FAA Amends Appendix C in New Icing Regulations

 - August 9, 2007, 11:10 AM

The FAA yesterday released a final rule governing certification of transport-category (Part 25) airplanes for operation in icing conditions, effective October 9. In publishing the new rules, the FAA added new material to Part 25, Appendix C, the section that details the so-called icing envelope. The new Appendix C material, however, does not address the NTSB’s desire for the icing envelope to be expanded to include larger icing droplets. The new rules add specific requirements for airplane performance and handling qualities in icing conditions, whereas the existing rule specified only that airplanes be able to operate “safely in icing conditions if the applicant is seeking to certificate ice-protection features.” While the FAA chose not to address the Appendix C icing envelope, it did revise Appendix C to address the most critical ice accretions during various phases of flight. The agency isn’t finished with Appendix C and wrote, “We are considering future rulemaking action to address icing conditions beyond those covered by Appendix C of Part 25, and to provide flight crews with a means to positively determine when they are in icing conditions that exceed the limits for aircraft certification.”