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4 point vs. 5 point belts...

comfortcat

Well Known Member
:confused:

I'm planning on a 4 point seat belt system for my RV-9A. I have no intention of flying upside down, so I thought 4 point would be better for pilot and passenger.

My friend says he has heard of significant problems with the shoulder harness pulling the lap belt out of place when you tighten it down. He says it makes the lap belt ride on your stomach instead of low across your lap.

Are folks normally using 4 point or 5 point belts in the 9?

CC
 
I originally installed a 4 point but then decided to add the 5th point. Unfortunately, I already had my seats but they didn't have the slots in them for the crotch straps. So, I sent them back to get modified.

The Van's parts were pretty cheap.

I've never flown with a 4 point but I'm glad I went with the 5 point. Even with no acro, it's nice to be held snugly during turbulence.

If you're on the fence, at least have the crotch strap slots installed in your seats when they're first made.
 
I think you will find that there have been some injuries to people when they hit their head on the canopy during a roll over (flip). Since the shoulder straps are there to prevent you going forward not up the lap is what holds you down.
A five point harness help with this. I have five point in my 9.
 
The sub strap is really designed to keep the lap belt low, over your hips, in the event of an accident. If the lap belts slide up, it will harm your internal organs, possibly fatally.

The problem is that most people tighten their belts wrong. You should tighten the sub (crotch) strap first (if installed), lap belt second, finally the shoulder straps.

Yes, I have them in my -9. Hooker cam locks, thanks to my wife.
 
I have 4 point and am going to switch them out for 5 point. The lap belt is very difficult to keep low, and if I ever nose-over I won't stay in my seat. I always had 5 points in my cars and find them more comfortable. You can always leave the sub strap un-buckled and under the seat cushion if you want.

Those of you with 5 points - where are you attaching the sub strap to the air frame ?
 
...Those of you with 5 points - where are you attaching the sub strap to the air frame ?
Van's has a sub-strap anchor kit for the side-by-side models that I used. It basically bridges two the seat pan ribs. It is an easy retrofit and can be installed with pull rivets. You will have to cut slots in both seat pans to allow a place for the sub strap to pass through.
 
555555555555555555555555555555555555555555

Yep. Don't have the 5 point. Wish I did.
......always banging the canopy in my -9a, even with the lap super tite!
way easier to put in at least the anchor, than add later.
You can always choose not to connect it if you don't want it for some reason.
 
Safety Belts

I had 4 point in my 7 and could not keep tall people off my canopy in turbulence! Also had a very unsecure feeling, switched to 5 point asap. There is a reason almost all race cars/ boats/ planes... have 5 or 6 point. I went with Crow camlocks and am very happy. Simpson also has a very nice system. Hookers are also good but are VERY pricey. Be safe!
 
I flew the standard 4-pt harness for 14 years in the RV-6. Then one Saturday morning going into Moontown for breakfast I hit the worst turbulence I have ever experienced--for the first time I was concerned about what would happen if the latch popped loose and whether or not I would exit through the canopy. :eek:

Came home and ordered a G-Force 5-pt harness, the same one I've driven in the Stalker V6 kit car for ten years. It is a bit heavy but reasonably priced with a real latch that won't pop loose. Turbulence will still bounce the RV around but now I know I won't end up in the baggage compartment or take an unplanned excursion from the plane if a sleeve snags the latch.
 
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:confused:

I'm planning on a 4 point seat belt system for my RV-9A. I have no intention of flying upside down, so I thought 4 point would be better for pilot and passenger.

My friend says he has heard of significant problems with the shoulder harness pulling the lap belt out of place when you tighten it down. He says it makes the lap belt ride on your stomach instead of low across your lap.

Are folks normally using 4 point or 5 point belts in the 9?

CC

I think your friend is right. I fly with 4 pt harnesses in my 9A now and I always snug the lap belt tightly before snugging the shoulder harnesses, and the lap belt still rides up. Most passengers need an explanation just to use the 4 pt harness and don't seem able to grasp the finer points (like keeping the lap belt low) very quickly. FWIW, the 9A I'm building has 5 pt harnesses.
 
thinking of 5 point

I fly with the 4 point but try to snug up the lap belt. It tends to ride up if I snug the shoulder belts too tightly. I'm thinking of adding the 5 point at annual inspection and purchased the brackets four months ago.
 
