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riggerrob

Aircraft seat belts (was - airplane flips on landing)

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billvon,

You and I are going to have to agree to disagree on this subject. Hooker's skydiver specific seat-belts have been tested by the FAA.
Back in 1997, I helped with a PIA/FAA simulation that involved Hooker belts and simulated skydivers on the FAA's crash test sled in Oklahoma City. After viewing video of the third simulated crash, we "got it!" Hooker's belts prevent you from flailing around the cabin.

In a peculiarity, Hooker's skydiver specific seat-belts are manufactured under FAA TSO C22 (seat-belts), but are not STCed to install in popular jump planes???????
I am not sure if the lack of STC is a Canadian or American problem.

I have tried the alternative ... and it only took 6 years to find a surgeon who knew how to fix my "interesting" knee injury.

More recently, I have been seen snapping tandem student side straps to cargo rings. One major tandem manufacturer said that they would not forbid the practice nor would they condone it. Their objection was more legal than technical. Using tandem side straps as restraints blurs the border between FAA TSO C22 (seat belts) and C23 (parachutes). Lawyers could argue that border for a decade. The other problem is the high cost of testing.

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riggerrob

billvon,

You and I are going to have to agree to disagree on this subject. Hooker's skydiver specific seat-belts have been tested by the FAA.
Back in 1997, I helped with a PIA/FAA simulation that involved Hooker belts and simulated skydivers on the FAA's crash test sled in Oklahoma City. After viewing video of the third simulated crash, we "got it!" Hooker's belts prevent you from flailing around the cabin.

In a peculiarity, Hooker's skydiver specific seat-belts are manufactured under FAA TSO C22 (seat-belts), but are not STCed to install in popular jump planes???????
I am not sure if the lack of STC is a Canadian or American problem.

I have tried the alternative ... and it only took 6 years to find a surgeon who knew how to fix my "interesting" knee injury.

More recently, I have been seen snapping tandem student side straps to cargo rings. One major tandem manufacturer said that they would not forbid the practice nor would they condone it. Their objection was more legal than technical. Using tandem side straps as restraints blurs the border between FAA TSO C22 (seat belts) and C23 (parachutes). Lawyers could argue that border for a decade. The other problem is the high cost of testing.



Hookers belt systems don't have to be STC'ed, they can be installed and field approved on a 337 in the USA.

As spelled out in the new AC105-2E, The FAA RECOMMENDS that those seated on straddle benches, or the floor use TWO (2) of those Hooker single strap style skydiver belts attached at a 45 degree angle to the seat track below, one on each side passed through the hip ring area of the skydivers main harness.

Also, each occupant MUST wear a seat belt. An instructor wearing a belt and then using the tandem laterals to the student, thus sharing a single belt, is NOT permitted.

Seat belts are REQUIRED to be used BEFORE aircraft movement on the ground, and through take off and Landing. This is not open for discussion or interpretation.

See AC105-2E
http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_105-2E.pdf

And FAR 91.107

Wear your seat belts. Simple. Keeps you alive, and the pilot from getting violated by the FAA. Use them properly, use them all the time, and feel damn lucky the pilot doesn't do a flight attendant style seat belt use briefing like he/she is technically required to do before EVERY flight.
Airline Transport Pilot, Multi-Engine Land, DHC-8
Commercial Multi-Engine Sea, Single Engine Land
Private Glider

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Actually you wouldn't even need to do a 337. A 337 for seating is more for the configuration change (removing original seats, adding jump seats/straddle benches, more passengers than type certified, etc..)

Being that the seatbelts are manufactured under the guidelines of the TSO means that swapping the standard lap type belts for the Hookers would be a MINOR deviation.

It's kind of like installing a PMA part, (for those who don't know PMA means Parts Manufacturing Authorization and represents most aftermarket direct replacement parts). No approval is needed since the products are manufactured using, at least, the minimum standards as set by the FAA. Same as a TSO.
Disclaimer: you can't installed a FAA/PMA part designed for a Piper on to a Cessna without approval.
In Canada I believe they're called PDMs, Parts Designated Manufactures. Correct me if I'm wrong Rob.

Now if you had your rigger wip up a couple seat belts using some lift webbing, then you'd be looking at an STC. At least in the States.

