How about a hypothetical conversation with an Airbus test pilot -
'Did you slam the rudder back and forth when testing the bus?'
'Yes, that's what test pilots do'
'Do you do it at different speeds'
'Yes, that's what test pilots do'
'How did you determine Va'
'We flew to the limits of mathematical fatigue to see if the math was right, examined the structure. Adjusted the numbers, butressed up the airframe if needed, that's what test pilots and engineers do'
'Do you think a left, right, then left application of rudder would take the tail off'
'If it did, then all the Airbus test pilots would be dead or better skydivers.'
'So what is the problem then?'
'Fatigued structure, bad engineering, a bad landing? Went through severe turbulance too many times, bad manufacuring that day, they put that tail on the day before Christmas. Temp issues with carbon fibre, the alumimum condensed moisture in there, maybe it's like the Alaska jack screw deal, mechanics signed the tail inspections off with out getting on a ladder, hydraulics too strong calibrated incorrect, slamming stops, terrorism, it did happen with an engine out...two failures at the same time...what are the odds of that?'
'so do you think the pilots screwed up?'
'Well what do you think an airline pilot could do departing on climbout, standard engine out procedure in a big whale that I couldn't do with an empty plane, both of us in parachutes over a test area trying to break the plane?'