pmccoy

pmccoy

Well Known Member
Hi All-

I bought a complete set of Mil Spec Quarter Turn Fasteners in a VAF group buy awhile back. Since then I have moved my project to the airport, so I get lots of guys coming over to talk planes. Lately I have been finishing up some work on the panel brackets and I tell them my next step in the build is to start working on the cowl with the Quarter Turn Fasteners. At this point, the eyes start rolling. The old guys keep asking why I would not just go with the standard VANS piano hinges?

So here I am, wanting to start the installation and I find myself questioning the decision to use Quarter Turn Fasteners.

I am looking for Pros & Cons of each. For those of you who have installed the Quarter Turn Fasteners, are you happy? Have there been any problems? Would you install them again on your next project? Did you go firewall only, or the complete cowl?

Anyway, I am still leaning towards using the Mil Spec fasteners, just wondering if others agree with this decision. Thanks.
 
I'm using them and find they are easier to to work with than the piano hinges.

In addition, the piano hinges are not to break on the bottom and these don't have that problem.

About the only cons I can think of are the fasteners takes slightly longer to get the cowl off. Putting it on I would think the hinges take longer because you have to line everything up. The other big con for some people is strictly esthetics, you see the fasteners where you don?t see the hinges. For me, it is a machine, so I would like to look like a machine.
 
I used the piano hinge solution on my -6A...

...just the way Van called out. I am in my Phase I testing, so I have no long term opinions as yet. My only "gripe" with them is that I have to let the engine cool down before I stick my hand into the oil filler door opening to remove the hinge pins.

It's HOT in there after a flight. I have been doing my due diligence after each flight, taking the cowling off and looking for anything out of the ordinary. I would like to at least get the top cowling off to let things cool down quicker, but I just can not do that with the hinge solution. Once cool, I believe I can remove the top cowling quicker than a RV-7 friend who has the 1/4 turn fastener solution.

Otherwise, the hinge pin solution works well for me. One of the nice things about the hinge solution is that I do get a lot of comments on how smooth / streamlined / sleek the aircraft looks.
 
Peter

The "old guys" will drive you crazy. Build it the way you think you want it.

As far as objective results? My RV-9A had classic Vans piano hinges, and yes, they've "worked" for the last 5 years.

I'm just now finishing my RV8 and it has a complete set of Mil-Specs. No hinges anywhere. An excellent use of $500 I think. They look good, they work well. I'm sold.
 
The "old guys" will drive you crazy. Build it the way you think you want it.
Click to expand...

You are so right! I get all sorts of advice now that my plane is sitting in an EAA chapter hangar. Everyone stops by and gives me there .02?

Mostly I like all the suggestions, but when I have a differing opinion I start doubting my reasons... must say something about me :)
 
A good way to go, Peter...

.....is to use the fasteners around the top rear cowl, spaced at 4" intervals and three per side under the bottom cowl, with piano hinges on the sides and vertical ones for the bottom cowl. The piano hinge pin is .090" and the eyes are .125", a .035" gap and allows the cowl to move/vibrate slightly and eventually you'll see 'smoke' behind the top cowl with the hinge setup.

Best,
 
I used them on the top half of the cowl. I really like them, the Milspec ones I used are top quality. The cons? Well making the scalloped parts for holding the recpticles was a bit more work than the hinges but I would use them again for sure. The best defense against the EAARP;) crowd is to ask to look at their plane so you can see what they are talking about:D Seems every comment starts out "Well on my RV-6A":p
 
Tools

I think it's appropriate place to ask if somebody wants to sell/rent installation tools. Particularly I am interested in Camlock pliers and tapered shank tool for retainers. Just asking before ordering from the manufacturer. Thanks for looking,
 
Its up to you...

