Seat Belts and Restraints

[Bcone1381]

This might be a good time to talk about seat belts and shoulder harnesses.

I think I desire a five point harness, with the shoulder straps that retract for the front seat. I've found some 4 point Schroth products on ebay. What are people installing, and do we have any feedback from folks who have installed and maybe even depended on them for there safety? Suppliers?

Brooks

[zkelley2]

And where are people mounting the shoulder straps? The bar that comes across the top behind your head seems like it would bend in a crash.

[Archer39J]

Without looking too much into it. What, maybe 100# torso, say 9G fwd, 2X for passenger = 1800lbs on that bar. Yeah might bend a bit, probably wouldn't break though. Have to do an actual analysis to be sure but I'm eyeing it as a harness attach point myself.

[Mark Goldberg]

Scott at Hooker Harness is who I send builders to. Hooker offers a lot of options, and they give a discount to BH builders. Mark

[S Lathrop]

I will add my recommendation for Hooker as well. What I wanted was based on my years of racing and doing an occasional testing of the harness setups I had in my cars. They built the exact system I wanted.

One suggestion I would make is that you think of a 6 point system. I installed 6 point systems in my cars. There were 2 straps that went from the buckle under both legs znc were mounted to the back of the seat. The driver actually sat on the belts. Think a parachute harness for the 2 straps between your legs. Done right it is very comfortable and really gives the restraining effect that you hope never becomes necessary.

The one thing I am not happy with is where I had to mount the shoulder harness. I have it just above the rear seat . The inertia real is above the ceiling. While it will work well to prevent forward movement of the upper torso, it won't help hold the pilot in the seat. I toyed with adding straps that would go from the floor, over my back and be in front of the seat back. These straps would add a restraint in the vertical direction which the shoulder harness does not do. The straps would attach with the shoulder harness. I can see something like this as helping in severe turbulence. But I

[JimParker256]

Be careful with any straps looping over the shoulder and down down behind the seats. In a forward collision, the torso is thrown forward, and the belts over the shoulders can cause spinal compression – not a good thing! About a 45-degree angle from the shoulders to the ceiling is ideal, from what I learned.

[S Lathrop]

Be careful with any straps looping over the shoulder and down down behind the seats. In a forward collision, the torso is thrown forward, and the belts over the shoulders can cause spinal compression – not a good thing! About a 45-degree angle from the shoulders to the ceiling is ideal, from what I learned.

Now you know why I did not do this. But shoulder belts that mount above the shoulder are not good at preventing upward motion of the person being restrained. I have a helmet with a skid mark from the track when I went on my head. The recommended mounting for a shoulder harness in a race car is perpendicular to the driver's spine.

[alaskabearhawk]

Cars have different force vectors in a crash than an aircraft. https://www.faa.gov/documentLibrary/...r/AC_21-34.pdf

[AKKen07]

For anybody who is curious and deliberating about seatbelt mounting points: I just had my wife sit in the front pax seat and measured a 45 degree angle from her shoulder referencing the longitudinal axis of the fuse as per the article linked by alaskabearhawk above.
(“Again, a 45 to 55-degree belt angle relative to the longitudinal axis or the aircraft is most appropriate. This angle permits the safety belt to react to the upward pull of the shoulder harness. The shorter safety belt length in this figure also reduces stretching for better control or occupant movement.”)
That angle intersected the lateral bar to which Bob’s seatbelt tab is attached. Granted my wife and I are both on the tall side, average and shorter people would prefer a point farther aft. 55 degrees for us would be forward of that bar.

[Bcone1381]

Are you guys using inertial reel to retract the shoulder straps? I'm thinking an inertial reel for the front seat might help accommodate pulling the first notch of flaps, but maybe I am over thinking this and the adjustable shoulder strap is fine. I suspect we get use to whatever we install after a short time.

[Archer39J]

I've always been pretty well restrained when the lap belt was snug. Still undecided whether I want a regular shoulder belt or a harness.

[S Lathrop]

Here are pictures of how I mounted the shoulder harness and inertial real. For me this was the best I could think to do. I can sit in the rear seat but the harness mount is a bit close for real comfort.

The bracket holding real is designed so that the forces on the belt are in line with the mounting point. The real actually moves a bit in the mounts to stay aligned with the belts and the occupant..

[Mark Goldberg]

I think an inertial reel for the pilot is a must have. To reach flaps and fuel selector valve. FYI - it is on the checklist of any inspector or DAR that the pilot be able to reach everything without taking off the shoulder harness. Mark

[whee]

IMO, a shoulder harness is a must even if the mounting angle isn't ideal. I was unwilling to compromise the head space over the rear seats since mine is a family airplane. I mounted my reels to the rear carry through tube which is plenty beefy for a harness mount. The angle is steeper than desired and not ideal but it is better than nothing. I sit far enough forward that the harness angle is close to the 45* max angle.

schu has the best harness solution I've seen.

