What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Adding a crotch strap

M5fly

Well Known Member
What does it take to add the crotch strap and where exactly does the mount go? I'd like to replace my belts soon with the kam-lock 5 point harness from Crow. I may also have to do a little modification to the mounts since the current belts use a hook and Crow bolts on.
 
I bought my plane built. It didn’t come with a crotch strap. I called crow and they sold them to me for $14 per. I removed the seat panels and the infrastructure, as well as the bolts, were already there. It took about 30 minutes total to install them. Easy as pie. The seat pan and the seat, both have openings for the strap to pass through.
 
I bought my plane built. It didn’t come with a crotch strap. I called crow and they sold them to me for $14 per. I removed the seat panels and the infrastructure, as well as the bolts, were already there. It took about 30 minutes total to install them. Easy as pie. The seat pan and the seat, both have openings for the strap to pass through.

My seat pan has a thin layer of fabric over it so I'll have to pull it up and see if mine has the infrastructure or not. I had assumed it didn't but maybe it does and that'll be easy.
 
Vans sells a kit to retrofit a crotch strap in their webstore.

5th pt. installation kit, RV-7/7A, RV-9/9A both seats CROTCH STRAP KIT $36.00

It will work in an RV-6/6A with some TLC.

Cheers!
 
On the 9A, the crotch strap for my Crow harnesses bolts between two cross stringers right behind the stick. I found the crotch straps to be a nuisance on my non-aerobatic airplane and never used them...removed both at condition inspection. Not hard to get to in order to install or remove as long as the floor is out.
 
I like the crotch strap. In flight, it keeps the lap strap low on my hips, and prevents it from riding up.
And in the event of a "sudden stop" it prevents "submarining", where you slide under your lap strap in a crash.
I see no downside. YMMV
 
Agree with Pete

The Van's kit for the -7 will work in the -6A. It did take some "field engineering and adjustment" to get it in. I agree the crotch strap is desireable.

Ron
 
Vans sells a kit to retrofit a crotch strap in their webstore.

5th pt. installation kit, RV-7/7A, RV-9/9A both seats CROTCH STRAP KIT $36.00

It will work in an RV-6/6A with some TLC.

Cheers!

I used the 7/9 kit on my 6A. I had to cut off one side and replace it with some angle (the seat rib spacing is a little bit different, but otherwise an easy mod.
 
I used the 7/9 kit on my 6A. I had to cut off one side and replace it with some angle

same on my -6.9. Easy to do is relative... I call myself experienced, but not sure if cutting off flanges, bending and riveting new ones, and fitting the whole thing whilst bent preaching is to be called easy :D

There are a couple of threads on here with similar info and a few more picts...
 

Attachments

  • Crotch.JPG
    Crotch.JPG
    196.6 KB · Views: 477
For those of you who have retrofitted a crotch strap into a flying RV6: how did you handle the already upholstered seat cushion?

It looks to me like the Van's kit would set the crotch strap coming out of the seat pan several inches aft of the control stick hole, necessitating a hole in the seat cushion.

Pictures I've seen of planes where the crotch strap was installed during the build, all have nice holes in the seat cushion done at time of upholstering.

Could you just run the crotch strap forward those few inches, under the seat cushion, and then pull it up in the notch in the cushion for the control stick.
 
For Cole, the OP, pictures I grabbed from either someone's build blog or a prior thread, I don't remember which.

FP01122012A0001D.jpeg

FP01122012A0001E.jpeg

FP01122012A0001F.jpeg

IMG_0228.jpeg

IMG_0229.jpeg

This picture shows the distance from the crotch strap exit, to the control stick hole I was talking about in my prior post.

IMG_0230.jpeg
 
Could you just run the crotch strap forward those few inches, under the seat cushion, and then pull it up in the notch in the cushion for the control stick.

You could but the strap would loose some of it's effectiveness in keeping the lap belt down and tight. Do you have an upholstery shop near that could advise you on installing a slit in your seat cushion?

