This advisory circular (AC) provides information about the requirements of Title 14, Code of Federal Regulations (14 CFR) part 21 , Certification Procedures for Products, Articles, and Parts for quality systems for the manufacture of composite structures. These structures involve fiber-reinforced materials; for example. Carbon (graphite), boron, aramid (Kevlar) and glass reinforced polymeric materials. This AC also provides information about essential features of quality systems for composites as mentioned in AC 20-107, Composite Aircraft Structure. This AC provides information for both an applicant for, and a holder of, a production approval, and refers to both as a production approval holder (PAH). This AC is not mandatory and does not constitute a regulation. This AC describes an acceptable means, but not the only means, to comply with these requirements. However, if you use the means described in the AC, you must follow it in all important respects.