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Inatalling Vans Crotch Strap Brackets for Crow Harnesses

longranger

Well Known Member
Installing Vans Crotch Strap Brackets for Crow Harnesses

I'm working on the center section of my RV-7 fuselage, and I want to install the Vans crotch strap brackets before riveting the ribs to the belly skin. Per the photo below that I got from Fred Crow, I know the strap fitting is longer between the bolt hole and the strap slot, so I'll have to lower the bolt hole accordingly to get the slot in the fitting centered in the relief holes in the brackets.

I've read everything I can find on the fore/aft spacing of the brackets for use with Crow 5-point harnesses. Some say 3/16-inch, one says 5mm, some say 5/16-inch. I've talked to Fred Crow, and he says that belt fitting is about 0.120 thick.

Does anyone know why the brackets shouldn't be spaced at 0.125, per the plans?

Crow%2520Crotch%2520Strap%2520Fitting.jpg
 
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I just installed the same brackets in an RV 6, I used .125 spacing for the Crows and it worked out fine.
 
Miles,
I used the Van's spacing for the croch strap and it worked out fine it is tight, my only problem was is when installing the floor panels I found it is easier when I lay the floor panels down to screw the flanges on the croch stap first the fasten down the rest of the floor panels. I have had to use a long wooden dowel to push on the flange under the floor panel to get the screws started on a couple of cases.

Once you get is roughly lined up the rest goes easy.

Jack
 
Miles,
I used the Van's spacing for the croch strap and it worked out fine it is tight, my only problem was is when installing the floor panels I found it is easier when I lay the floor panels down to screw the flanges on the croch stap first the fasten down the rest of the floor panels. I have had to use a long wooden dowel to push on the flange under the floor panel to get the screws started on a couple of cases.

Once you get is roughly lined up the rest goes easy.

Jack

Had the same issue as Jack, so if you were to space the brackets 3/16's you would probably be fine.
 
John and Jack, thanks for the replies. I think I'll space the brackets a bit over 0.125 to make dropping the belt fitting in place a bit easier.

Are the Hooker fittings really thick enough to require 5/16 spacing, or are the belts sewn at the fitting, keeping them from being unthreaded to install the fitting?
 
Why not just use the crow seat belt piece as a spacer while you drill the brackets in place? That's what I did. The seat belt brackets are pop riveted in place and a pieces of cake installing in a completed fuselage.
 
Be sure to enlarge the hole in the crotch bracket for an AN5 bolt before you rivet everything in place. I had to buy a stubby threaded shank 5/16" bit for my angle drill to get the hole sized right. On the crotch belt strap fitting, just position the belt in the right place for the slot, then drill a new 5/16" hole in the metal fitting to align with the stock hole in Van's bracket. This way you get the advantages of having the correct location of the crotch strap to the bracket, and don't need any spacers or washers to fill the extra large hole in the Crow fitting. Do the same for the AN4 hardware where the lap belts connect.

You can see the extra holes on the lap belts here.
IMG_0257-M.jpg


You can see how the lap belts are attached to the seat anchors here.
IMG_4592-M.jpg
 
To make things easier I just swapped the end fitting on the crow harness to a standard triangular fitting. I didn't have to change any bolts, locations, or spacing. I happen to have had two end fittings laying around leftover from a cessna harness so it was no big deal.
 
Does anyone know if Crow or Hooker will send you a "test" crotch strap and hardware to get things sized up? I've already installed my brackets per the plans and I now a bit nervous that I'm going to be having problems when the day comes to install it.
 
Why not just use the crow seat belt piece as a spacer while you drill the brackets in place? That's what I did. The seat belt brackets are pop riveted in place and a pieces of cake installing in a completed fuselage.

I don't have a harness yet, and don't want to buy one, as I'm probably a couple of years out from flying. Also, if the belt is looped through the fitting and sewn back on itself (Crow's are not), then the brackets will have to be spaced to allow room for the bracket and at least two thicknesses of belt.

