[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]

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]

.....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]

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]

Camlocks or Milspec

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]

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!

 

[8CW]

...Because of the curvature of the cowling (among other reasons), I recommend using FLOATING nutplates in this application....

Rick, This is what I was planning to do as well, but could you please clarify for me what you said here. Did you use floating nutplates for EVERY hole on the cowling including the flat surfaces of the firewall and the horizontal sides, or just where the cowl has a curved surface such as around the front, and along the top of the firewall? Thanks.

 

[apkp777]

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

Can you explain what you mean by "shim and flange"? We're talking just a strap with nutplates right?

 

[sprucemoose]

Jeff Point convinced me and he was right for a change! (in case he's listening).

Even a broken clock is right twice a day...

And Roger, will I ever get my Skybolt install tools back? Or did you loan them to Darwin?

@Tony- Skybolt often has some pretty good airshow specials (I think I got them at 30% off back in around 2001) so waiting a couple weeks might pay off.

 

[LifeofReiley]

Can you explain what you mean by "shim and flange"? We're talking just a strap with nutplates right?

With the Vans cowl thickness you will need to have an 1/2" wide shim before the flange for the nutplate if you want a flush fit. I believe we used .040 as the shim. (shim then flange with nutplates). Works GREAT!!! a NICE FLUSH FIT.

 

[Mel]

I have the hinges on the sides, horizontal and vertical. Stainless Torx screws across the top, bottom and behind spinner. If I had it to do over again, I would do the same.

I have had occasion to "fix" several hinge attachments. If everything is aligned, they work great. If you're having problems with them check the hinge "eye" alignment. If one eye is out of alignment they become a pain.
I've had several customers say, "Change them to something else." After I rework their hinges, they love them.

 

[[email protected]]

so far i love my hinges...

with all of the fuss about hinges i approached attachment options with some hesitation. i ended up using hinges for all but the very bottom where several nutplates worked out better.

the side hinges are very slick and leave a nice clean line. hard to imagine a better solution on the sides...

the side bottom hinges easily fit full sized pins and are quick to deal with... same thing here what could be better than a solid easy attachment?

the top hinge frustrates many since access is somewhat restricted through the oil door and the need to fit the hinges with the outboard fuselage curves.

i think that van's compounds this frustration by suggesting that 1/8 pins must be replaced with .090 pins to make the arc... i fitted mine during the install with the 1/8 aluminum pins and found that the suggested .090 pins would hang up but when i used 1/8 stainless pins instead they slide in like butter!

removal of the top half takes less than a minute... most of the time is in removing the 4 screws at the bowl and the two holding the side pins.

try fitting 1/8 stainless pins on the top hinges. precurve the end and grind the tip, the precurved end makes starting the long pin especially easy as you guide it through the oil door.

 

[apkp777]

with all of the fuss about hinges i approached attachment options with some hesitation. i ended up using hinges for all but the very bottom where several nutplates worked out better.

the side hinges are very slick and leave a nice clean line. hard to imagine a better solution on the sides...

the side bottom hinges easily fit full sized pins and are quick to deal with... same thing here what could be better than a solid easy attachment?

the top hinge frustrates many since access is somewhat restricted through the oil door and the need to fit the hinges with the outboard fuselage curves.

i think that van's compounds this frustration by suggesting that 1/8 pins must be replaced with .090 pins to make the arc... i fitted mine during the install with the 1/8 aluminum pins and found that the suggested .090 pins would hang up but when i used 1/8 stainless pins instead they slide in like butter!

removal of the top half takes less than a minute... most of the time is in removing the 4 screws at the bowl and the two holding the side pins.

try fitting 1/8 stainless pins on the top hinges. precurve the end and grind the tip, the precurved end makes starting the long pin especially easy as you guide it through the oil door.

The tops LH is the one I am having trouble withi will give the 1/8 hinge a try.

 

[Rick6a]

Rick, This is what I was planning to do as well, but could you please clarify for me what you said here. Did you use floating nutplates for EVERY hole on the cowling including the flat surfaces of the firewall and the horizontal sides, or just where the cowl has a curved surface such as around the front, and along the top of the firewall? Thanks.

Bill,

I should have been more clear. I was referring to the upper cowl only. I use the hinges everywhere else per plans. As for nutplates, I'll offer your my observation on the subject. Fixed element nutplates such as included in the kits are fine for what they do, and in some cases even indispensible like when the nutplate has to have a dimple to accept a flush screw. Floating nutplates really come into their own when a large number of screws are required to fasten down a given assembly such as removeable floors or the upper cowl. Because the upper cowl is curved, a floating nutplate is especially desired because a floater is more likely to find the center of the screw threads without the chance of cross-threading that may well occur if you used fixed element nutplates instead.

 

[David Paule]

My 55 year old Cessna 180's cowling has sheet metal screws, with Tinnerman nuts holding them on. They go on and off quickly enough, certainly easier than the piano wire hinge cowling on the RV-8 next door.

The only downside is that after a while, 40 to 50 years, some of the holes might widen out a bit. And occasionally the cowl will toss a screw.

Of course anyone can see the screws. They aren't hidden from sight, if that matters to you.

The reason I mentioned the Tinnerman nuts and the sheet metal screws is that you certainly don't want or need machine screws and real nutplates riveted on. That's not only overkill, it would be considerably more difficult to remove and replace every time. The Tinnerman nuts slip over a little hat-shaped piece of aluminum that is riveted to the cowling, so there's still a bit of work to build it, but it's not much.

Look for an early Cessna 180, if you want to see how they do it. Mine is a '55.