Edited to add for clarification: TSO stands for Technical Standard Order and is used to set the minimum standard that a part needs to be manufactured to. With seatbelts its mainly material and strength rating. And TSOs are used for Non Aircraft Type Specifc items, seatbelts, instruments, radios, etc.. Those items that could be used in more than one aircraft type. And in order to install these types of items on a Type Certified aircraft they must be TSOd.

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Hi totter,

Quote

(for those who don't know PMA means Parts Manufacturing Authorization and represents most aftermarket direct replacement parts). No approval is needed since the products are manufactured using, at least, the minimum standards as set by the FAA.



A few years ago there were some changes to Part 21 regarding Quality Programs and some of the changes were to include anyone who is a Production Approval Holder, to include PMA folks.

So, anyone mfr'ing under a PMA now has to have a Quality Program approved by the FAA. Which for a lot of these small guys is/was a huge mountain to climb.


And I know you were talking about certification approval.

Jerry Baumchen

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>You and I are going to have to agree to disagree on this subject. Hooker's
>skydiver specific seat-belts have been tested by the FAA.

I totally agree that we should all be wearing seatbelts, and the tighter, the better.

But ask Cessna if their C208 is certified for seatbelt usage when a single seatbelt is attached to a cargo tie-down. Ask Bill Booth if his harnesses are certified for use as an aircraft restraint.

We aren't using certified systems designed to protect us. We are getting around the rules by taking advantage of a loophole in part 105 that allows parachutists to sit on the floor rather than in approved seats using approved seatbelts. Fortunately, every FSDO I have ever talked to has considered the use of seatbelts to be a good thing, and thus supported their use even with the questionable certification status of such devices.

This leads to a very wide variation in systems. Some are actual approved seats with approved seatbelts. Great! Some are lap belts using approved seatbelts. This is pretty close to the approved design and would likely provide significant protection in a crash. An example of this is the Perris otter. Bench seats with seatbelts. But will that bench seat - fairly thin welded steel tubing with plywood on top - survive a crash, or will it collapse and dump everyone forward into the person across from them? Hard to say. I do know they've never been tested that way. But still far better than nothing (IMO.)

Some systems are a single belt, attached to a single point, allowing people to sit on the floor and wrap the belt around a legstrap or chest strap or MLW. None of those harness points are designed for that load, although the leg strap is designed for very similar loads and would likely survive. And you're going to get slung about in a circle whose center is the attachment point. Still better than nothing - although in some cases barely better than nothing. I remember one C206 with a seatbelt for the person in jumpmaster position that was long enough so that his body could reach every part of the cabin. Convenient but not all that useful in a crash. I imagine it might prevent him from being ejected.

There have been a few tests done where specific sorts of seatbelts were tested. I recall seeing one test where carabiners were used to attach to both laterals (or both hip rings) that looked promising, but since then I have never seen a carabiner-based system, although they'd be far more reliable than the webbing-to-webbing system most places have. We really need to do some more specific testing so that we can evaluate how harnesses work as seatbelts, what problems they have and how best to use them.

Until we do that, we'll be doing the best we can - which might include Hooker belts, or snapping tandems to cargo rings, or fabricating seats with lap belts, or other designs with varying degrees of thought put into them. And they are absolutely better than nothing. But they're not approved either, and we're not using systems that have really been tested to either protect ourselves from crashes, or protect others from our bodies.

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billvon

>You and I are going to have to agree to disagree on this subject. Hooker's
>skydiver specific seat-belts have been tested by the FAA.

I totally agree that we should all be wearing seatbelts, and the tighter, the better.

But ask Cessna if their C208 is certified for seatbelt usage when a single seatbelt is attached to a cargo tie-down. Ask Bill Booth if his harnesses are certified for use as an aircraft restraint.

We aren't using certified systems designed to protect us. We are getting around the rules by taking advantage of a loophole in part 105 that allows parachutists to sit on the floor rather than in approved seats using approved seatbelts. Fortunately, every FSDO I have ever talked to has considered the use of seatbelts to be a good thing, and thus supported their use even with the questionable certification status of such devices.

