Airbus A321

A mostly aluminium airframe with composite parts where they save weight: control surfaces, fairings, the tail or the rotor blades. Aluminium fuselage and wings, composite tail. The design is held under 1 type certificate (A28NM, held by Airbus Sas). The FAA has issued 502 airworthiness directives (orders that owners must comply with) that name this model, most of them about airframe structure. Operators and repair shops have filed 39,560 failure reports with the FAA since 2001, 32,339 of them in the last ten years: about 345.5 a year for every 100 aircraft on the register; the system most often named is airframe structure. 294 approved modifications exist for it, the most by Delta Engineering Corporation.

Sources: the FAA's type certificate data sheets, airworthiness directives, supplemental type certificates, special conditions and special airworthiness information bulletins (Dynamic Regulatory System), and the FAA's service difficulty reports. A failure report is what an operator or repair station chose to file; the counts show reporting as much as reliability, and larger and commercial fleets report more. How the systems are grouped.