What is the part number for the bracket kit?

Thanx everyone! I guess the 5 point is a good idea! I just want to get a light one.

I fly with the 4 point but try to snug up the lap belt. It tends to ride up if I snug the shoulder belts too tightly. I'm thinking of adding the 5 point at annual inspection and purchased the brackets four months ago.
 
4-point

I stuck with the 4-point because it worked so well for me over 2000+ hours in the F-4. We just always cinched up the lap belt first, then the shoulder harness. Also, the absence of a center cinch belt meant we had access to our bits and pieces when we needed to use the piddle pack on long-duration flights.

Now, I hope this plan works, because N260KM is still under construction. Time will tell.
 
FS--5 Point

Took out Vans 5-Point and replaced with Crows. Make me an offer on the Vans. Two sets, black, but the crotch strap is red.
Mark
 
4 vs 5 pt

A concern with the 4 point is "submarining" when the hips slide forward as the lap belt rides up. Knees can hit interior parts and the lap belt can damage internal organs as mentioned before. The shoulder straps become loose and allow forward movement, the head may impact the panel or glare shield, and spinal compression fractures can result. Think there's a reason that fighters, race cars and aerobatic airplanes have the 5 point? You may never miss the crotch strap if you fly upright in smooth air and experience no severe frontal impact. In other cases you'd be grateful for that 5th strap. I am putting them in and hope you all consider them.
 
After flying around in the real bumps out west for the past year, I'm thinking more than ever of retrofitting the RV-6 with 5-points when we move it out here next month - already have them in the -3 and the -8. I like to be well-connected with my machine....
 
I've flown a variety of aircraft with 4 and 5 point harnesses. I would go with 5 points because of all the reasons above. They are much more secure and keep the belts where they belong. 4 points will ride up, especially if your shoulder straps have inertia reels.
 
I've flown a variety of aircraft with 4 and 5 point harnesses. I would go with 5 points because of all the reasons above. They are much more secure and keep the belts where they belong. 4 points will ride up, especially if your shoulder straps have inertia reels.
 
Is it possible to have a 5 point harness in the front seat of a 10?

The back has all of the attachments, but I'm not sure how you'd handle the crotch strap up front.

David
 
There are many good reasons why 4 points aren't legal in race cars. If ever you really need them...a 4 point can kill you. I'd rather leave the constant speed prop off than the anti sub belt.
 
A Safety perspective

I'm replacing my 4pts with 5 at the next opportunity.

Sam's post got me thinking, and I checked the link to the SEMA safety foundation document on
installation, maintenance, and operations of (driving) safety belts.

Two items caught my eye:

"...Restraints must be maintained, inspected, and replaced or rewebbed
every two years because they degenerate from exposure to the elements and over time.
Prolonged exposure of seat belt webbing and thread to sunlight can cause degradation of
the fibers and loss of restraint integrity.

"...The webbing used in motorsports restraints is typically made with DuPont Nylon
6-6 or a similar product. According to the data, the webbing loses about half of its strength in
one year. With this kind of rapid deterioration, it is obvious why
replacing the webbing every two years is essential to driver safety..."
 
I am sure somebody can find some real world example showing death or injury could have been avoided in an aircraft accident if a crotch strap was in place vs 4 point?
Anybody?

5 point are much more comfortable, and, theoretically, safer. However, I have never seen any actual examples of it. Let's face it. Most accidents have two outcomes. Those that walk away with very little injury regardless of equipment, and those that didn't stand a chance too.

Let's not compare race car driving to flying airplanes. If we do, lets compare the hundreds of passenger cars that crash everyday. I have never seen a passenger car with a crotch strap.

That said, I wish I had them in my RV. That is on my upgrade wish list.
 
Thanx Jon.

I think the point here is the way the seat belt is attached and the way you sit in a 9. My Skyhawk had 3 point belts and they were fine. The seat was high and the lap belt could be fastened low across the lap with no problem. And yes, you can ask me how I know a three point belt can save your life.

The 9 is different, where you actually sit on the floor. The extra belt is to position the lap belt, not really to supply more restraint. At least I HOPE not! OUCH!

OK, OK, a 5 point for me!

Dkb


I am sure somebody can find some real world example showing death or injury could have been avoided in an aircraft accident if a crotch strap was in place vs 4 point?
Anybody?