Be sure to enlarge the hole in the crotch bracket for an AN5 bolt before you rivet everything in place. I had to buy a stubby threaded shank 5/16" bit for my angle drill to get the hole sized right. On the crotch belt strap fitting, just position the belt in the right place for the slot, then drill a new 5/16" hole in the metal fitting to align with the stock hole in Van's bracket. This way you get the advantages of having the correct location of the crotch strap to the bracket, and don't need any spacers or washers to fill the extra large hole in the Crow fitting. Do the same for the AN4 hardware where the lap belts connect.

I do plan to drill the brackets for the fitting bolt before I install the brackets. I haven't yet riveted the center fuselage together, so I'm trying to get every thing drilled before I start final assembly.

I'm a bit leery of drilling a new hole in the belt fitting. My plan is to relocate the holes in the brackets, then buy or fab a bushing to go between the fittng and the bolt. Bushing stock is only a couple of dollars at McMaster-Carr.

To make things easier I just swapped the end fitting on the crow harness to a standard triangular fitting. I didn't have to change any bolts, locations, or spacing. I happen to have had two end fittings laying around leftover from a cessna harness so it was no big deal.

Hmmm... I installed shoulder harnesses in my 170 nearly 20 years ago, and I didn't throw the old lap belts away, but it would probably take me days to find them...

Does anyone know if Crow or Hooker will send you a "test" crotch strap and hardware to get things sized up? I've already installed my brackets per the plans and I now a bit nervous that I'm going to be having problems when the day comes to install it.

That's why I got Fred Crow to send me the photo of the fitting with a ruler (post #1, this thread). He also mic'ed the fitting, so I have the thickness. With measurements taken from the photo, I can see that the hole in the brackets need to be about 1/2" lower than the pre-punched pilot holes so the slot in the fitting will end up centered in the rectangular holes in the brackets. If you've already drilled the bolt hole in the stock location, re-drilling or replacing the belt fitting might be your best option.


This whole exercise makes me glad I've spent the time I have in the build logs of those that have gone before me.
 
This whole exercise makes me glad I've spent the time I have in the build logs of those that have gone before me.

You were wise enough to know to ask the question. It never even crossed my mind to ask. Mine are in place using the Vans instructions. I'm in the middle of installing my flap actuator and don't feel like ripping the floors up again, just yet. When I get that done I'll measure and see where I am.
 
You were wise enough to know to ask the question. It never even crossed my mind to ask. Mine are in place using the Vans instructions. I'm in the middle of installing my flap actuator and don't feel like ripping the floors up again, just yet. When I get that done I'll measure and see where I am.

Thanks for the compliment Gil, but is wasn't so much wisdom as just reading ahead and learning from other builders.

As of this evening, my left set of brackets are drilled to the ribs and floors, using a screwed up aileron bracket and two thicknesses of the blue vinyl still on the strap brackets for spacing.

FP15012014A0004T.jpg
 
Miles your correct a little bit larger spacing will work but not much as the screw holes in the floor panels still have to screw into the flanges on the bracket and it was this putting in the screws that tightened up the angles around bracket,
To the point that the straps don't wiggle at all.
Jack
 
Yes, Derek and Jack, the forward bracket isn't rigid until the screws through the floor go in, due to the fact that the top half of the forward bracket has no rivets in the side flanges. I didn't realize that until I was fitting everything together last night. Before drilling ANY holes, I clamped everything together and clecoed the floor on, then marked the top flanges of the strap brackets through the screw holes in the floor. Everything was where it should be. If you increased the spacing to 5/16 like others have done, you'd have to relocate the screw holes through the floor for the top flange of the forward bracket, or bend the top half of the forward bracket back the top.:confused:

This took way longer that it should have due to some overthinking on my part, but at least it's right... I think.
FP15012014A0004U.jpg
 
crutch strap brackets

I'm building the fuselage centre section and want to install the crutch strap brackets, are they part of the fuselage kit or are they a separate order as I can't find them?
 
IHe also mic'ed the fitting, so I have the thickness. With measurements taken from the photo, I can see that the hole in the brackets need to be about 1/2" lower than the pre-punched pilot holes so the slot in the fitting will end up centered in the rectangular holes in the brackets. If you've already drilled the bolt hole in the stock location, re-drilling or replacing the belt fitting might be your best option.

You mean centered vertically, yes?

Because the pilot and co-pilot side holes are in different lateral locations to ensure the belts are centered horizontally on the seat (in line with the stick).

