SAIB Focus on Icing and Stall Warnings
January 27, 2011 — Owners of Part 23 airplanes certificated before 2000 should know the potential hazards associated with stall warning characteristics in icing conditions, says a Special Airworthiness Information Bulletin (SAIB) issued this week by the FAA. After studying icing-related, non-fatal incidents over the past 25 years, the FAA found evidence of stall events during flight in icing conditions in which either the pilot or passenger explicitly stated the stall warning system did not activate.
In new Part 23 airplane designs certificated since 2000, current icing regulations apply in that the stall warning system is designed and tested with critical ice accretions along the entire span of the wing. In many new designs, this results in the stall warning speed biased higher in icing conditions.
rior to 2000, a clear and unambiguous buffet was accepted for stall warning in icing conditions, even if the airplane was equipped with a stall warning system and a heated stall warning sensor. Prior to 1973, there were no requirements to test Part 23 airplanes in icing conditions.To read the entire SAIB, including FAA recommendations for the older airplanes, click here.