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Which ¼ turn fasteners to use on the cowl?

airmel

Well Known Member
I've read a lot of the threads about the Skybolt and the Milspec quarter turn fasteners for the cowling, but I'm still not sure which to use. It seems that Skybolt has prefabricated tabs now which would cut down on the amount of work :), but I want the best looking (flush mount, no corrosion down the road, last forever, etc.). I am planning on using these just along the top cowl at the firewall with hinges everywhere else (except the very bottom!). I'd like to hear from those who have used these (Skybolt and/or Milspec) and some honest opinions! Which are the flushest? Which look the best? Which are the easiest to install/adjust? Thanks!
 
Skybolts

Skybolts work great. Easy to install and adjust. Drill the
15/32" hole not 1/2". Use a unibit to drill most of the hole
and finish off with a 15/32" bit. Unless you can find a 15/32" unibit.
Supplied mounting brackets work well. You may not
Need a shim between the braket and fire wall flange depending on the
thickness of the fiberglass cowling.
 
I feel the same way about the Milspec fasteners and their kits, which come with all the fasteners you need and the tools to install/adjust them. Great product, great service. I go with them again in a heartbeat.
 
I am a very happy Milspec customer. Easy to install and adjust for a nice flush fit. But, I have no experience with Skybolt, so cannot give a meaningful comparison. I imagine most of the responses will be similar. Hopefully someone with experience with both products will speak up.
 
I have the skybolts but have not installed them yet and I'm with Jay I think the hinge method looks better so I am thinking about not even using them.
 
Skybolts worked well for me

Can't comment on Mil Spec other than I think the fasteners themselves are equal. Check what other parts of the system are available though. With SB's they have the interlocking tabs and an alignment jig (guide) to drill the holes that are extremely useful (even very small hole errors can cause the heads to do weird things). Both add up to make the job much easier. I don't know if MS has those. If they do I guess you can use price to guide you. Good luck.

Skybolts work great. Easy to install and adjust. Drill the
15/32" hole not 1/2". Use a unibit to drill most of the hole
and finish off with a 15/32" bit. Unless you can find a 15/32" unibit.
Supplied mounting brackets work well. You may not
Need a shim between the braket and fire wall flange depending on the
thickness of the fiberglass cowling.
 
I have milspec but never installed them. Kind of wishing I had now. The horizontal long hinge pins are still a royal pain to install even after a year of flying. They are so tight I have to use vice grips clamped every two inches at a time to push them in.
 
Now that Paul Dye has found a source for undersized hings wires, I'd probably go with the original hinge design and use one of the undersized wires. As Paul suggested, get the range so you start with one of the smaller sizes, adn once it get too easy, move up a size. etc.

As for my airplane, I have fasteners (across the back of the top cowl) ... which look surprisingly like the ones on a Corsair II :cool:
 
Hi all

I am at the same point i.e. skybolts or the horizontal long hinge pins thingys. Does anyone have a picture of any of the examples - Looks like I may settle on skybolts but not 100% sure. Lot of the local guys moaning about the long hing pins thouogh. Any help on this would be greatly appreciated
 
Can't comment on Mil Spec other than I think the fasteners themselves are equal. Check what other parts of the system are available though. With SB's they have the interlocking tabs and an alignment jig (guide) to drill the holes that are extremely useful (even very small hole errors can cause the heads to do weird things). Both add up to make the job much easier. I don't know if MS has those. If they do I guess you can use price to guide you. Good luck.

Milspec also have the alignment jig. I don't know what the interlocking tabs are, so can't say if Milspec has them or not.
 
Hate the Hinge

I currently have a RV-9A with only 1/4 turn fasteners for both the top and bottom cowl. Love it and to me it looks good. both cowls on or off in less than three minutes.

My previous plane was a GlaStar and it had 1/4 turns across the back of the top cowl but also had two hinges on the side of the cowl. I absolutely hated trying to get the hinge pins in. It was tough no matter how you did it. Yep, tried graphite, tried tapering the pins and nothing I did worked. It sucked. In fact it was a significant reason not to pull the top or bottom cowl.

It is obvious some people have no problems with hinges and some are more caring about the visual impact of the 1/4 turns but give me 1/4 turns any day.
 
I currently have a RV-9A with only 1/4 turn fasteners for both the top and bottom cowl. Love it and to me it looks good. both cowls on or off in less than three minutes.

My previous plane was a GlaStar and it had 1/4 turns across the back of the top cowl but also had two hinges on the side of the cowl. I absolutely hated trying to get the hinge pins in. It was tough no matter how you did it. Yep, tried graphite, tried tapering the pins and nothing I did worked. It sucked. In fact it was a significant reason not to pull the top or bottom cowl.

