shoulder harness??

redneck · Post by **redneck** » Sun May 10, 2009 7:58 pm

1.) I have a '92 MXT7 with the factory shoulder/lap belt configuration. How difficult is it to install a inertial reel shoulder harness, presumably mounted to the overhead rib behind the pilot's head? Who supplies? Cost? How difficult to install? Recommended?
2.) My current belts no longer fully retract into the reels. It seems that the fabric has gotten slightly thicker with wear and won't fit onto the reel. This leaves excess belt loose and flopping around, and it's no longer a secure fit in case I actually need it. Any suggestions about cutting off a portion (way more belt than needed at present) of the belt so that it'll fully retract on the reel, and then restitching it securely somehow?
Question 2 is part of the reason for question 1. I need to do something different from what I got now.
3.) Local CAP plane is also a MXT7 that has a shoulder harness installed. I understand that it's not real comfortable. Any problems with the straps on the shoulder harness worrrying the sh@? out of your neck?

a64pilot · Post by **a64pilot** » Mon May 11, 2009 4:24 am

Hey redneck, I need to come to Dalton this week and have the 4way seat belts and can let you take a look if you can give me a ride into town

.
I don't like them and think they are a waste of a lot of money for a couple of reasons, one you have a tendancy to submarine a 4way, and they are so uncomfortable, I won't wear them, so I really only have a lap belt now, and three way is better than a lap belt.
I would replace your belts, I wouldn't cut them shorter as they may not be up to the task if they are so worn that they won't retract now.

Kirk · Post by **Kirk** » Mon May 11, 2009 6:19 am

I agree that a 4 point is a waste of money. In an impact the body tends to "submarine" under the lap belt which is pulled up.

I've got 3 points in my M5, but really would prefer a 5 point, since that is the ultimate protection. Rigging a crotchstrap to the seat seems doable but getting an FAA sign off may not be...

A64, if your fuselage has the 3 point fittings it's a simple install and David Wright got me a very good deal on them.

Kirk

belandd · Post by **belandd** » Mon May 11, 2009 11:07 am

In the interest of safety, the FAA has established a very liberal policy concerning seatbelts.

You may only need a log book entry.

I think there is some information posted on their web site concerning this. I know that I received a letter from the FAA some time ago outlining their position.

What it amounts to is simply that any seat belt shoulder harness combination is better than none and so the approval process should be as easy as possible.

crbnunit · Post by **crbnunit** » Wed May 13, 2009 11:34 am

If it were me, I'd probably just get your belt system repaired. There are several companies that will re-belt your reels for cheap. Much less expensive than a whole new system. I researched all this not long ago. Wish I had saved some links. A simple Google search pulled up all of my hits though.

belandd · Post by **belandd** » Thu May 14, 2009 8:59 am

Plenty of listings for seat belt repair in Trade A Plane

donknee · Post by **donknee** » Sun Nov 22, 2009 3:37 pm

I have the original lap belts and I'm looking for some 3 point belts with the retractable. I checked and it appears there is the threaded fasterner above the door post. Does anyone have some good used ones for sale? I checked with Bryan at Maule and he can get me some new ones.
Thanks, Don

rbowen · Post by **rbowen** » Sun Nov 22, 2009 6:45 pm

Somewhere I read the following "safety" of seat belts (in order of DEcreasing safety):

5-point harness (the best)
3-point harness (i.e., across the torso)
4-point harness (submarining is why these aren't good)
seatbelt only

I have four-point belts in mine, and find them very uncomfortable (as A64pilot said) because the anchor points for the shoulder belts are basically straight up, and the belts rub on the back of your head all the time.

My strong preference is for a three point set-up, with an inertia reel on the shoulder harness (just like your car).

alaskaflyer331 · Post by **alaskaflyer331** » Mon Nov 23, 2009 2:28 am

belandd wrote:In the interest of safety, the FAA has established a very liberal policy concerning seatbelts.

You may only need a log book entry.

I think there is some information posted on their web site concerning this. I know that I received a letter from the FAA some time ago outlining their position.

What it amounts to is simply that any seat belt shoulder harness combination is better than none and so the approval process should be as easy as possible.

http://frwebgate.access.gpo.gov/cgi-bin ... 0_register

The FAA does not encourage the
approval of retrofit shoulder harness
installations as minor changes. The
preferred methods of approval are
Supplemental Type Certificate or Field
Approval. However, the FAA should not
forbid the approval of a retrofit shoulder
harness installation as a minor change
in:
· The front seats of those small
airplanes manufactured before July 19,
1978, and
· In other seats of those small
airplanes manufactured before
December 13, 1986.
A retrofit shoulder harness
installation may receive approval as a
minor change in these small airplanes if:
· The installation requires no change
of the structure (such as welding or
drilling holes).
· The certification basis of the
airplane is 14 CFR part 23 before
Amendment 23–20, part 3 of the Civil
Air Regulations, or a predecessor
regulation.

chazdevil · Post by **chazdevil** » Wed Dec 02, 2009 9:49 pm

Recently installed the three point inertia reel system. A+. Had the four points in the old Stinson and these are way more comfortable.
Passengers like them also.

gear · Post by **gear** » Sun Dec 06, 2009 7:59 am

sorry for my ignorance,.... can someone explain to me the "submarining", im not following that.

I have an M-5 and it has the shoulder straps anchored to a common point behind the seat on the floor. Is this considered the 4 point? I'm not real happy with them.

There are two holes in my fabric liner where the shoulder harness would go - I should look behing the fabric to see if the fittings are there.

garth

MauleWacko · Post by **MauleWacko** » Sun Dec 06, 2009 8:38 am

rbowen · Post by **rbowen** » Sun Dec 06, 2009 11:54 am

"Submarining" is the term for what can happen without a crotch strap. Without that fifth restraint, the upper body pitches forward, the inertia reels lock, the shoulder harnesses then pull up on the lap belt, and the body slides down and out from under the lap belt (thus "submarining"). This frequently results in severe internal injuries to organs in the lower torso.

The crotch strap stops the lap belt from rising, and the body can't escape under the lap belt.

brokenaero · Post by **brokenaero** » Sun Dec 06, 2009 8:58 pm

If the crotch strap stops all that energy...................well you and the twins might have wished there was submarining instead.

crbnunit · Post by **crbnunit** » Mon Dec 07, 2009 1:16 am

Um, yea. The crotch straps have to be well located and tight or things can get ugly.

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