Airworthiness Directive · Amendment 39-12007 · Boeing Model 737-300, -400, and -500 Series Airplanes
Boeing Model 737-300, -400, and -500 Series Airplanes
All Model 737-300, -400, and -500 series airplanes; certificated in any category.
Note 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (c) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.
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.
To prevent a severe asymmetric thrust condition during flight which could result in loss of control of the airplane, accomplish the following:
(a) Within 18 months after the effective date of this AD: Replace the existing autothrottle computer with a new, improved autothrottle computer in accordance with Boeing Alert Service Bulletin 737-22A1130, dated September 24, 1998.
(b) As of the effective date of this AD, no person shall install on any airplane, an autothrottle computer having part number 10-62017-1, -2, -3, -4, -5, -11, -21, -23, -25, or -27.
