The National Air Transportation Association (NATA) still has concerns regarding new requirements for improved flammability characteristics of retrofitted thermal/acoustic insulation. This final rule significantly narrowed the scope of the requirement. However, in comments to the FAA, the association said hundreds of parts catalogs now contain part numbers that no longer comply with this rule. “Parts catalogs of many out-of-production models have not been addressed by this rule,” NATA said. “Operators risk enforcement action for operating aircraft with noncompliant replacement insulation.”