The crotch strap is very effective in keeping you seated down & clear of the canopy in real bumpy air, but it must control the lap belt from movement to do this.
 
Thank you

For Cole, the OP, pictures I grabbed from either someone's build blog or a prior thread, I don't remember which.

View attachment 14093

View attachment 14094

View attachment 14095

View attachment 14096

View attachment 14097

This picture shows the distance from the crotch strap exit, to the control stick hole I was talking about in my prior post.

View attachment 14099

These are all extremely helpful! I'm glad the slit in the bottom seat cushion was mentioned too, I hadn't thought of that. Learning about your airplane and how to make modifications is half the fun of owning it.

I had the Crow kam-lock belts in my micro sprint years ago and loved them. If I can be comfortable strapped into a full-containment seat with a 5 point harness it'll be great in the RV.
 
You could but the strap would loose some of it's effectiveness in keeping the lap belt down and tight. Do you have an upholstery shop near that could advise you on installing a slit in your seat cushion?

The crotch strap is very effective in keeping you seated down & clear of the canopy in real bumpy air, but it must control the lap belt from movement to do this.

Not my experience. Mine come slightly from the rear then up, but do their job in keeping the lap belt positioned. My cushions have the U shape for the stick and are not square.
 
I did a retrofit for the crotch strap. Made my own parts. You will need to either modify the existing cushions or replace them with one with the slot for the strap. I had old cushions when I installed the strap and just cut a slot until I totally replaced my seat cushions.

By the way, install the bracket as far forward as possible without interfering with the flight controls. Vans shows them further aft then is comfortable for me. The strap shouldn’t actually contact your important parts.
 
For those of you who have retrofitted a crotch strap into a flying RV6: how did you handle the already upholstered seat cushion?

It looks to me like the Van's kit would set the crotch strap coming out of the seat pan several inches aft of the control stick hole, necessitating a hole in the seat cushion.

Pictures I've seen of planes where the crotch strap was installed during the build, all have nice holes in the seat cushion done at time of upholstering.

Could you just run the crotch strap forward those few inches, under the seat cushion, and then pull it up in the notch in the cushion for the control stick.

I made the piece instead of buying from Vans. I positioned it where the strap would exit the seat pan directly at the back of the U shaped cut out in the cushion. I had no slit in the cushion for the strap.

Larry
 
Adjustable Crow crotch strap

Has anyone tried making an easily adjustable length crotch strap for the 5 point Crow harness system? I fly with people that need a couple of cushions or booster seat and there is no way the center strap is long enough in those cases. I've thought about adding an adjustable strap but I don't know if Crow sells that separately. The other issue is that it just might be too bulky for that area. Any thoughts? Thanks.
 
Friction adapter hardware is adjustable and easy to use. (the center piece of hardware on these shoulder belts. A Three Bar Slide (top right piece of hardware in photo) is what is generally used on crotch belts and not easily adjustable.

An easy mod for someone with the right equipment, knowledge and materials. Maybe a parachute rigger in your area would be willing to help out.
 

Attachments

  • Seat belts copilot .jpg
    Seat belts copilot .jpg
    393.5 KB · Views: 258
Last year I replaced my old circa 2003 Hooker belts with new Crows. The old ones had friction slide adjusters just like the shoulder harnesses, and it was a simple mater to move them over to the new Crows (which as you noted do not include them.)

You should be able to find these adjusters for 2” belts. If Crow or Hooker don’t have them I’d start with a racing shop like Summit.
 
I like the crotch strap. In flight, it keeps the lap strap low on my hips, and prevents it from riding up.
And in the event of a "sudden stop" it prevents "submarining", where you slide under your lap strap in a crash.
I see no downside. YMMV

Exactly why I'm installing a 5 point in mine as soon as it gets home.

