Story ID: 
Draft AC Offers OEMs Guidance on Icing
By: Chad Trautvetter
Caption: The FAA’s Draft Advisory Circular 20-147A released last month provides  new guidance to aircraft manufacturers on compliance with regulations  covering eng
Word Count: 150
The FAA’s Draft Advisory Circular 20-147A released last month provides  new guidance to aircraft manufacturers on compliance with regulations  covering engine ­induction system icing and engine installation ice  requirements. Comments on the draft AC are due by November 1. One of the  key changes in the draft AC is mixed phase or ice ­crystal icing  conditions, which “has caused more than 100 turbine engine power  losses,” according to the FAA. These conditions “occur when supercooled  liquid water droplets and ice particles coexist in a cloud, often around  the outskirts of a deep convective cloud formation.” This is the first  time the FAA has introduced compliance methodologies for these  conditions and is likely a response to instances of power rollbacks that  have caused engine flameouts in at least three Beechjets. The FAA is also recommending that  ice-detection systems be evaluated for TAT probe ­malfunctions during  icing events. (See article on page 1.)