Airworthiness Directive · Amendment 39-12249 · Boeing Model 737, 757, and 767 Series Airplanes
Boeing Model 737, 757, and 767 Series Airplanes
Model 737, 757, and 767 series airplanes, certificated in any category, as listed in the following Boeing Service Bulletins: Table 1.--Effectivity Affected models/ Boeing Service Bulletin Date series 737-29A1073, Revision 3....... December 2, 1999. Model 737-100, -200, 300, -400, and -500. 737-29A1081................... December 2, 1999. Model 737-600, -700, and -800. 757-29A0048, Revision 3....... December 2, 1999. Model 757-200. 757-29A0051................... December 2, 1999. Model 757-300. 767-29A0083, Revision 4....... September 28, Model 767. 2000.
This amendment adopts a new airworthiness directive (AD), applicable to certain Boeing Model 737, 757, and 767 series airplanes. This AD requires repetitive operational checks of certain motor- operated hydraulic shutoff valves to detect malfunctioning; replacement with new valves, if necessary; and eventual replacement of certain existing valves with new valves, which terminates the repetitive inspections. This amendment is prompted by reports that various intermittent limit-switch problems have caused valve failures. The actions specified by this AD are intended to prevent failure of the motor-operated hydraulic shutoff valves, which could result in leakage of hydraulic fluid to the engine fire zone, reduced ability to retract the landing gear, loss of backup electrical power or other combinations of failures; and consequent reduced controllability of the airplane.
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