You probably wont find anyone who does not like the fasteners that they chose to put on, but walk the line at any air show and you will find 10 to 1 hinges over fasteners. They have been the standard for Van's on all models I am sure for good reasons, not just cost.
I have 1/4 turns on my Bucker and hate them, but that is not a fair comparison to an RV. I dont think they where done correctly.
As others have said, build what you want and I dont think you can go wrong either way, but much like tip ups vs sliders, you wont find someone who built one or the other tell you they hate it.

I love the comment about the "old guys", just ask them to show you their RV and they shut up quickly. Anybody that builds one and owns one will support you all the way with whatever your decision because they know what it takes to get the job done, anyway you choose to do it.
Have fun!
 
2nd Pierre's suggestion

I did 1/4 turns along the firewall on the upper & lower cowls. If I were to do it again, I would just do the upper.

I think the hinges provide a more consistent fit during the cowl fitting process. It spent lots of time tweaking the cowl to firewall seam with the 1/4 turns. One day it would fit perfectly and the next day there would be a gap or an overlap. I think the hinges "lock things in place" more and the hinges look good.
 
How about screws?

My understanding is that the quarter turns are hard to keep in adjustment due to the variable thickness of fiberglass and ultimate wear of the pieces. The hinges don't seem to care about that, but are more of a challenge to make work smoothly. I used countersunk screws with nutplates and it seems to work well and was quite easy.
 
Grandy said:
My understanding is that the quarter turns are hard to keep in adjustment due to the variable thickness of fiberglass and ultimate wear of the pieces. The hinges don't seem to care about that, but are more of a challenge to make work smoothly. I used countersunk screws with nut plates and it seems to work well and was quite easy.
Click to expand...

Randy,
Details please! What size screws did you use? Did you use trim washers around the screw heads? What spacing on the screws? Can you post a photo or two of your installation?
Charlie Kuss
 
Cowl Milspecs

I am presently installing my cowl on the 6, and have some hesitation about running the Milspec fittings, on the horizontal sides, too far forward. Here's why:

My friend, an old A&P, took a look at my milspec cowl attach planning and told me a story about how he did the same thing on a non-Vans experimental but found that he could not easily or conveniently lift the upper cowl off with the quarter-turns run all the way forward. He thought he had outsmarted himself. I am considering following his advice, but I have not read of this issue in searching the forums.

Perhaps I will use screws and washers on the forward end, and begin my row of Milspecs behind that. Should take a pretty close look to see the transition.

Well, that is all. Any thoughts appreciated.


Montanamike
RV6 N918MB FK
Working Like A Dog
 
That's what happened on my Bucker.

Grandy said:
My understanding is that the quarter turns are hard to keep in adjustment due to the variable thickness of fiberglass and ultimate wear of the pieces. The hinges don't seem to care about that, but are more of a challenge to make work smoothly. I used countersunk screws with nutplates and it seems to work well and was quite easy.
Click to expand...

And once they wear, they are a mess to deal with. Once again, perhaps not a fair comparison. There are several different sizes that where used to make up for the different thickness and there are a lot more parts than just a top and bottom cowl, so I think the RV's would have much less of an issue with this.
 
We have two and a half RV's in our hangar now, and none of them are (or will be) the same. The Valkyrie has hinges everywhere, just like Van intended! I like the very clean look, and it takes me very little time to remove the entire cowl - quicker than the RV-6, which has screws on the sides (between top and bottom) and under the belly with hinges and wires on the top and sides. On the -3 project, I am leaning towards camlocks on the firewall to cowling line, and hinges/pins along the sides - I just think that with the geometry of the cheek cowls, camlocks will be easier there.

All of the systems work, and all have downsides. Hinge pins on at th firewall can be a little tough to install sometimes, but once you learn to hold your mouth just right (and they wear in), they'll be as fast as Camlocks to replace and remove. And they do give a nice tight fit. The screws on the RV-6 cowl mean that you have a handful of greasy #8 countersunk screws to put somewhere, and you better have a few new spares, because heads get stripped regularly. Camlocks are (like screws) visible - if very clean lines are your thing, then they'll disturb you.

But they all work!

