Proposed rule overhauls airworthiness standards for small general aviation airplanes with max seating capacity of 19 passengers or less and max takeoff weight of 19,000 lb or less. Notice of Proposed Rulemaking restructures existing certification standards and replaces current prescriptive design requirements in Part 23 with performance-based standards that maintain same level of safety. It adds new standards to address general aviation loss of control accidents and in-flight icing conditions.