... I cant see replacing the existing aluminum strip since I have already riveted it across the forward canopy deck skin. Cant really fill holes -- not working with fiberglass here.

Radomir · #4 01-28-2010, 09:26 PM

It's apples and oranges.. For example -- where you now have just a screw hole in the cowl itself.. well, that hole would have to be enlarged to about 1/2" in diameter.. These are HUGE holes in comparison to screws and nutplates.. The Al strip would also have huge hole.. forgot diameter.. but it doesn't even compare.. it's something like 3/4" or so...

boom3 · #5 01-28-2010, 10:00 PM

What don't you like about the screws? I'm still on the fence for my method of top cowl attachment.

Noah · #6 01-29-2010, 11:29 AM

Quote:

Originally Posted by boom3

What don't you like about the screws? I'm still on the fence for my method of top cowl attachment.

Well, I'm not the thread originator, but I'll hazard a guess. The speed with which you can remove the cowl will directly affect safety. Here's how. Lets say you are on a long cross country and you make a fuel stop. You will be much more likely to pull your cowl (at least the upper cowl) if it can be done quickly. I can pull my camloc-equipped upper cowl in under a minute. With screws, probably 7 minutes, depending on whether you use an electric screwdriver (which you're not likely to have to save weight). The idea is that the easier it is to pull the cowl, the more often you will do it, and the more likely you will be to catch a small problem from becoming a big problem. Like a missing nut on your exhaust stack, or a loose fuel line fitting with a small weeping fuel leak dripping near your exhaust - you get the idea.

As far as changing from nutplates to camlocs, I think you may need to replace your aluminum backing strips on your airframe, which is not that difficult to do, just need to drill out a few dozen rivets. The holes in the cowl get bigger so no problem there.

You will like the camlocs!

RV8R999 · #7 01-29-2010, 12:12 PM

Just this past weekend I installed the skybolt system for my RV8 cowling (along the sides too). The one thing I thought just a little odd was that retainer rivets spacing is in fact 1" but also uses 1/8" rivets vice 3/32" we are all used to using for nutplates.

I wouldn't use screws and nut plates on anything I plan to "routinely" remove as the locking feature of the nut plate tends to wear out as a function the number of cylces.

bobby · #8 02-02-2010, 01:13 PM

I'm sure the camlocs make removing the cowl an easy and quick job. Just how difficult is removing the cowl if it is attached according to plans with the hinge?

sandifer · #9 02-02-2010, 02:19 PM

Quote:

Originally Posted by bobby

I'm sure the camlocs make removing the cowl an easy and quick job. Just how difficult is removing the cowl if it is attached according to plans with the hinge?

Pins, like camlocks, are pretty quick and easy to deal with. However, I don't think most install camlocks because they're quicker or easier, but because the eyelets on the piano hinges can fatigue and break off over time. As they break off, the stress just gets more concentrated on the remaining eyelets, causing the rest to break off at a faster rate. I had this problem with the piano hinges on my upper cowl of the RV-3. I modified it with Skybolt fasteners, which worked extemely well.

Scott Hersha · #10 02-02-2010, 04:48 PM

I've built two RV's. My first one (RV-6) I used pins all around, per plans. My second one (RV-8) I used pins on the side horizontal split line, and camlocks on the firewall all the way around. My next one will be pins on the horizontal split line, and vertical portion of the lower cowl, and camlocks on the upper firewall and bottom of the lower cowl (two on each side of the exhaust for RV-8, 3 on each side for the RV-7/9). Upper cowl pins are difficult to install - especially on the -8 - and require too much alteration to make them last a long time, and the lower cowl bottom hinge pins are stressed from vibration. They eventually break (usually). Pins are elegant and easy to install and remove. Camlocks are more difficult to install during the build, but in the case of the upper cowl, they are very easy to use in the field for cowl removal. Just my opinion, your mileage may vary.....

Scott