This leads to a very wide variation in systems. Some are actual approved seats with approved seatbelts. Great! Some are lap belts using approved seatbelts. This is pretty close to the approved design and would likely provide significant protection in a crash. An example of this is the Perris otter. Bench seats with seatbelts. But will that bench seat - fairly thin welded steel tubing with plywood on top - survive a crash, or will it collapse and dump everyone forward into the person across from them? Hard to say. I do know they've never been tested that way. But still far better than nothing (IMO.)

Some systems are a single belt, attached to a single point, allowing people to sit on the floor and wrap the belt around a legstrap or chest strap or MLW. None of those harness points are designed for that load, although the leg strap is designed for very similar loads and would likely survive. And you're going to get slung about in a circle whose center is the attachment point. Still better than nothing - although in some cases barely better than nothing. I remember one C206 with a seatbelt for the person in jumpmaster position that was long enough so that his body could reach every part of the cabin. Convenient but not all that useful in a crash. I imagine it might prevent him from being ejected.

There have been a few tests done where specific sorts of seatbelts were tested. I recall seeing one test where carabiners were used to attach to both laterals (or both hip rings) that looked promising, but since then I have never seen a carabiner-based system, although they'd be far more reliable than the webbing-to-webbing system most places have. We really need to do some more specific testing so that we can evaluate how harnesses work as seatbelts, what problems they have and how best to use them.

Until we do that, we'll be doing the best we can - which might include Hooker belts, or snapping tandems to cargo rings, or fabricating seats with lap belts, or other designs with varying degrees of thought put into them. And they are absolutely better than nothing. But they're not approved either, and we're not using systems that have really been tested to either protect ourselves from crashes, or protect others from our bodies.




Again, read the new Advisory Circular for FAR Part 105, AC105-2E. They go into great detail to explain how they recommend all straddle and floor seated occupants in jump aircraft should be restrained. 45 degree angle to double anchor cargo rail attach points to single strap Hooker style skydiver restraints on each side of each occupant. That is TWO (2) single strap seat belts PER OCCUPANT, passed through the hip area of the parachute harness assembly.

EACH aircraft, when converted to a jump plane, MUST have those modifications approved by the FAA on a field approval (Form 337) for jumping, and in those modifications, you must show supporting data, from a previously approved 337, or through supporting engineering to back up your modification request. In those 337's you will see the data and drawings for floater bars, door removal, jump door installations, seating surfaces, occupant restraint systems (those will spell out HOW the jumpers are restrained, with what kind of restraint system and what manufacturer of those systems, and any deviation from that is against the 337 and is a violation) instructions for continued airworthiness (inspection criteria and maintenance intervals) and a pilot operating handbook supplement that spells out changes to aircraft redline speeds, stall speeds etc, as well as weight and balance changes, dynamic weight and balance during jump run, and sample loading diagrams.

There is WAY more to making a certified aircraft a jump plane then ripping out the interior, slapping some belts on the floor and calling it good. Those belts, and all other modifications once approved are not permitted to be modified, moved, changed or altered in any way without FAA approval. Even something simple as changing from one seat belt style to another requires approval. And if your 337 lists a manufacturer for the seat belts, you are not permitted to change to a different manufacturer. Most 337's list generic parts for those so it is usually not a big deal, but it has the potential to be a problem.

Another example is the roll up lexan door. If you used 3/16 inch thick Lexan panels in the original approval, you are not permitted to switch to 1/8 inch or 1/4 inch thick or even to go to Plexiglass being as they possess different weights, strengths, and breaking characteristics. When it comes to the FAA, there is very little room for change unless approved.

Even moving the seat belts in the tracks 3 inches either direction from the position spelled out in the approval can trigger a violation.

So, make sure your belts are in good condition, tags are legible, and in the proper location and use the damn things.

Everybody get their own belts. That is not open for discussion or negotiation. A tandem master wearing a belt and clipping the lateral of the student to himself is not acceptable. And one very large southern DZ apparently has been telling their TI's that this is acceptable. It is NOT.

Sharing of seat belts is NOT allowed.

