Apr 11, 2012, 7:18 AM
Post #1 of 16
Sewing seat belt
a friend of mine has a problem on his seat belt on his Cap 10, that needs some sewing work. Who has the ability to do this job ? Wich kind of thread would you use ? I don't know what the manufacturer recommend... Let me know if you know a better place to discuss this
Gentlemen, I have removed a few posts from this thread. Let me remind everyone that this is a topical forum and not BF/SC. Please reserve the bickering to PMs amongst yourselves if you wish to go tit for tat with one another. As always, post your responses here and in PM's the same way you would if you were speaking to that person face to face.
Thanks for your answers & PM. It's always intersting to know what the FAA says for a senior rigger, even if I'm in France ;)
I do not recall anything in my rigger training (Senior or Master) that permits me to make repairs to TSO'ed components of the aircraft/airframe. It only extends to me the authorization to do so to personnel parachutes.
While I suspect that a Master Rigger has more training on repair of webbing sewn components, I suspect that an FAA licensed aircraft mechanic would be required... in the USA.
As for France... maybe similar, maybe not... couldn't say.
The closest I've been asked to do was a (non-TSO'ed) replacement safety strap for a wing-walker stantion on a bi-plane... Replicated the original part, but no idea who had built that... Original worked for 30+ years. I plan to get them to replace them a little more frequently from now on...
Officially, FAA- licensed Senior and Master riggers can only work on TSO-C23? parachutes. They cannot legally repair seat-belts certified under TSO-C22. However, if an Aircraft Maintenance Engineer (A&P in the USA) is willing to sign on top of the repair, then a parachute rigger may re-sew seat-belts. This is similar to an A&P hiring a welder, then signing on top of the weld. Un-officially, if the parachute rigger sews neatly - and his work closely resembles the original TSOed stitch pattern, nothing will happen. There are even fewer restrictions on seat-belts for experimental (homebuilt or kit-built) or restricted (agricultural or warbird) aircraft.
The key point is understanding the design and loading of seat-belts. If you do not understand the loads imposed on seat-belts, then copy the original exactly (quoting Sandy Reid). ... Ooh! If you copy the original exactly, the FAA Inspector will probably not notice the difference!
Most seat belts are sewn with: Type 9 webbing, 3 inch wide, 9000 pounds, or Type 24 webbing, 2 inches wide, 5500 pounds. The wider webbing is popular with aerobatic pilots, who "push" a lot of negative Gs, that try to lift them out of their seats.
Two inch wide webbing is used for most other seat-belts in airplanes and cars.
Most seat-belts are sewn with FF thread (16 pounds), seat-belts can also be sewn with 5 cord (40 pounds). Since FF thread is only used in one percent of parachute container repairs, not all riggers stock FF thread.
5 cord is stronger than you need for seat-belts, but most Master Riggers already have 5 cord in their harness machines.
All these materials are available from major parachute supply houses like Para-Gear.
... As a result of an investigation on some maintenance organisations, EASA was made aware that safety belts and torso restraint systems manufactured by authorised (E)TSO approval holders, have been maintained or repaired by maintenance organisations without holding approved maintenance data. EC Regulation 145.A.45 requires that (E)TSO approved parts and appliances can be maintained or repaired only if approved maintenance data provided by the (E)TSO approval holder are used, pending the loss of validity of the (E)TSO approval and installation onto the aircraft. ...
Welcome to bureaucracy trumping sewing experience.
Remember that several airframe manufacturers (e.g. Cessna) say that seat-belts should be replaced every decade. (Try to picture the worst-case scenario: airplane parked outside, in the sun, hundreds of passengers tracking sand, oil, vomit, ???, etc. into the cabin).
As a Canadian Aircraft Maintenance Engineer explained it to me recently: "There are only two shops (one in Ontario and the other in Calgary) in Canada (Transport Canada) approved to re-web seat-belts. A man could make a fortune if he could get TC approval to set up a third shop."
Allan Silver has also grumbled long and loud about his frustration at applying for FAA approval to sew seat-belts for certified airplanes. Allan is a well respected FAA DPRE and has sewn seat-belts for hundreds of restricted (warbirds) and experimental (amateur-built) airplanes, but cannot get past te notion that the FAA only wants to certify a handful of (American) shops to sew seat-belts for certified airplanes?????