It is obvious some people have no problems with hinges and some are more caring about the visual impact of the 1/4 turns but give me 1/4 turns any day.

Agreed. I've got Milspec 1/4-turn fasteners on my 172 cowl and love it, they will be on my 9A.
 
skybolts

I only have 5 hrs. of flying but have removed cowl for inspection several times and several times before flight. I really like my skybolts. We built a 3 piece cowl so cooling and intake boots, and close fit behind spinner do not need to be messed with when removing top half. Spacing was kept at about 3 inches for good fit. It is a very task removing cowl. Ron
 
Thanks for the replies. I guess the two fasteners look very similar on the airplane, both are adjustable, etc. So with the Skybolts including the tabs premade, it looks like they have the advantage right now...

Any more thoughts and/or comments?
 
Milspec for sale?

Don't mean to hijack the thread, but Jim Wright, if you're not using the ones you have, I'd be interested in 17 of them.:D
 
Bumping the thread

My James Cowl is on the Roadrunner truck in transit to me so I'm at this stage - deciding on 1/4 turn fasteners, SB vs Milspec.

Can anyone give some updated comments to those 5 yrs ago, like lessons learned etc?

Thanks
 
I installed the Milspecs on my RV-9 three years ago and installed the Skybolts on my RV-10 few weeks ago. From an installation perspective, I prefer Milspecs. For cowls operation, I thing both will give good results over the long run.

Michel
 
I had 2 different RVs guys rent hangar space from me both with hinged cowls. I would help them remove and install their cowls. It was always a 2 man job and a PITA.

I went to visit a friend who did his 6 with Skybolts and I watched him take the top off himself in about 30 sec. He reinstalled it solo in under a minute. He said they made it practical to remove the top for preflight inspection, rather than hopefully peering through the tiny oil door. He found it to be a safety enhancement. I was sold. But to each their own.

Even though it is not as clean as the hinge method, they still look very nice.
 
I used the SkyBolts and like them, but a few tips may be in order...

I used floating receptacles *except* for a few locations, like the upper and lower aft corners, to "lock in" the position of the cowling. In addition, I added a small bracket inside the lower cowling that mates to an angle with a nutplate attached to the flange/firewall to make it even more secure. If you don't, the whole cowling can shift (even with non-floating receptacles) some fraction of an inch. I added one screw on each side of the bottom of the bottom cowling, as well, for the same reason.

It was a bit more work, not much, and it's pretty quick to remove the screws when taking off the lower cowling, but it does tighten everything up.

The SBs make removal and reinstallation really quite straightforward and easy, and I think they look good (YMMV). Biggest pain is dealing with the nosegear leg while sliding the lower section down (or up) and getting things lined up to flip the baffling material over the ramps, but that'd be the same regardless of attach method with an A model.
 
SkyBolts

I just replaced all but the side vertical hinges on my 6A. This is the biggest build project (except for a new GRT panel) I have ever done. Can't believe I didn't do this when I bought the plane 2 years ago when I first bought it.

Love em.
 
I have hinges on my cowls, they are quick and easy to remove and install. I've taken off plenty of cowls with MS and SB fasteners and honestly I find my hinges are as quick or quicker than the MS/SB units, I also think they look better.

Trouble is most folks just don't take time and attention to install the hinges with the care required which will result in pins that are difficult to install.
 
I agree with Walt on installing the hinges. They are a much cleaner installation. I have them on my RV9. The key with the hinges, I have found, is to wipe the pins clean and spray them with silicone EVERY time I remove them. It makes all the difference in the ease of installing and removing the pins.

The hinges on the bottom of the cowl started breaking the eyelets closest to the exhaust pipes at about 80 hours. I removed the hinges and installed the milspec 1/4 turns across the bottom of the cowl and have had no issues with about 500 hours now. I suspect this area of the bottom cowl is a high vibration area.
 
I have hinges on my cowls, they are quick and easy to remove and install. I've taken off plenty of cowls with MS and SB fasteners and honestly I find my hinges are as quick or quicker than the MS/SB units, I also think they look better.

Trouble is most folks just don't take time and attention to install the hinges with the care required which will result in pins that are difficult to install.

I installed sky bolts (7) and my 10 friend did a by-the-book hinges. He can either remove or install his cowl just as about as fast as I can with SB's. And they won't pucker. :D

So, apparently, there is no "wrong" choice - it's personal.
 
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