As for Cessna saying if the belts are approved to be used attached to the cargo track, they do not have a say in the matter, just as Mr Booth doesn't either. Those products are required to be manufactured to a certain standard with the intent that they will be used to attach seats, and restrain cargo and other types of restraints. Seats clip into the C Track, and belts are attached to the seat, therefore it is implied the tracks can handle the directional loads of the seat belts themselves. As those harnesses are intended to be used for skydiving, and certified for such, they are assumed to be able to handle the loads as it pertains to restraining the jumper to the aircraft, but also spells out that if the harness system is subjected to the stresses of a crash, it will be inspected for damage and future serviceability by a certified rigger.

This is an excerpt from FAA AC 105-2E in regards to the harnesses taking seat belt loads.

d. Restraint Belts or Tethers. Past experience and testing have shown the validity of attaching a restraint belt(s) or tether(s) to the parachute harness as part of the overall integrated restraint system. However, most manufactuers have not tested their parachute harness configurations to see if they can accept the load vectors that would be experienced during the actual use of this type of restraint configuration. Because of this, any parachute harness that has been subjected to actual use as part of an integrated restraint system must be removed from service and inspected by the manufacturer or a parachute rigger designated by the manufacturer to determine the continued airworthiness of the parachute harness. If the inspection shows that the harness is Airworthy, it may be returned to service.
Airline Transport Pilot, Multi-Engine Land, DHC-8
Commercial Multi-Engine Sea, Single Engine Land
Private Glider

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Does anyone know of a TSO'd or STC'd Carabiner setup for a seatbelt? I remember seeing Jay Stokes was using a set up like this for his Most Jumps record jumps. (Parachutist November 2014 on Page 51)
Yesterday is history
And tomorrow is a mystery

Parachutemanuals.com

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Quote

occupant restraint systems (those will spell out HOW the jumpers are restrained, with what kind of restraint system and what manufacturer of those systems, and any deviation from that is against the 337 and is a violation) instructions for continued airworthiness



Uh, No.

You do not need mention who makes the belt, just that they are TSOd and how/where they are attached.
The Field Approval is not for the seat belt, unless you are using one made by your rigger. The Field Approval is for the configuration change from the TCDS.

Quote

Those belts, and all other modifications once approved are not permitted to be modified, moved, changed or altered in any way without FAA approval. Even something simple as changing from one seat belt style to another requires approval. And if your 337 lists a manufacturer for the seat belts, you are not permitted to change to a different manufacturer.



Uh, No.

Had a Caravan where the original approval was for the co-pilot's seat to be turned around and be used as the most forward seat. After use it was decided that not having the seat would be better and sliding the straddle bench all the way forward.
This was deemed a minor deviation from the original approval and just required a log book entry and a W/B form change.

Quote

Another example is the roll up lexan door. If you used 3/16 inch thick Lexan panels in the original approval, you are not permitted to switch to 1/8 inch or 1/4 inch thick or even to go to Plexiglass being as they possess different weights, strengths, and breaking characteristics.



Uh, Yes.

Your analogy is comparable to using oranges instead of apples and calling it a Pumpkin Pie.
Why do I say this, its because seat belts are TSOd. They are manufactured to the minimum standards as set forth by the FAA.
The lexan you buy for the jump door at Home Depot/Lowe's is not manufactured to any aviation industry standard. It's not certified in any way so it needs approval to use.

Changing from one seat belt manufacture to another is a minor deviation from the original field approval. Why, because all aviation seat belts are manufactured to the FAA minimum standards (TSO) and switching from one manufacture to another does not make a appreciable change to the original approval.
Changing the style, minor

Minor deviations are allowed and only require a log book entry.

The one point where I would agree with you is if you change the manor in which the belt is attached to the airframe.
Example: You are currently flying a Cessna that uses the original floor attach point where an AN bolt is used to hold the belt on. You want to change this to a Douglas type seat/cargo track so that you can use a quick release cargo ring.
This would require a revision to the original 337 ICA.

And here is the section from AC43-210.
Quote

508. When should an ICA be revised?
An ICA should be revised when experience with the product show the way that the product is maintained or inspected needs to be changed.

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Hi totter,

Quote

The lexan you buy



I would to offer some additional advise; from some who uses 'Lexan' in a cerificated product(s).

Never box yourself into a corner by saying, 'Use Lexan . . . '

Try to say, 'Use a 1/8th poly-carbonate, such as Lexan or similar, for . . .'

