Backcountry Pilot • FAA approved Carabiner? Shackle?

FAA approved Carabiner? Shackle?

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Mon Feb 25, 2019 3:58 pm

FAA approved Carabiner? Shackle?

Looking for options for attaching my passenger seat belts to the l-track rails.

My seat belts have this style of ends:
Image

I planned to used this style of l-track stud:
Image

Some type of carabiner or shackle would work but I can't determine if any are FAA approved which they need to be for the DAR to accept the installation.

Any ideas?
whee offline
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Mon Feb 25, 2019 4:00 pm

Re: FAA approved Carabiner? Shackle?

whee wrote: if any are FAA approved which they need to be for the DAR to accept the installation.


Is this something relegated to restraint systems? Do DARs often require FAA approval of every fastener or connection?
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Mon Feb 25, 2019 4:08 pm

Re: FAA approved Carabiner? Shackle?

Zzz wrote:
whee wrote: if any are FAA approved which they need to be for the DAR to accept the installation.


Is this something relegated to restraint systems? Do DARs often require FAA approval of every fastener or connection?


The DAR I will be using said all hardware needs to be AN especially structural fasteners and seat belt fasteners. I don't know if this is a universal thing or not. Since I'm already pushing my luck on a couple hardware pieces (AN not available in the configuration I need) I want to make sure all the openly visible stuff is not going to draw closer scrutiny.
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Mon Feb 25, 2019 4:09 pm

Re: FAA approved Carabiner? Shackle?

Are your ends sewn onto the belts or threaded on?
My pax belts have clip-on fittings. Like this:
https://www.aircraftspruce.com/catalog/ ... rdware.php
Last edited by hotrod180 on Mon Feb 25, 2019 5:45 pm, edited 1 time in total.
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Mon Feb 25, 2019 4:33 pm

Re: FAA approved Carabiner? Shackle?

hotrod180 wrote:Are your ends sewn onto the belts or threaded on?
My pax belts have clip-on fittings.
Google aircraft spruce clip on seat belt fittings.


My ends are sewn on. Replacing my ends with clip-on end fittings from spruce is my backup plan but I’d prefer to avoid that option.
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Mon Feb 25, 2019 6:04 pm

Re: FAA approved Carabiner? Shackle?

The "double-lug stud fitting" locks to the track with a lock nut. ( 3/8-24 ) 1833 lb working load.
You would need to fabricate a metal extension to allow the belt "end fitting" to swivel, lay flat, or orient properly.

Bill
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Mon Feb 25, 2019 6:10 pm

Re: FAA approved Carabiner? Shackle?

-0-
Last edited by dogpilot on Thu Aug 06, 2020 1:07 am, edited 1 time in total.
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Mon Feb 25, 2019 6:43 pm

Re: FAA approved Carabiner? Shackle?

"Meatbombs" best thing all day!

Thanks I needed that.
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Mon Feb 25, 2019 6:46 pm

Re: FAA approved Carabiner? Shackle?

1. Some 5/32 or larger cable, two thimbles, and two nicopress fittings per belt end between belt and ring.
2. Two flat ski cable to landing gear bolt tabs with AN hardware through the two punched holes. One bolt though belt end hole the other through the ring clamping the tabs over both. Atlee Dodge product.
3. https://www.aircraftspruce.com/catalog/ ... /an115.php or https://www.univair.com/categories/hard ... ckles.html

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Mon Feb 25, 2019 7:37 pm

Re: FAA approved Carabiner? Shackle?

c180bill wrote:The "double-lug stud fitting" locks to the track with a lock nut. ( 3/8-24 ) 1833 lb working load.
You would need to fabricate a metal extension to allow the belt "end fitting" to swivel, lay flat, or orient properly.


I thought about those but wondered about the metal extension I'd have to build and how the DAR would like it. Also I wanted to remove teh seat and lap belts without tools but this solution would prevent that. Still a viable option.

dogpilot wrote:Seat belt attach points do have special regulations. If memory serves me correctly, the restrains must be able to restrain a standard FAA defined human at 10g acceleration. The reason for this, is above 10g, you essentially come apart internally in a rapid deceleration. So a restraint should be able to hold 180 lbs x 10g or 1,800. The seat track fittings on Ford type track, single point are 150 lb and double foot attachments are 250 lb. So these would be very inadequate for use as a restraint. That being said, skydivers frequently use two double point attachments to secure skydivers (meatbombs) seatbelts to the floor for jumping. They have STC's for that attachment system that go along with the benches used. They have very loose standards for nearly everything skydivery


I'm pretty sure it is 9Gs. The load rating of this L-track is limited by the fittings used. The stud fitting I planned to use is rated between 2000-4000lbs depending on pull angle.

