Screws and nutplates to attach cowling?

[apkp777]

Hey all,

I currently have the stock Van's hinges. I am loving them less and less every time I de-cowl.

Skybolts are $650, Camlocs not great.

How about screws and nutplates. I know some have done this. Anyone willing to give me some pros and cons?

I know it might take a bit longer to get the cowl on and off, but not significantly I don't think. What's the downside?

[Ironflight]

Louise's RV-6 has screws and nutplates along the sides, and on the belly (for the aft end of the cowl). It reminds me a lot of the old Grumman cowl (since you're an A&P, you might have worked on those).

It works, and while it takes a little longer to cowl and uncowl than it does my -8 (all hinges), the biggest issue is probably just seeing all those screws. And, of course, the inevitable stripping of screw heads, having to go find a new screw, etc. More chances to ding the paint with a screwdriver, and the tinnerman washers never match the paint....so basically, in my book, it is appearance.

(One data point - Yesterday I needed to take some alternator pictures - didn't matter which airplane. I elected to take the cowling off the -8 instead of the -6 because it is faster and easier.)

[revenson]

If you want an alternative to Van's method, just bite the bullet and get the skybolts. Spendy, but you can be confident of this solution and you won't regret it. Jeff Point convinced me and he was right for a change! (in case he's listening).

[apkp777]

Originally Posted by Ironflight

Louise's RV-6 has screws and nutplates along the sides, and on the belly (for the aft end of the cowl). It reminds me a lot of the old Grumman cowl (since you're an A&P, you might have worked on those).

It works, and while it takes a little longer to cowl and uncowl than it does my -8 (all hinges), the biggest issue is probably just seeing all those screws. And, of course, the inevitable stripping of screw heads, having to go find a new screw, etc. More chances to ding the paint with a screwdriver, and the tinnerman washers never match the paint....so basically, in my book, it is appearance.

(One data point - Yesterday I needed to take some alternator pictures - didn't matter which airplane. I elected to take the cowling off the -8 instead of the -6 because it is faster and easier.)

The main concern I have with the screws is that after a while the holes get wallered out and start to get sloppy. And yes lot's of planes used screws. I am not a huge fan of the idea. At this point I suppose Skybolts are probably the way to go. Just tired of spending $$ on the plane. Especially $650 on something that doesn't have blinking lights, say "terrain terrain" or make me go faster.

[Rick6a]

Originally Posted by apkp777

.....How about screws and nutplates......Anyone willing to give me some pros and cons?.....

I've done it both ways....hinges and nutplates/screws and in the end I grudgingly prefer the latter. Sure, hinges do impart a cleaner exterior look but they can be a PITA. My main gripe: Ever try to reach deep inside the oil door access while the engine compartment is still hot and then pull out a hinge pin, especially the hinge pin located on the starboard side? To remove it, you have to push the pin towards the port side of the firewall until the pin finally clears the last hinge eye, all the while your arm is reaching deeper and deeper into that hot engine compartment through the opened oil door. Not fun:

Compared to fancier alternatives, screws are far more economical. Because of the curvature of the cowling (among other reasons), I recommend using FLOATING nutplates in this application. A power screwdriver makes short work of removing or reinstalling 24 or so screws and I just don't fret about worn screws. If a screw even hints at becoming worn I just toss it out and replace it with new and I'm always looking for a reason to replace screws. Screws are cheap. A hundred or so spare #8 screws will last years. I stopped installing tinnerman washers under the screw heads awhile back when I finally decided they weren't really needed....anywhere.

Personally, I have never experienced screw holes wallowing out. I retrofitted nutplates on my old C-150 cowl to replace the badly rusted and sometimes broken spring steel Tinnerman nuts that use sheet metal screws for attachment. In 18? years and uncounted cowl removals later, I never experienced a single wallowed out screw hole. My -6A has been flying since 2005 and wallowed out screw holes are non-existent.

No doubt, under most circumstances a well-built hinge pin system will make shorter work of cowl removal and I do favor the look of hinges but this is one situation where I percieve a bit easier UPPER cowl removal by deferring to screws. After all, easier cowl removal is the main reason so many builders willingly pony up an additional $500 or more for Skybolt etc. For sure, that is a lot of money compared to installing nutplates that by my guesstimate should cost something well less than $100 in direct comparison.

Its your airplane and ANY cowl fastening system will have its advantages and disadvantages. This is just one in a long line of choices the RV builder faces so the bottom line is do what feels right for you.

[apkp777]

[quote=Rick6a;446734]I've done it both ways....hinges and screws and I like screws and nutplates. QUOTE]


Thanks Rick. That's great info. I was leaning toward screws and nutplates mostly because of cost. It appears that they also function well too. Yeah, I can see that a floating nutplate would be better in this installation. Stainless screws look good to me. I too am not a fan of tinnermans unless I have to use them I won't. I know your an old time Douglas guy. I am surprised you didn't use Tri-Wings?

I suppose I have probably take out and installed several hundred thousand screws on aircraft in my life. 20-30 each time I pull a cowling isn't a big deal.

Did you use .050 or .063 for the strips? Looks like .050 from the photo?

[Rick6a]

....050 or .063 for the strips? Looks like .050 from the photo?

Good eye. The strap and 2 more just like it (for other local builders) was sheared from a 4' X 4' piece of .050. At 48" long, it's length was perfect.

[PaulR]

Great timing on this question. I bought the Milspec fasteners a year or so ago after reading some comments on this list. Now I'm assuming, Tony has heard something bad about them?? I know they are significantly cheaper than Skybolts but is there an inherent problem with them? I'm just getting ready to start fitting the cowl and don't want to put something in there that I'll regret.

[apkp777]

Originally Posted by PaulR

Great timing on this question. I bought the Milspec fasteners a year or so ago after reading some comments on this list. Now I'm assuming, Tony has heard something bad about them?? I know they are significantly cheaper than Skybolts but is there an inherent problem with them? I'm just getting ready to start fitting the cowl and don't want to put something in there that I'll regret.

Paul, Milspec kits are about the same $$ as Skybolts. $500 for the fasteners, another $75 for tools and $75 for aluminum straps.

[LifeofReiley]

Torx screws and nutplates... the perfect solution. I used a shim and flange setup, no pins anywhere and love it!