14 CFR 21, Subpart P - Special Federal Aviation Regulations

On December 4, 2012, the FAA published a final rule; request for comments (77 FR 71691) to make the existing regulation consistent with the FAA's intent and with the certification practice both before and after the adoption of the existing rule. The 2012 final rule clarifies what an applicant must show regarding a “changed product” to comply with applicable standards and became effective on February 4, 2013. We sought public comment on that final rule even though it is only clarifying in nature. This action responds to the public comments the FAA received.

This rule amends the regulations governing noise certification standards for issuing type and airworthiness certificates for a new civil, hybrid airplane-rotorcraft known as the tiltrotor. This noise standard establishes new noise limits and procedures as the basis to ensure consistent aviation noise reduction technology is incorporated in tiltrotors for environmental protection. It provides uniform noise certification standards for tiltrotors certificated in the United States and harmonizes the U.S. regulations with the standards of the International Civil Aviation Organization's (ICAO) Annex 16.