Inatalling Vans Crotch Strap Brackets for Crow Harnesses

longranger · #1 01-12-2014, 04:06 PM

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?

jthocker · #2 01-12-2014, 07:02 PM

I just installed the same brackets in an RV 6, I used .125 spacing for the Crows and it worked out fine.

Smilin' Jack · #3 01-13-2014, 04:48 AM

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

jthocker · #4 01-13-2014, 06:29 AM

Quote:

Originally Posted by Smilin' 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.

longranger · #5 01-14-2014, 10:15 PM

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?

Dbro172 · #6 01-14-2014, 10:37 PM

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.

bruceh · #7 01-14-2014, 11:12 PM

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.

You can see how the lap belts are attached to the seat anchors here.

WingsOnWheels · #8 01-15-2014, 05:24 AM

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.

Lemmingman · #9 01-15-2014, 06:40 AM

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.

longranger · #10 01-15-2014, 09:53 AM

Quote:

Originally Posted by Dbro172

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.

Quote:

Originally Posted by bruceh

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.

Quote:

Originally Posted by WingsOnWheels

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...

Quote:

Originally Posted by Lemmingman

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.