Lexan is a trade name. If you list it and your supplier changes manufacturers ( his suppliers ) who cannot use the trade name Lexan, you just might finding yourself unable to use some other poly-carbonate.

Just my $0.02 on this,

Jerry Baumchen

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Agreed Jerry.

I've always just referred to it as Lexan, as a general term. Never thought of it as a trade name.
And as a side note, don't use the stuff they sell at Home Depot either.
It gets brittle when cold and will shatter if the door is slammed.
Ask me how I know!

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You are all saying exactly what I am saying, just in different words.

Make sure you are in compliance with your paperwork.

I have done a fair few 337's and depending on your FSDO, they *MAY* require more data than you are used to providing, and that *MAY* make your paperwork more restrictive.

I wouldn't have said it, if I have not experienced it.

Lexan and Plexiglass have VERY different characteristics, and if Plexiglass (Cast cell acrylic) is used in a jump door in leiu of Lexan (poly-carbonate) you will have very different performances of the product.

And yes, some FSDO inspectors can be a-holes about it. And some want more detail to the 337 than others.

And a "minor deviation" requires a log book entry. IF that change is made without the appropriate log book entry, would you or would you not be in violation?

You would be. Just like putting the regular doors back on a twin otter for a ferry flight. A log entry and changes to the W&B is required before flight. As is installing the copilots seat in the Cessna/King Air etc for pilot training....

Nothing can be done without appropriate changes to the paperwork.

Too many years seeing jumpers grabbing stuff and moving it around to suit their personal desires...

Pilots need to protect themselves from violation, as do the mechanics...
Airline Transport Pilot, Multi-Engine Land, DHC-8
Commercial Multi-Engine Sea, Single Engine Land
Private Glider

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totter

Agreed Jerry.

I've always just referred to it as Lexan, as a general term. Never thought of it as a trade name.
And as a side note, don't use the stuff they sell at Home Depot either.
It gets brittle when cold and will shatter if the door is slammed.
Ask me how I know!




If your door shatters when cold, you either used Plexiglass or another type of cast or extruded acrylic and NOT a poly-carbonate like name brand Lexan. For what it is worth, you CAN use SOME name branded Lexan and Plexiglass products that have the Mil-Spec listed on them. Lexan Blue and Red are two examples, and can be ordered through Lowes, but you will pay a premium. All Plexiglass branded Acrylic is MilSpec, but is very expensive. You generally use Plexiglass for molding windshields and fixed aircraft windows. If you want flexibility in all temperatures you need to use a Poly-Carbonate like Lexan. It has better flexibility and cold weather performance. The downside to the poly-carbonates is a much lower scratch resistance due to it's softer structural make up. The upside is its much better machine-ability and higher tolerance for ham handedness when being worked. Acrylics are optically superior, but require edge polishing via flame or increasingly finer grades of abrasives, are much harder to drill, are much stiffer, harder and can be polished.

So yes, it does matter. That is why the last set of jump doors I made were required to have the manufacturer and part number of the poly-carbonate to be spelled out in the 337 by the approving FSDO.

What it boils down to is every FSDO is different, and every FSDO inspector is different too.


FWIW
Milspec Lexan is Part numbers 9604 and F2104 and meets FAR 28.853 A and B.
Plexiglass II-UVA and P55 are also Mil Spec as are most of the Acrylite and Polycast stuff.
Airline Transport Pilot, Multi-Engine Land, DHC-8
Commercial Multi-Engine Sea, Single Engine Land
Private Glider

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twatterpilot

There isn't one to my knowledge.

He was probably not in compliance, and it was probably not wise to publish pictures of it. If you find out more details, keep us posted.



I actually asked about it here http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=4669047#4669047

If you watch some of the videos, it looks like the safety just lays on him as the plane is starting to roll. I remember seeing some sort of inside video that I cannot find anymore that looked like they were clipping a carabiner on his harness as his seatbelt.

ETA: found the video http://indy.st/1o8Bl5T chest strap is unconnected, I don't know what kind of webbing that 'seatbelt' had on it but it looked pretty flimsy and very loose (lots of slack) and the aircraft is moving before he has the carabiner attached.
"I may be a dirty pirate hooker...but I'm not about to go stand on the corner." iluvtofly
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