I assume you're just planning on drilling 1/2" *below* the appropriate holes...but just wanted to make sure you're not trying to center the fitting in both axes with the hole in the bracket...
 
I installed mine per plans, and the fit was really tight. It was tight enough that I now have to screw in the floor pan at the crotch strap bracket flange first, then pull it into place to get the rest of the screws in. It's a little annoying, but not bad.

I used AN960 washers pressed into the Crow bracket holes to accommodate the bolts. I put a bunch of them on a bolt chucked into a drill pressed and filed off some of the metal so the press fit wasn't too tight. Seems to be working fine.
 
You mean centered vertically, yes?

Because the pilot and co-pilot side holes are in different lateral locations to ensure the belts are centered horizontally on the seat (in line with the stick).

I assume you're just planning on drilling 1/2" *below* the appropriate holes...but just wanted to make sure you're not trying to center the fitting in both axes with the hole in the bracket...

My post is a couple of months old, but yes, I did mean centering the loop in the belts vertically in the cutout in the brackets. Here's what I ended up with:

Right:
FP06022014A0008E.jpg


Left:
FP06022014A0008F.jpg
 
In case anyone is getting tips from this thread in 2019, the Crow harnesses have evidently have changed a bit. It looks like older Crow crotch strap attach brackets were somewhat thicker than the 1/8" spacing that Vans calls out in their crotch strap kit, so I built mine 1/4" apart to be safe. And the mounting hole was bigger, causing builders to look for bushings to make them fit. Well, just got my Crows and lo and behold their attach brackets are 1/8" thick and the attach holes fit the AN5 bolt perfectly. Drop-in replacement now! Too bad I went through the trouble of adding extra space between the brackets. Looks like I'll be adding a couple of washers to ensure a tight fit.
 
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Ryan,

It's been a while, but I think I allowed extra thickness for the crotch strap too. I'd be interested in taking a look at your belts. What color and options did you get? I think I want the all black hardware but I was a little confused about some of the other options.

Ray
 
I got the same ones Garet reviewed (above): KAM LOCK RV6/RV7/RV9/RV14 AIRCRAFT RESTRAINT WITH PADS is the part name on Crow?s site. I?ll be back in town after May 8, happy to bring them by your hangar one day.
 
I recently bought my flying -7 it has I assume the Van?s 4 point system in it. Can the bracket hardware for the crotch be added?
 
I would think you could. The forward seat floor pieces can be removed to get access to that area. Some people put their comm antennae in that area so if the crotch mount isn?t there now that may be something to check out first.
 
Recommend it

I was copilot in a friend?s RV9A. Didn?t have crotch belt attached as we were Flying in smooth air. We hit some unanticipated rough air. My head hit the canopy fairly hard. Connected the crotch strap right away. Ever since I always connect my crotch strap. The thought of becoming incapacitated while flying is not very appealing.
 
I recently bought my flying -7 it has I assume the Van’s 4 point system in it. Can the bracket hardware for the crotch be added?

I added the RV7 5th point attach hardware to my RV6A no problem after RV6A already flying. Be careful when drilling through bracket flanges to ribs as bracket flanges are pretty soft and right angle drill bit can wander and enlarge hole if not careful. I also clecoed some 1/8 in. Thick Strips between front and rear brackets to maintain the proper spacing and alignment while drilling bracket flanges to ribs, which really helped. It also helped in drilling hole through both brackets for AN5 bolt with bracket not installed.
 
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I added the RV7 5th point attach hardware to my RV6A no problem after RV6A already flying. Be careful when drilling through bracket flanges to ribs as bracket flanges are pretty soft and right angle drill bit can wander and enlarge hole if not careful. I also clecoed some 1/8 in. Thick Strips between front and rear brackets to maintain the proper spacing and alignment while drilling bracket flanges to ribs, which really helped. It also helped in drilling hole through both brackets for AN5 bolt with bracket not installed.

Thanks for the info...
 
I would think you could. The forward seat floor pieces can be removed to get access to that area. Some people put their comm antennae in that area so if the crotch mount isn?t there now that may be something to check out first.


Thanks, I will check that out before going any further...
 
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