2.3.5 Flutter and vibration
It shall be demonstrated by suitable tests that all parts of the
aeroplane are free from flutter and excessive vibration in all
aeroplane configurations under all speed conditions within the
operating limitations of the aeroplane (see 1.3.2). There shall
be no buffeting severe enough to interfere with control of the
aeroplane, to cause structural damage or to cause excessive
fatigue to the flight crew.