Originally Posted by Lyman
Could the .5 second cycle .1g amplitude "vibration" have been a stammering elevator select? OR THS stutter? Just a mechanical question, nothing more.
The buffet onset envelope is determined in flight test before the type is released into service. It is scheduled in the AFM, the FCOM, the QRH and in the FMEGC. Stall warning is set to occur at an AoA 1 degree less than buffet onset. The recorded 'signature' matches that previously obtained in flight tests. Why would the elevator begin to stammer and/or the THS stutter at the precise moment that the airplane enters a regime where buffet is known to occur?