The A340-600 has accelerometers installed in the outer engine pylons. They are used by the flight control laws (through small aileron defelections) to damp a vertical bending mode of the wing (long and bendy !) which couples with a lateral mode of the forward fuselage (also long and bendy !). In testing and route proving this lateral mode in the forward fuselage was found to be very uncomfortable (the human body does not like lateral 'g'). The problem is only really noticed in turbulence. Since we put the First Class people in the forward part of the long bendy fuselage, comfort is quite important ! Incidentally the Boeing 777-300 also suffers from the same problem - lateral 'g' in the forward cabin in tubulence - don't know if the reason is the same.