Pmerems

Pmerems

Well Known Member
Advertiser
Gents,

I need to make my final decision on whether to use 1/4 fasteners on the top cowl to firewall attach on my RV-7A or the hinge. I have read all the posts but I still have some unanswered questions on the real life experiences with the 1/4 fasteners in my application.

I actually have drilled the hinge and have some experience with installation and removal of the pins. The cowl fit is very nice but a little awkward getting to the pins.

I actually purchased a kit from Skybolt for the upper cowl to firewall installation but need to decide if I will use it. If not I will post it for sale (at a discount on the forum).

Some of my questions are best answered by those who have installed the Camlocs/MilSpec/Skybolt with floating receptacle for only the upper cowl to firewall attach.

1. With the 1/4 turn retainers installed, can you easily get the top cowl off and on. Keep in mind I have the standard hinges used on the rest of the cowling attach. Some 1/4 owners actually leave the retainers off and use them as no-captive fasteners and have to remove them individually to get the cowl off.

2. Over time (best answered by those with Skybolt 4000 series or equivalent hardware) does the grommet wear into the painted cowl?

3. With the Skybolt kit there are floating receptacle with about +/- 1/16" of float. Do this allow the cowl to move too much even when the 1/4 turn fastener is tightened down. Any sign of abration on the mounting strip or inner cowl surface?

I am looking of the most maintenance free installation over time. 1/4 turn or hinge?

Any information or advice would be appreciated.
 
I used the Skybolt floating receptacles instead of hinges on the full cowl on my last two RV's. I would never go back to the hinge method as they break over time, and replacing the hinges messes up the paint job.
Installed per the instructions, I've never seen the Skybolt fasteners wear in a manner that would cause paint issues. Putting the top cowl on/off with them is a snap compared to the hinge method.


Pmerems said:
Gents,

I need to make my final decision on whether to use 1/4 fasteners on the top cowl to firewall attach on my RV-7A or the hinge. I have read all the posts but I still have some unanswered questions on the real life experiences with the 1/4 fasteners in my application.

I actually have drilled the hinge and have some experience with installation and removal of the pins. The cowl fit is very nice but a little awkward getting to the pins.

I actually purchased a kit from Skybolt for the upper cowl to firewall installation but need to decide if I will use it. If not I will post it for sale (at a discount on the forum).

Some of my questions are best answered by those who have installed the Camlocs/MilSpec/Skybolt with floating receptacle for only the upper cowl to firewall attach.

1. With the 1/4 turn retainers installed, can you easily get the top cowl off and on. Keep in mind I have the standard hinges used on the rest of the cowling attach. Some 1/4 owners actually leave the retainers off and use them as no-captive fasteners and have to remove them individually to get the cowl off.

2. Over time (best answered by those with Skybolt 4000 series or equivalent hardware) does the grommet wear into the painted cowl?

3. With the Skybolt kit there are floating receptacle with about +/- 1/16" of float. Do this allow the cowl to move too much even when the 1/4 turn fastener is tightened down. Any sign of abration on the mounting strip or inner cowl surface?

I am looking of the most maintenance free installation over time. 1/4 turn or hinge?

Any information or advice would be appreciated.
Click to expand...
 
Well since this is my first airplane I really have no experience, however...

I decided on milspec 1/4 turns just on the firewall portion of the top cowl. This should make it a lot easier to get the cowl on and off the first 25 or so times. Since I'm painting before I fly, easier is better as I plan to remove the cowl many times during my 40 hours and beyond.
 
I used Skybolt - no issues or regrets. The instructions they had at the time were kinda lame, but easily straightened out with a phone call.

erich
 
Skybolt

I wanted a mix of fixed and floating style receptacles on the firewall as recommended by Richard White (Bronze Lindy RV8) and Skybolt customized my order-so if you're concerned about movement just pick the style you want.

Mike
 
Useful thread...

I built my -4 with hinges per the plans and flew it that way for the first 400 hrs. By that time I had broken a number of hinge eyelets along the joints between the upper cowl and fire wall as well as between the upper and lower cowl halves.

I had planned to replace all the hinges with CamLocs, but in the end, used CamLocs for the upper firewall connection and switched to extruded hinge stock (rather than rolled) for the upper-to-lower cowl connection.

I did this because I was concerned about the cosmetics, stremgtj. duralbilty, and clearance to the valve covers for these sections. However, I did not want to use hinges for the sharply curved section of the upper firewall.

After 100 hours, things look pretty good. I am happy with both the extruded hinges and the CamLocs. In flight, I see slight bulging between CamLocs, but that is likely because I did not add the recommended stiffener to the cowl.

To answer your specific questions, I have not (yet?) seen signs of wear or vibration around the grommets. I use the retaining rings and have found it easy to install and remove the cowl.

Good luck,

Dean Pichon
 
Milspecs all the way

Paul,
I've built and flown 2 RV's now. The first was with standard hinges all the way around. On my '8 I didn't hesitate to use the Milspecs (all the way around and down the sides). I absolutely prefer it. Its not that the hinges are so bad, they're just not that great.

I find the adjustable receptacles work fine. The cowlings have a little give too them so its not a problem to put the top on or remove it.

I haven't noticed any paint issues around the grommets (yet).

One of the things I really like is the ease with removing and installing the bottom cowl now. Much better than with the hinges.

I can't imagine the fastener heads wearing out. You don't put loads of torque on them the way you do on a screw head. Just a gentle twist.

I'm sure you'll get plenty of "hinges are all you need" comments. Build what you think you want. You can fix it on the NEXT airplane.:D
 
milspecs here

I went with milspec 1/4 turn all the way around on my RV7a because I did not want to deal with the hinges. After 3 years, I now have 685 hours on the RV with no signs of paint cracking or wear around the camlocs. Looks as good as it did when it came out of the paint shop.

Good luck with what ever you decide.
 
I put Skybolts on the top FW portion of the cowl only, everything else is hinges. No real issues, but I might consider closing up the spacing by a half inch if I were to do it again (I get slight bulging of the cowl, but not really noticeable). No wear issues in 200+ hours.

FWIW, for my bottom hinge, I actually drilled a hole in the side of the cowl and insert the (bottom, horizontal) pins from the outside, with a retainer tab similar to that recommended for the upper-lower cowl hinges. I always thought that the van's method was kind of slapdash for those lower hinge attachments.

greg
 
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