I bought some Schroth harnesses off ebay and they are awesome. Best harness I've ever encountered in an airplane. I put them in all seat positions.

[zkelley2]

I really like the 5 points we have in the big planes. The one going down keeps the lap belt from riding up with the inertial reels and also keeps you from sliding out the bottom.

[jaredyates]

I was really glad to find some military surplus Amsafe 5-point buckles like what we see in the big planes. The only feature they don't have is the lever to release just the shoulder straps.

[quadra]

I really like the 5 points we have in the big planes. The one going down keeps the lap belt from riding up with the inertial reels and also keeps you from sliding out the bottom.

Jared could you please post a picture or model number of the buckle or system? I did a quick google image search and could not find anything.

edit: I misunderstood and was thinking the shoulder harness straps could be detached from the lap belt - I see now that there are several models that allow the shoulder straps to be either inertia reel activated or locked by engaging a remote lever... very nice option!

[zkelley2]

Those levers are... something.

It's a nice joke to flip the lever on the FO just after he put's his seat belt on. Starts pulling and releasing like the inertia reel locked up, takes 30 seconds for a new guy to figure out!
Or do the same before top of D, they go back to grab the shoulder harness and it won't move. If they're really a FNG, they might think it's broke and they have to land without!

[schu]

IMO, a shoulder harness is a must even if the mounting angle isn't ideal. I was unwilling to compromise the head space over the rear seats since mine is a family airplane. I mounted my reels to the rear carry through tube which is plenty beefy for a harness mount. The angle is steeper than desired and not ideal but it is better than nothing. I sit far enough forward that the harness angle is close to the 45* max angle.

schu has the best harness solution I've seen.

I bought some Schroth harnesses off ebay and they are awesome. Best harness I've ever encountered in an airplane. I put them in all seat positions.

I welded in a new tube parallel with the rear spar carry-through that is about 7" behind the spar carry-though. I then mounted my inertia reel on the spar carry-though facing aft, and the webbing wraps around the new tube to the pilot and co-pilot.

Here is why I did that:

1. The angle from the spar carry-though is too steep to be correct according to AC_21-34 that Paul posted above. With the additional tube, the angle is way better.

2. By putting the reel above the spar carry-though I can hide it in the headliner.

3. The reel isn't right above the rear passengers head nor is the webbing totally in their space.

4. The new tube might deflect in a crash, but the load is tension/deflection and if I hit hard enough to bend it, I probably want it to give. I don't think a seatbelt would be able to sheer it, and if it does, I'm not going to live to tell about it.

5. The Schroth stuff is nice, and it's cheap.

6. It adds minimal weight. I know that there is a lot of desire to not add weight to the airplane, but my 4-point setup and extra tube is only 1-2lbs, and it's a very worthwhile 1-2lbs.

Here is a link to the belts I put in my airplane:

https://www.ebay.com/itm/Schroth-Military-Vehicle-4-point-Restraint-System-Seat-Belt-with-Retractor-NEW/272162965992

[Mruffatto]

Schu did you put those same belts in the back too?

[whee]

I welded in a new tube parallel with the rear spar carry-through that is about 7" behind the spar carry-though. I then mounted my inertia reel on the spar carry-though facing aft, and the webbing wraps around the new tube to the pilot and co-pilot.

Here is why I did that:

1. The angle from the spar carry-though is too steep to be correct according to AC_21-34 that Paul posted above. With the additional tube, the angle is way better.

2. By putting the reel above the spar carry-though I can hide it in the headliner.

3. The reel isn't right above the rear passengers head nor is the webbing totally in their space.

4. The new tube might deflect in a crash, but the load is tension/deflection and if I hit hard enough to bend it, I probably want it to give. I don't think a seatbelt would be able to sheer it, and if it does, I'm not going to live to tell about it.

5. The Schroth stuff is nice, and it's cheap.

6. It adds minimal weight. I know that there is a lot of desire to not add weight to the airplane, but my 4-point setup and extra tube is only 1-2lbs, and it's a very worthwhile 1-2lbs.

Here is a link to the belts I put in my airplane:

https://www.ebay.com/itm/Schroth-Mil...W/272162965992

We need a pic of this tube welded in place. It is the solution I wish I had gone with.

Those Schroth belts are awesome. They are what I installed in my plane I’m thrilled with them.