Smart Owner: Aftermarket Cabin Fabrics

What timing. Just as we begin our Smart Aviator field reporting on aircraft interior refurbishment, a reader reached out asking about the legalities of installing materials not having FAA approval (or at least material that doesn’t have the right paperwork to support an acceptable logbook entry). Buying a used certified airplane with aftermarket interior work? It’s worth a close look at the logs—there are plenty of planes with automotive and marine interiors (many are beautiful show winners) with no paperwork to back up the installation. Someone can flag that as unairworthy. The technicality is about the burn, mostly.

Lighting up in There?

Our first stop was FAA’s AC 43.13-1B, Chapter 9, Section 4, which has guidance for cabin interiors. Specifically, the AC applies to CAR-3 aircraft flown under Part 91—with specific, believe it or not, advice about occupants smoking something in the cabin. The AC says that if smoking is prohibited in the cabin (there must be a placard), the interior materials used shall be flash-resistant, and that references CAR-3.388. This could be fire-retardant foam, treatment on the fabric, or layered Kevlar as a blocker. For compartments in the aircraft where smoking is permitted, the cabin walls and headliner, upholstery, flooring, and furnishings shall be flame-resistant. Ensure there are enough available ashtrays for the smokers. 

Unapproved fabrics still can be independently burn-tested by facilities approved to do that kind of testing, but the costs and effort might not make sense over buying material that’s already been tested and approved in the first place. A principal FAA inspector pointed out that while plenty of aircraft fall under the CAR-3 standard, it’s more stringent Part 23 regulations that rule for newer models—where interior standards are more comprehensive in scope and also more rigorous in requirements. Hit the FAA data and type certificate data sheet to be sure of your model.

It’s Also About Paperwork

Digging deeper into the AC, if interior fabric is bought in bulk to refurbish the interior, seats, and ceiling liners for a CAR-3 aircraft used for Part 91, a manufacturer’s statement declaring that the material meets ASTM (American Society for Testing and Materials) standards should be acceptable.

Our read is that since the FAA would accept and recognize a national standard, the mechanic signing off the work would simply reference the manufacturer’s statement and the national standard that the actual material meets in the maintenance records. If this doesn’t exist, we wouldn’t install it.

But what happens if a modded airplane sporting an obvious aftermarket custom interior ends up at a shop for an annual inspection? We’d think any sharp IA would look for the supporting paperwork. If there is no mention of a manufacturer’s statement that the fabric is flash or flame resistant, he would assume the fabric or components are unapproved parts.

If it’s an aftermarket interior part with PMA or TSO, the sign-off paperwork would include an FAA Form 337 with the STC number in block 8 of the form. For Part 23 aircraft interiors, the materials used must meet requirements in section 23.853, and the burn test requirements called out in part 23, appendix F. Otherwise, a burn test would have to be done on samples of the material and fabrics by an approved and rated FAA Repair Station. If it passes, the repair station can sign it off accordingly. If the stuff has STC or TSO approval, it’s no different than signing off any other major modification.

DIY Upgrades

There are too many aftermarket mail-order custom interior companies to list in one sitting, and we’ll look at the market, typical investment, and the installation effort that’s required in our upcoming interior refurbishment series. We’ll start with carpet upgrades in the first installment.

But the takeaway for our reader question about the legalities of DIY seat and sidewall fabric projects is to simply choose components that meet the regulatory requirements for burn testing. Better yet—buy kits that have PMA or an STC. It’s tempting to skate the regs, but you don’t want to get stuck with an installation that a mechanic deems unairworthy, and you certainly don’t want to be in a fiery wreck seated in a cabin decked out with materials that easily ignite.