Although the requirements are slightly different between 25.853 and 23.853, would the same case apply to a Part 23 normal certified airplane required to comply with 23.853(a)?
There is no data available. The interior was customized many years ago and there are no details about finishing in the paperwork. “Worst” scenario would be to build a surrogate panel as AC 20-178… and we are trying to avoid it.
Is it necessary to carry out a new flammability test by 25.853(a) / Appendix F Part I(a)(1)(i) on the material sample from a cabinet and internal partition door which has been re-coated with a new polyurethane finishing that meets 25.853? The old lacquer/urethan coat would be sanded or scraped...