The International Cessna^® 170 Association

I'm looking for advice from folks that might have done similar.

I'd like to use some fabrics that don't come with burn certs.

What is the burden of proof for flame resistant materials used in cabin upholstery?
Do I need to send it off to a burn lab or can I perform the tests myself and document the findings?

Is it permissible to apply flame retardant treatments to the fabric in order to make them pass?
Like this?: https://www.amazon.com/No-Burn-1005-Fab ... _bxgy_60_2

David,
Great question, especially for those trying to get their interiors back as close to original as possible. The answer is not so simple as Greg Amy writes here. Unlike his aircraft though, ours was certified under CAR 3, back when aircraft were covered in cotton fabric shrunk with highly flammable nitrate dope and when smoking was ubiquitous. Pilot's were braver back then! The C-170 must meet the requirement of CAR 3.388, not FAR 23.
CAR 3.48(d) defines "flash resistant:

Any A&P may conduct the burn tests specified in CAR 3 and make a logbook entry. I recommend a small sample of the fabric be stapled into the logbook along with the entry. (I once observed the CAR test on seat coverings and, relying upon questionable memory, it involved a very simple horizontal-burn test where the fabric self-extinguished when the flame source was removed. The vertical test required that it burn less than 2" of length within 1 minute, a piece of fabric 1" wide. )

At last note, Skandia, Inc. 800-945-7135 , will conduct tests on fabric for $40 and certify the result also. Contact them directly for addt'l info on their services.

Hope that helps.