Paul
 
I've got the Mil-Specs on my cowl and I love them. I like the look of the fasteners; somehow it seems very business-like to me. Anyway, regarding a couple of comments, here is my experience at 100 hours. I ran the fasteners all around the perimeter and to the front of the horizontal parting lines (but not next to the spinner; there is no room between the cowl and prop-shaft for the fastener body, so you use nutplates and screws there which are supplied in the Mil-Spec kit). The firewall fit seems a little sloppy until you get both cowls fitted together, at which point everything locks into place. Looking at a friend's RV with hinges, I don't see any difference in fit. The comment about having the fasteners all the way on the horizontal might be a concern on some cowls but the RV cowl is flexible enough that the fasteners easily clear the edges of the lower cowl to fit home in their sockets. Regarding wear, the fasteners consist of a metal grommet in the outer surface, a receptacle (or metal body) on the inner surface, and the fastener itself. I am seeing no wear on the cowl and the parts can be replaced if necessary. The receptacle adjusts for depth and can be re-adjusted if needed; I broke a couple of fasteners because I had adjusted the receptacles too tight, so I re-adjusted and replaced the fasteners and no more problem.

I see a couple of drawbacks. I can get my upper cowl off pretty quickly but the lower cowl requires a creeper or crawling around under the aircraft. Also, I know that if something happens and a fastener pulls through the cowl (grommet and all) then it will be a nasty fiberglass repair. And I do worry a little bit about fretting around those grommets but so far haven't seen any. However, I think the system is great and am planning to use it on the -10 when I get that far.
 
got them also

I have Mil Spec camlocs on an RV7a with 655 hours on and no wear on cowling. I used them everywhere, all around the cowling. They are adjustable, so it makes no difference if cowling thickness varies as each is adjusted for that location. I am very pleased with them and would do the same thing again.
 
FWIW, I made a point of thickening the cowl edges where I expected to use 1/4 turns. A few plies of glass tape does the trick. The result is more bearing area for the grommet and should result in less wear.
 
Milspecs

I used Milspecs along the top cowl at the firewall, and am really glad I did. Hinges everywhere else. No wear to be seen, but I also thickened the cowl lip like Dan did. This eliminates the pucker that you usually see in this area if the FG is too thin. Pitch is 3.75 inches along the top, but you will have to space them a little differently on the sides to clear all of the curves and angles. I am considering using them on the lower hinge line at the firewall on my current project. ( at the belly) I see some minor wear on the hinges at this point on my 9A.

No regrets,
Chris
 
Thanks for the advice...

... on the fasteners. I have gone back and forth on this decision and hearing from others is really helping.

I am not building a speed machine, so having the ultra clean lines of the hinges is not a priority. In my opinion, both solution look like an airplane, so to me the visual isn't a factor.

My original goal was for ease of use down the road. I had heard stories of the hinges either cracking or being difficult to install on the firewall. So I think my choice will be to use the Mil Spec fasteners on the firewall, and go with the hinges on the horizontal lines. Again, thanks to all for the comments.
 
pmccoy said:
... on the fasteners. I have gone back and forth on this decision and hearing from others is really helping.

I am not building a speed machine, so having the ultra clean lines of the hinges is not a priority. In my opinion, both solution look like an airplane, so to me the visual isn't a factor.

My original goal was for ease of use down the road. I had heard stories of the hinges either cracking or being difficult to install on the firewall. So I think my choice will be to use the Mil Spec fasteners on the firewall, and go with the hinges on the horizontal lines. Again, thanks to all for the comments.
Click to expand...

If you do not mind getting one more piece of advice ...

While I am still a good way from the point you are at, I have already decided to use the Quarter Turn Fasteners because I plan to use a three-bladed prop on my RV. Therefore, I expect that these fasteners will make it a bit easier to get the cowling off and on a plane with a three-blade prop.

Thanks much!
 
You sure?

Crossbow said:
If you do not mind getting one more piece of advice ...

