[1][2] Equivalent test requirements are provided in the Certification Specifications for Engines (CS-E), published by the European Aviation Safety Agency (EASA).

One of the most challenging component design and certification requirements for commercial jet engines is to mitigate the effects of a "blade-out" rotor failure event, which can result in catastrophic loss of aircraft and/or passengers.

Testing rotor dynamics and blade-out conditions to ensure safe operation is extremely expensive, time consuming and labor intensive.

The study concluded that redundant armor could be added to the airframe in addition to engine-mounted containment, but at a substantial weight penalty of 2,500 or 3,000 pounds (1,100 or 1,400 kg) for 3 or 4 engine aircraft, respectively.

"[12] A series of superseding advisory circulars (ACs) were issued in 1965,[13] 1968,[14] and 1970[15] to provide guidance to demonstrate compliance to the requirements of the Airworthiness Standards.

"[15] Amendment 10 to the Airworthiness Standards was published by the Federal Aviation Administration on February 23, 1984, which modified the durability requirement of 33.19 by adding that "energy levels and trajectories of fragments resulting from rotor blade failure that lie outside the compressor and turbine rotor cases must be defined" and by moving some requirements for blade off testing from the advisory circulars to a new regulation (14 CFR 33.94).