CS 22.629 Flutter

• ED Decision 2003/13/RM found in: CS-22 Amdt 2 - Sailplanes and Powered Sailplanes (Feb 2022)

CS 22.629 Flutter ED Decision 2003/13/RM (a) The sailplane must be free from flutter, aerofoil divergence, and control reversal in each configuration and at each appropriate speed up to at least VD. Sufficient damping must be available at any appropriate speed so that aeroelastic vibration dies away rapidly. (b) Compliance with sub-paragraph (a) must be shown by: (1) a ground vibration test which includes an analysis and an evaluation of the established vibration modes and frequencies for the purpose of recognising combinations critical for flutter, either by: (i) an analytical method, which will determine any critical speed in the range up to 1.2 VD, or (ii) any other approved method. (2) systematic flight tests to induce flutter at speeds up to VDF. These tests must show that a suitable margin of damping is available and that there is no rapid reduction of damping as VDF is approached. (3) flight tests to show that when approaching VDF: (i) control effectiveness around all three axes is not decreasing in an unusually rapid manner, and (ii) no signs of approaching aerofoil divergence of wings, tailplane and fuselage result from the trend of the static stabilities and trim conditions. CS 22.629 Flutter ED Decision 2003/13/RM (a) The sailplane must be free from flutter, aerofoil divergence, and control reversal in each configuration and at each appropriate speed up to at least VD. Sufficient damping must be available at any appropriate speed so that aeroelastic vibration dies away rapidly. (b) Compliance with sub-paragraph (a) must be shown by: (1) a ground vibration test which includes an analysis and an evaluation of the established vibration modes and frequencies for the purpose of recognising combinations critical for flutter, either by: (i) an analytical method, which will determine any critical speed in the range up to 1.2 VD, or (ii) any other approved method. (2) systematic flight tests to induce flutter at speeds up to VDF. These tests must show that a suitable margin of damping is available and that there is no rapid reduction of damping as VDF is approached. (3) flight tests to show that when approaching VDF: (i) control effectiveness around all three axes is not decreasing in an unusually rapid manner, and (ii) no signs of approaching aerofoil divergence of wings, tailplane and fuselage result from the trend of the static stabilities and trim conditions.