Poly-Fiber patches

[Guest]

Re: Poly-Fiber patches

The stipulation is in the general section near the front of the manual. I certainly read it as applying to the whole process including repairs. The website is less emphatic but not inconsistent (assuming this plus the fact that the manual has been recently updated, represents Polyfiber's current position on the issue). From another perspective, I suspect if asked the question directly (can I use Stewart to repair my polyfiber covering) the answer would be no. But then the decision is ultimately for the governing body. Not sure about the FAA but Transport Canada views "manufacturers requirements" as the bottom line.

The part in red reminds of 2 things that may be relevant.

First is that I recall reading but cannot recall where that when I as an A&P/IA install an STC I am supposed to make sure it is compatible with previous modifications.

Second is that when I get a report from a DER creating approved data I can use it alone as approved data on a 337 (no field approval required) as long as it is complete approved data that considers other previous or current mods to the airplane (DER will confirm if it is complete).

So all I am saying is that history matters and must be considered by the mechanic especially if two things seem to conflict.

Dave R

[PA1195]

Re: Poly-Fiber patches

Layering STC's ?: See Appendix A, Item 9: https://www.faa.gov/documentLibrary/...AC_43-210A.pdf

The potential concerns caused by layering STC's: http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgSAIB.nsf/0/6b3f7124a27669c786257a290054d126/$FILE/CE-12-37.pdf

See page 12 for an easier read: https://www.faa.gov/news/safety_brie...MayJun2014.pdf

Time for a beer.

Gary

[Hank Jarrett]

Re: Poly-Fiber patches

Scott,

I think you have pretty well covered it, but maybe I could add just two small items:

First, the FAA would be hard pressed to violate you for doing a Stewart System patch on Poly fiber, since they have approved both STC's as written. They have simply written a built-in conflict into the regs. That's their problem, not yours'.

On the other hand, Poly Fiber would probably declare themselves off the liability hook because you violated their instructions. And I bet that would successfully cloud the issue on any future liability claim against them.

Second, about the supplied air breathing system. I'm 100% with you there. I'm an emphysema case who never smoked a day in my life. Exposure to solvents probably isn't the sole cause of my health problem, but it probably was a significant contributor. And I have been (I thought) fairly careful all my life.

My biggest problem with the HobbyAir is, like you, the hose. When spray painting, I wind up holding both hoses (spray gun air and breathing air) in one hand to prevent the hoses from touching my work. That leaves the other hand free to hold the spray gun. But, what about when applying tapes, & doilies ? Then I need both hands to lay down the fabric. My latest solution has been to make a new air supply hose that goes from the belt clip to the mask. The new hose attaches to the belt clip (just like the old hose), but goes around to my back where I have a Y-fitting that splits into two 18" flex hoses which go symmetrically over my shoulders and join back together at the mask inlet. Sort of like an old style Aqua Lung where the regulator was at the top of the tank. The new Y-hose arrangement is made from three 18" lengths of CPAP flex hose and a couple of modified PVC sprinkler fittings. The quick disconnect at the belt clip is taken from the original hose and the new Y-fitting at the mask just pushes onto the stub of the mask. No permanent modifications to HobbyAir system. The CPAP hoses have pre-molded ends, so they are just push-on connections. The entire project cost about $15 in materials and 2 or 3 hours on the lathe to modify the ends of the PVC fittings. Now, my air supply hoses rest comfortably on my back and do not sag to touch my work surface.

Dick

Dick,
Your mods to the breathing system sound great. Any way you could post a series of photos of the rig?

Hank

[Guest]

Re: Poly-Fiber patches

Layering STC's ?: See Appendix A, Item 9: https://www.faa.gov/documentLibrary/...AC_43-210A.pdf

The potential concerns caused by layering STC's: http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgSAIB.nsf/0/6b3f7124a27669c786257a290054d126/$FILE/CE-12-37.pdf

See page 12 for an easier read: https://www.faa.gov/news/safety_brie...MayJun2014.pdf

Time for a beer.

Gary

Thanks Gary,

Good find(s).

Dave R.

[PA1195]

Re: Poly-Fiber patches

As I mentioned I have had some inspection rings installed with Stewarts over Poly-Tone. So far they are holding - two years. After cleaning the Poly-Tone per their recommendations it was easy to glue the acetate inspection ring on with a brush and place fabric over ring. Work glue into fabric weave. Mechanic wiped them with a quality blue shop paper towel to remove any excess of glue or silver overrun before they dried. Let dry then their silver and color. Then cut out hole for 4-point rings and installed them. I left mine silver in case they separated which none have. I'd do it again plus any small area patching through color.

Multiple or layered STCs are often common and expected on older planes in Alaska. There's usually a disclaimer and caution with each that emphasizes the need to determine compatibility. If the installer doesn't fly then physically it's their call of course. I've been tasked on my planes to go fly and confirm the flight envelope as best I can within reasonable limits. Speeds, control response, overall behavior, and to note any changes adverse or otherwise.

I had a Citabria that had a modified wing. First stock, then Crosswind's STOL kit (cuff/stall fence/end extensions on flaps/sealed controls and flap gaps). No problems and did well. Then I had Madras droop tips installed on spar slices and extensions. They use a Piper USA-35B airfoil form for the droop add-on so that had to be converted from the NACA 4412 of the Champ at the tip. It flew ok but in turbulence the tips flexed the wood spar wings and slowed aileron roll. The flex was either from the added weight at the end of the wing or more lift.I left them on but would not do that mod again.

Compatible? Not for me but it probably was still airworthy with the two STCs.

Gary