[Code of Federal Regulations] [Title 14, Volume 1] [Revised as of January 1, 2007] From the U.S. Government Printing Office via GPO Access [CITE: 14CFR23.231] [Page 204] TITLE 14--AERONAUTICS AND SPACE CHAPTER I--FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION PART 23_AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES--Table of Contents Subpart B_Flight Sec. 23.231 Longitudinal stability and control. (a) A landplane may have no uncontrollable tendency to nose over in any reasonably expected operating condition, including rebound during landing or takeoff. Wheel brakes must operate smoothly and may not induce any undue tendency to nose over. (b) A seaplane or amphibian may not have dangerous or uncontrollable porpoising characteristics at any normal operating speed on the water.