PA1195 wrote:1. Some 5/32 or larger cable, two thimbles, and two nicopress fittings per belt end between belt and ring.
2. Two flat ski cable to landing gear bolt tabs with AN hardware through the two punched holes. One bolt though belt end hole the other through the ring clamping the tabs over both. Atlee Dodge product.
3. https://www.aircraftspruce.com/catalog/ ... /an115.php or https://www.univair.com/categories/hard ... ckles.html


Good ideas. I thought about swaging some cables but surely a carabiner would be better, at least that's what I would think. Option 3 might be the way to go. I need to measure to see if one of those shackles will fit.
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Mon Feb 25, 2019 8:26 pm

Re: FAA approved Carabiner? Shackle?

If the shackles don't work...

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Tue Feb 26, 2019 7:11 am

Re: FAA approved Carabiner? Shackle?

Yours is Experimental, why do you need a DAR’s approval?
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Tue Feb 26, 2019 7:50 am

Re: FAA approved Carabiner? Shackle?

Consider proof tested and tagged swaged assemblies from McMaster. I've seen a few installs using them. Economical, professional looking (with most terminations available), and the proof test/cert plates seemed to be convincing for their reps.
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Tue Feb 26, 2019 8:38 am

Re: FAA approved Carabiner? Shackle?

Whee,
Is there some way to have someone specialty weld a new d ring through the clip and the tie down or buy a I-track tie down, have someone cut and re-weld with seat belt clip on the D-ring that can then be certified?
Just a thought, I have no mechanical experience, don't know if allowable or not.
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Tue Feb 26, 2019 10:48 am

Re: FAA approved Carabiner? Shackle?

dogpilot wrote:Seat belt attach points do have special regulations. If memory serves me correctly, the restrains must be able to restrain a standard FAA defined human at 10g acceleration. The reason for this, is above 10g, you essentially come apart internally in a rapid deceleration. So a restraint should be able to hold 180 lbs x 10g or 1,800. The seat track fittings on Ford type track, single point are 150 lb and double foot attachments are 250 lb. So these would be very inadequate for use as a restraint. ...


FWIW I believe that the Atlee Dodge folding jumpseat installation uses these fittings per their STC.
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Tue Feb 26, 2019 11:57 am

Re: FAA approved Carabiner? Shackle?

http://www.ancra.com/aircraft/pdf/Ancra ... log403.pdf

A variety of studs and stuff that might work above, and designed for aircraft, seen above.

https://www.uscargocontrol.com/L-Track- ... ud-Fitting

The Harbor Freight version that you might actually be able to order without a hassle, seen above.

https://www.uscargocontrol.com/shop/Enc ... at-L-Track
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Tue Feb 26, 2019 12:07 pm

Re: FAA approved Carabiner? Shackle?

Whee- These are available if you search Amsafe on eBay or the like. I'm no DAR, but if it's good enough for a 737... (The difficulty is that the belts are sometimes configured a little short because they are intended to anchor in the seat frame and not on the cabin floor.)
-DP
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Tue Feb 26, 2019 1:49 pm

Re: FAA approved Carabiner? Shackle?

Bagarre wrote:Yours is Experimental, why do you need a DAR’s approval?

DAR issues the airworthiness certificate after inspecting the plane and logbooks to make sure it complies with EAB rules.

I appreciate the ideas guys. Sewing on new "clip" style ends is probably the better way to go and the belt assemblies DP posted from ebay are inexpensive enough that I can buy a few belts and salvage the ends from them.

I'm going to ask the DAR if he will accept steel carabiners certified for either climbing or industrial rigging. If he will not then I'll sew on new clip style ends.
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Tue Feb 26, 2019 3:14 pm

Re: FAA approved Carabiner? Shackle?

Whee,
In my past looking, it’s the sewing that pops up all the roadblocks. Seatbelt companies have too much at risk to help you with your project. Gear repair shops can do commercial-grade bar-tacking, but you won’t come away with a certified label. I assume that’s why Atlee and others provide a metal tri-glide buckle to customize seatbelt ends. Less elegant but more universal.
Good luck,
-DP
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Tue Feb 26, 2019 4:05 pm

Re: FAA approved Carabiner? Shackle?

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Last edited by dogpilot on Thu Aug 06, 2020 1:06 am, edited 1 time in total.
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