M4 Shoulder Harnesses

Redhawk · Post by **Redhawk** » Sun May 11, 2014 9:20 am

Talked to Maule to find out that a pair of front seat inertia reel shoulder harnesses are about $1500! Ouch!
Looking for any good ideas on less expensive alternatives!
Thanks out there!

st8cop166 · Post by **st8cop166** » Sun May 11, 2014 9:47 am

Good luck with that. I researched and tried to get other inertia reel seatbelt manufacturers to work with me. If I was flying an Experimental, it wouldn't be that difficult. For a certificated aircraft, they just won't work with you. I ended up buying the attachment hardware from Maule and then order the harnesses later. After ordering them, I've been waiting about 3 months now I think for them to come in. Set back $100 a month and you can have them paid for by the time they show up.

akholland · Post by **akholland** » Mon May 12, 2014 9:21 am

If only they would be honest when you order and tell you it's goona be a year before u get them.... My plane came with a set. I would gladly sell them for 1500 bones! That's nuts

pilot · Post by **pilot** » Mon May 12, 2014 11:58 am

The best alternative IMO is a "pull-to-tighten" shoulder belt. Light wieght, no parts to fail.

crbnunit · Post by **crbnunit** » Mon May 12, 2014 1:38 pm

Aimsafe? Hooker? There are other options for a fraction of that cost!

st8cop166 · Post by **st8cop166** » Mon May 12, 2014 5:18 pm

I tried those but they are not STC'd for Maule's. You might be able to get around that with a broad interpretation of the Circular (I think that's what it was) that the FAA put out. The critical piece of it is the attach brackets to the airframe that the shoulder harness attaches to. I did not want to scrimp with that piece of it but could not find a shoulder harness that would fit it and AMSAFE wouldn't sell me one. I'm guessing here, and could be wrong, but I think the ones Maule orders are from AMSAFE. That's just based on what I've seen. Maybe someone with installed shoulder harnesses can confirm that.

Redhawk · Post by **Redhawk** » Mon May 12, 2014 5:23 pm

Would it work just to wrap the strapping directly around the horizontal tubing under the headliner?

riverbuggy · Post by **riverbuggy** » Mon May 12, 2014 5:44 pm

I retrofitted my M4 with the Maule shoulder harness kit. They are Amsafe.
The kit includes the lap belts as well to match the shoulder harness. IMHO; don't skimp here! However, that being said: "anything is better than nothing".

gbarrier · Post by **gbarrier** » Mon May 12, 2014 5:53 pm

The other vendor, Davis Aircraft will sell to you or at least they gave me a quote a couple of months back for a pair for the back. The part # for those were FDC-6400-568-3. I don't remember the quote but it was nothing like what you were quoted. I doubt the front belts are the same P/N as the length is probably different but if you can get it you might email them at DavisAircraft.com. You will need the part number. There's a couple of threads on this forum where people have listed some part number if you hold your mouth right when you search. I'm not real good at that.

I really like Hooker pull to tighten at a fraction of the price and bet a good IA could get a field approval for them to wrap around the overhead bar and buckle. The Hookers in my champ do that but as I remember they were approved for the application.

st8cop166 · Post by **st8cop166** » Mon May 12, 2014 5:54 pm

I'm with Riverbuggy. I wouldn't scrimp on the attach brackets and I certainly wouldn't wrap the belts around it. Not sure how you would do that anyway. There are some tremendous forces at work in a crash and if you are going to spend the money to make it safer, I'd go with what's been tested. Probably a lot of opinions out there on that but the brackets are supposed to be "engineered" to hold up. Riverbuggy is also correct when he says anything is better than nothing and that's kind of the message sent by the FAA circular. I have that thing somewhere. I'll see if I can find it and post it.

Redhawk · Post by **Redhawk** » Mon May 12, 2014 6:17 pm

Got a quote request out to DavisAircraft....
Will pass along what I find out!

st8cop166 · Post by **st8cop166** » Mon May 12, 2014 6:32 pm

In case you get bored, here's some light reading:

http://www.faa.gov/documentLibrary/medi ... C21-34.pdf

http://www.pierceaero.net/techdata/rsh.pdf

The second document is the one I've been referring to. There is quite a bit of forum traffic on this at www.shortwingpiper.org.

Redhawk · Post by **Redhawk** » Mon May 12, 2014 6:53 pm

Thanks a bunch for those references!
My takeaway is that my older M4 is a candidate for a retrofit, and as long as there are no structural changes to the airframe that adding a shoulder harness possibly by a clamp or something on the cross tube is a "minor change" and simply requires a logbook entry.

st8cop166 · Post by **st8cop166** » Mon May 12, 2014 7:02 pm

I think you're right, but don't take my word for anything. I'm trying to post some photos of my attachment brackets. PM me your email address and I'll send the photos to you. I'm apparently not smart enough to figure out how to add photos to the forum. If they will fit your M-4, it might make your system safer.

Andy Young · Post by **Andy Young** » Mon May 12, 2014 8:16 pm

As far as wrapping the belt around the frame tubes goes, if you think about it, nothing could be stronger than belt direct to frame. Anything else (brackets, etc.) add a link between those two. So that added piece could be either weaker or stronger than the tube, but in the end, all the force goes to the tube anyway, so the total system (with bracket) can be as strong or weaker than the direct wrap, but can not be stronger. Of course, brackets usually make for a cleaner installation.

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