Regarding the latching mechanism, has anyone seen any research if one of these is better than the other? I've used the flip-over latch in the military and also have used the twist-off type when I flew civilian helicopters. Haven't decided which to buy yet.
 

Attachments

  • s-l1600.jpg
    s-l1600.jpg
    83.2 KB · Views: 56
  • s-l16002.jpg
    s-l16002.jpg
    534.3 KB · Views: 50
On the 9A, the crotch strap for my Crow harnesses bolts between two cross stringers right behind the stick. I found the crotch straps to be a nuisance on my non-aerobatic airplane and never used them...removed both at condition inspection. Not hard to get to in order to install or remove as long as the floor is out.

In the 18 months since I posted this, I've changed my mind. I don't know about the "submarining" concept, but the crotch strap does keep the lap belt flown about the lap and I'm reinstalling them when the floor next comes out for condition inspection.
 
I put RV7 crotch strap brackets in my RV6. It took some surgery because of seat pan rib separation variation, but not hard to do. The slit in my Cleveland made seats didn’t line up, but the notch in the seats for stick clearance works out just fine. If I used the slits in the seats for the crotch strap, I’d be speaking a few octave higher in turbulence. This setup works well for keeping the seat belts where I want them, and not “submarining” in the event of a quick stop.

909701F2-5307-47E7-BD85-F483756FF75F.jpg
 
Crotch strap....

Exactly why I'm installing a 5 point in mine as soon as it gets home. Regarding the latching mechanism, has anyone seen any research if one of these is better than the other? I've used the flip-over latch in the military and also have used the twist-off type when I flew civilian helicopters. Haven't decided which to buy yet.

I love my flip-over (h***-for-stout) Hookers. There is nothing like that reassuring CLICK when that lever is snapped into place. IMHO; there are many posters very satisfied by the Crow twist-off type. Personal preference. It is what I have always used. Cub has them as well.....

Anyone who doesn't think a crotch strap is necessary has apparently not flown through Wyoming. :D That 5th strap keeps the other 4 exactly where they need to be! Submarining? Don't plan on testing that out.....:eek:;)
 
Why Our Airplane Has Them

Read an accident report somewhere some years ago that said an RV-6 ended up landing in a mobile home park. It went as well (or as badly) as you’d expect. When the noise stopped, the pilot found himself in what remained of the baggage compartment. Not enough details to draw any strong conclusions but it seemed quite possible that he submarined right under the lap belt. Serious akro pilots, especially ones who pull a lot of negative g use crotch belts, sometimes called a negative g strap in that context. It helps keep the lap belt tight, along with the antisubmarine feature. Most auto race cars have crotch belts, too. I used Van’s kit for the attach fittings and tweaked it to work.
 
Yes a 5th point for me. Tested

I love my flip-over (h***-for-stout) Hookers. There is nothing like that reassuring CLICK when that lever is snapped into place. IMHO; there are many posters very satisfied by the Crow twist-off type. Personal preference. It is what I have always used. Cub has them as well.....

Anyone who doesn't think a crotch strap is necessary has apparently not flown through Wyoming. :D That 5th strap keeps the other 4 exactly where they need to be! Submarining? Don't plan on testing that out.....:eek:;)

I survived an 11.2 g crash about 6 months ago.
I contacted Crow to thank them for their product. It took all 5 to hold me in place and prevent further damage to my body.
I definitely do not feel comfortable with the lap belt riding up under my rib cage in flight.

Daddyman
 
IMHO; there are many posters very satisfied by the Crow twist-off type. Personal preference. It is what I have always used. Cub has them as well.....

My plane had the Crow twist-off locks when I bought it. It was apparent that if your hands are sweaty (or bloody:eek:), that smooth surface might be hard to grab hard enough to operate. Throw in a little wrist arthritis and those locks didn't really suit me. I was able to persuade Crow to sell me a couple of their lever lock as replacements...much better, IMHO.
 
Back
Top