5 point are much more comfortable, and, theoretically, safer. However, I have never seen any actual examples of it. Let's face it. Most accidents have two outcomes. Those that walk away with very little injury regardless of equipment, and those that didn't stand a chance too.

Let's not compare race car driving to flying airplanes. If we do, lets compare the hundreds of passenger cars that crash everyday. I have never seen a passenger car with a crotch strap.

That said, I wish I had them in my RV. That is on my upgrade wish list.
 
I stuck with the 4-point because it worked so well for me over 2000+ hours in the F-4.

How many crashes in that time? The only reason to have a crotch strap is to keep the lap belt low when your body is thrown into the shoulder harness during a crash. In flight and absent crashing, even the shoulder harness serves no real purpose. Despite widespread beliefs, shoulder harnesses don't even serve a purpose for aerobatics...exept in airplanes that have extreme reclined seating (Giles, MX). Then they help keep your torso in place during negative G. So aside from crash considerations, a 2-point (lap belt) is all you need in any airplane. Once you consider crashworthiness, I know of no arguments against a 5-point being better.
 
I am sure somebody can find some real world example showing death or injury could have been avoided in an aircraft accident if a crotch strap was in place vs 4 point?
Anybody?

5 point are much more comfortable, and, theoretically, safer. However, I have never seen any actual examples of it. Let's face it. Most accidents have two outcomes. Those that walk away with very little injury regardless of equipment, and those that didn't stand a chance too.

Let's not compare race car driving to flying airplanes. If we do, lets compare the hundreds of passenger cars that crash everyday. I have never seen a passenger car with a crotch strap.

That said, I wish I had them in my RV. That is on my upgrade wish list.


Not comparing RV's to race cars, but if you're looking for that data...the race car world has it...and a lot of it. Nothing at all theoretical about it. 5 points are much safer.
 
How many crashes in that time? The only reason to have a crotch strap is to keep the lap belt low when your body is thrown into the shoulder harness during a crash. In flight and absent crashing, even the shoulder harness serves no real purpose. Despite widespread beliefs, shoulder harnesses don't even serve a purpose for aerobatics...exept in airplanes that have extreme reclined seating (Giles, MX). Then they help keep your torso in place during negative G. So aside from crash considerations, a 2-point (lap belt) is all you need in any airplane. Once you consider crashworthiness, I know of no arguments against a 5-point being better.

You may be correct...theoretically...but I have found being able to cinch the shoulder harness down tight because the crotch belt is keeping the lap belt in place really allows me to stay connected to the seat during turbulence (and my head off the canopy)...more so than without the crotch belt.

The turbulence I encountered that prompted the installation of the 5-pt racing harness felt a lot like a two-minute crash...... :eek:
 
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Not comparing RV's to race cars, but if you're looking for that data...the race car world has it...and a lot of it. Nothing at all theoretical about it. 5 points are much safer.

...only when you need them ;)
It makes sense, but, sadly, as with many safety discussions here, nobody can produce any real life statistics that they save lives or prevent injury in aviation accidents...., yet....
 
True enough. I haven't seen any real life proof that harnesses are safer than tying myself to the seatback with a ratchet strap either...but none the less....they are. ;-)

Cheers
 
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I believe a guy landed short of our field a number of years ago. Think he had on a 4-point. Somehow he ended up in the baggage area of his RV-6.
 
I believe a guy landed short of our field a number of years ago. Think he had on a 4-point. Somehow he ended up in the baggage area of his RV-6.

I believe a guy landed short of our field a number of years ago. I think he had a 5-point. Somehow, he no longer can bear children..... ;)
 
Repeat seating

If you have a 4 point you may have noticed you can't jump back in after a flight and just buckle up again. It seems odd, but my 9A always requires loosening the shoulder and pull the lap tight and low. Then reset the shoulder. If firmly on the pelvis as designed, they do the job. If your pelvis is nowhere to be found, you might need additional work. 5 point conversion on the list, but for now proper adjustment is key. Also tug the pax before taking the runway. Usually fitted wrong. You owe them the extra effort.
 
Does anybody use inertia reel sholder straps? I find that fixed sholder straps tend to keep me from reaching some things in the cockpit unless they are left loose enough to make me nervous.
 
Hey Jack I hear you. I used to have that problem in a few older certified aircraft. However in just now 70 hours, I bet I have only had to loosen my straps to reach something in the RV twice. I keep them snug and everything in the RV seems to be in reach. In the old 172 I trained in you just always left them loose.
 