While I am still a good way from the point you are at, I have already decided to use the Quarter Turn Fasteners because I plan to use a three-bladed prop on my RV. Therefore, I expect that these fasteners will make it a bit easier to get the cowling off and on a plane with a three-blade prop.

Thanks much!
Click to expand...

I would think it would make it more difficult? Once the hinge pin is pulled, the mating surfaces slide away or pull apart. With 1/4 turns the "screw" has to clear the socket. Others have commented that this makes it tough to disconnect the sides? It may not matter either way.
There are some very good ideas in other threads about dealing with 3 blade props as far as cowling modifications. A lot also depends on whether you are horizontal or vertical induction.
 
Vladyspassky said:
I think it's appropriate place to ask if somebody wants to sell/rent installation tools. Particularly I am interested in Camlock pliers and tapered shank tool for retainers. Just asking before ordering from the manufacturer. Thanks for looking,
Click to expand...

I have both tools, the pliers are a must have from what I've seen. They work great. I initally used the retainers until I painted the cowl and removed the fasteners. I never used the retainers after paint. The cowl is VERY easy to R&R without the fasteners hanging up on the recepticles. Slip the cowl on, pop in the 1/4 turns and engage. If you want to borrow the tools no problem but postage in the long run may rival the purchase costs.
 
Makes sense...

Rick S. said:
I initally used the retainers until I painted the cowl and removed the fasteners. I never used the retainers after paint. The cowl is VERY easy to R&R without the fasteners hanging up on the recepticles. Slip the cowl on, pop in the 1/4 turns and engage.
Click to expand...

The keepers are what cause me the most grief. Unfortunatley, due to the inconsistency in my Bucker cowl, the fasteners are a bunch of different lengths. Getting them back in the right spot when they fall out is a real challenge. I see how this would not be an issue for the RV Cowl.
 
Catto 3-Blade Prop

While I am still a good way from the point you are at, I have already decided to use the Quarter Turn Fasteners because I plan to use a three-bladed prop on my RV. Therefore, I expect that these fasteners will make it a bit easier to get the cowling off and on a plane with a three-blade prop.
Click to expand...

Ok, this is a new one to me. I have a Catto 3-Blade prop and a Vertical induction system. Am I going to have issues pulling the cowl? Is this a combination that requires mods to the cowl? Is this effecting my decision on the Quarter Turn Fasteners...

I will start searching for old threads, as I have not noticed this issue before.

Thanks.
 
On the Rv-10 the cowl needs to have the nose gear opening extended forward to allow the cowl to be lowered enough to clear the two blades of the prop that are below the thrust line. That is the only thing I had to modify. IMHO the 1/4 turn fasteners WITHOUT the retainers make for easier cowl removal and installation. As far as a three blade requiring any additional mods I can't see where there would be any for that...now vertical induction has the FAB to snorkel clearance/seal to deal with but horizontal induction with the air duct to the front left intake should not be an issue regardless of hinges or 1/4 turn fasteners.
 
JonJay said:
the fasteners are a bunch of different lengths. Getting them back in the right spot when they fall out is a real challenge. I see how this would not be an issue for the RV Cowl.
Click to expand...

I'm not familiar with different length fasteners, the Milspecs recepticle is adjusted for depth and the 1/4 turn fastener is standard length, I don't worry about which one goes back where.
 
That is a bunch smarter than mine...

Rick S. said:
I'm not familiar with different length fasteners, the Milspecs recepticle is adjusted for depth and the 1/4 turn fastener is standard length, I don't worry about which one goes back where.
Click to expand...

Good information Rick.
The standard 1/4 turn hardware I am familiar with have the sockets fixed. Sounds like I have stupid hardware! This is good information if/when I ever restore the Bucker, I would change to the adjustable sockets, and loose the keepers. I think I would be much happier with the system.
I guess all 1/4 turn stuff is not created equal!
 
pmccoy said:
Ok, this is a new one to me. I have a Catto 3-Blade prop and a Vertical induction system. Am I going to have issues pulling the cowl? Is this a combination that requires mods to the cowl? Is this effecting my decision on the Quarter Turn Fasteners...

