Airworthiness Directives; Boeing Model 737-300, -400, and -500 Series Airplanes

This amendment adopts a new airworthiness directive (AD), applicable to all Boeing Model 737-300, -400, and -500 series airplanes, that requires replacement of the existing autothrottle computer with a new, improved autothrottle computer. This amendment is prompted by reports of asymmetric thrust conditions during flight caused by irregular autothrottle operation in which the thrust levers slowly move apart causing the airplane to bank excessively and go into a roll. The actions specified by this AD are intended to prevent such conditions, which could result in loss of control of the airplane.