I ordered and received the crotch strap kit from Vans and have dry-fit it into my 6 (I ordered the 7/9 kit). It looks like everything will fit fine and is only a few hour job. - This has been on my wish list, but it took this thread to get me to take action.
 
I just installed the Vans kit in my 6 in Jan. It took me more than a 'few' hours ;-) I had to modify/narrow the brackets to fit between the ribs. You'll definitely need a 90deg drill to get into those tight spots.
...and I love it! Much more comfortable with the belt snug across the hips and much more secure fore acro. My wife gives it two thumbs up as well.
 
Where did you position the sub strap hole (6 has different dimensions), and did you cut a hole in your seat cushion for it, or do you run it up to the stick cut-out? - Any photos? I have been looking for a 90 drill that will fit in there. The best I have seen is an adaptor.
 
I bought van's 5 pt because of the price. I have hated them for 17 yrs now! that buckle will pop loose many times, and I've had just one passenger figure out how they work on their own. it's not a huge deal [or I would have bought new ones], but I'd think hard about other brands.
 
I bought van's 5 pt because of the price. I have hated them for 17 yrs now! that buckle will pop loose many times, and I've had just one passenger figure out how they work on their own. it's not a huge deal [or I would have bought new ones], but I'd think hard about other brands.

also, remember that the belts are going to show in the reflection of your GPS, so black is a best choice.
 
... the fit is crucial!

This is really interesting.... I have a 4 point, and tried a simple trial run, just adding another of the shoulder harness buckles, to simulate the crotch strap link.
So with 3 links, I could just barely get the buckle to click, but not reliably, or every time. My first thought was, ' there's NO way I can trust a passenger to do this!' so I gave up the idea of McGyvering a 5th point onto that setup.
I was sure that the Van's 5 point set must have a longer spade on the lap belt, to accommodate the 3 links....apparently, it's still a pretty tight fit!
 
I currently have Oregon Aero foam w/ no cutouts. However, the crotch strap runs in front of the seat w/ very little deflection and holds everything fine. I have Classic Aero seats on order that do have the strap cutout.

The location of the seat pan nut plates really determines where the cutout will be. One of the shots will show how I cut down the strap mounts and riveted on new angle to narrow the mount between the ribs.

And yes, the 5-point buckle 'tang' is longer to accommodate the extra strap.

D415C1BF-14FD-4BB3-B826-109E96BBF44F.jpg

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A6398CAD-16BB-43A0-9BB8-42A75CF35278.jpg
 
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Great thread! I'm taller than average, so I'll definitely go with the 5-point to keep me from hitting the canopy. It happened a couple of times during training (DA-20) when I didn't have the belts snugged down enough, and they were 4-points. The thought of being knocked unconscious in turbulence sends shivers down me spine?.aaargh!
 
I haven't flown it yet, but last night I did installed my new 5-point harnesses and tried them on - Wow. What a difference in where the lap belt rides. I knew it would help, but did not expect it to make that big of a difference. I actually feel like I am being held down in the seat. This has been on my wish-list. I just needed this tread to give me the push. I installed 2" webbing because it seems less intrusive. My rationale is that the anchor points are not all that strong, so I have twice the shoulder restraint area of a car, with much lower potential force.
 
bracket and straps

Today is th 2nd time in a month I hit rough air. With lap belt tight my wife and I both kit the canopy, just today. It was frightening and came outta no where. The other time hurt my neck. Where do I buy the 5 point and whatever brackets? Also, what kind of job installing these other brackets? I'm reading through here on my phone and may have missed the info I'm looking for. Thx DM
 
I also extended the seat back for the pilot to make a head rest. I have read that often people die from whiplash after an accident. Maybe this is why all cars have headrests. I did t put one on the passenger seat, sorry honey, so access to the luggage isn't totally restricted. I rarely have a passenger anyway.
 
I also extended the seat back for the pilot to make a head rest. I have read that often people die from whiplash after an accident. Maybe this is why all cars have headrests. I did t put one on the passenger seat, sorry honey, so access to the luggage isn't totally restricted. I rarely have a passenger anyway.

Whiplash injuries in cars are caused by being hit from the rear, flinging the head backward. Not a big chance of that happening in an airplane.
 
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