I will start searching for old threads, as I have not noticed this issue before.

Thanks.
Click to expand...

Pete:

I will see if I can dig up the exact statement that I am referring to later today.

But to paraphrase it in the meantime, he said that while one could use the hinge pin method with a three blade prop, however he found it easier to use the quarter-turn fasteners instead. And since I am working on first RV, I expect that I will be doing a bit more than the usual cowl and de-cowling work so I like the idea of the quarter-turn fasteners.
 
Peter-

"When I build my next plane...." :eek: I will use milspecs around the top firewall and bottom firewall, and use hinges for the bottom cowl firewall sides and the top-bottom cowl seam. The top curves make for tough pin insertion and at the bottom there seems to be a track record of eyelet failure.

I currently have all milspecs for everything on my top cowl (firewall and horizontal) and use hinges on the bottom cowl at the firewall. They all work great, but next time I'd save my money and not buy so many milspecs.:eek:
 
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pmccoy said:
Ok, this is a new one to me. I have a Catto 3-Blade prop and a Vertical induction system. Am I going to have issues pulling the cowl? Is this a combination that requires mods to the cowl? Is this effecting my decision on the Quarter Turn Fasteners...

I will start searching for old threads, as I have not noticed this issue before.

Thanks.
Click to expand...

Peter:

Just in case you are still asking for opinions, below is one of the bits of data that helped to sell me on the value of cowl fasteners versus hinge pins.

Although it is not quite the data I originally discussed, I do believe that it makes a good case for the use of fasteners all the same.

Thanks!

http://www.vansairforce.com/community/showpost.php?p=135907&postcount=2
 
They Rock

1/4 Turn Fasteners Rock! My cowl is nice and tight and fast to take on and off which saves a lot of time and aggravation, especially in Phase I.

Hans
 
Peter,
I work on several RV's through out the year in all different configurations. My RV4 is 14 years old with 1100 hrs on it. I have all hinge pins in it and the only problem I have had is the upper right hand corner (twards the top of the cheek) will loose an eyelet. This has happened twice. I simply replaced that section of hinge on the cowl side. Other than that the pins work well and in my mind are the best looking and are easy to get on and off. With that said the quarter turns work well and you will probably have no issues. The only draw back I have seen is when someone uses the quarter turns on the upper firewall and the hinges on the sides. It makes it difficult to get the top cowl to drop into place without alot of finageling sometimes causing chiping paint. Having said that my rocket will have quarter turns on the upper firewall and hinge pins everywhere else. (I am a glutton for punishment) This should eliminate any problems with upper hinge pin breakage. Any way you choose will work just fine.
Ryan
 
Ryan

How is the Rocket coming along? What engine are you installing? The IO-540?
Being an Aircraft Mechanic you probably can overhaul a run-out...(?)
 
They just look like airplane stuff

Milspec is great. Just ask for Jeremy.

Milspec%20001.jpg


Milspec%20002.jpg


Milspec%20003.jpg
 
Bob,
The rocket is coming along fine. I have been somewhat distracted the last couple of months but should be on track after the holidays. And I will be overhauling my 540 after the first of the year. Cant wait!!
Ryan
 
Thought I knew this crowd...

Bob Kuykendall said:
Remember, if you get the metric versions you have to call them (pi/2)radian turn fasteners.
Click to expand...

I'm disappointed that nobody commented on this one. I think it's hilarious.

I'm interested in the construction of the fastener mounting strip on the RV-4 firewall. The RV-3 and RV-4 have flat firewalls, and with the sloping profile of the fuselage all the way around the sides and top, I'm not sure a flat strip of material will fit around the entire profile and fit flush against the cowl at the same time. Has anyone worked through this issue with success? It seems a slightly curved strip is necessary.

Also, what size of material is used for the mounting strip?
 
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