AD 89-14-06

89-14-06 BOEING: Amendment 39-6252. Applicability: Model 757 and 767 series airplanes, identified in Boeing Alert Service Bulletins 757-28A0018 and 767-28A0020, both dated September 15, 1988, certificated in any category.

Compliance: Required as indicated, unless previously accomplished.

To prevent freezing of motor-driven fuel valve actuators caused by moisture ingress around corroded mating joint seals, accomplish the following:

A. For Model 757 series airplanes: Within the next 60 days after the effective date of this AD, visually inspect the left and right engine fuel shutoff valve actuators, engine fuel crossfeed valve actuator, and Auxiliary Power Unit (APU) fuel shutoff valve actuator for aluminum oxide corrosion residue on actuator screw heads and joining surfaces of the actuator body, in accordance with Boeing Alert Service Bulletin 757-28A0018, dated September 15, 1988. Any corroded actuator found must be replaced, prior to further flight, with a serviceable part; or as an alternative, a corroded actuator may be exchanged with a non-corroded actuator from a defuel valve position.

B. For Model 767 series airplanes: Within the next 60 days after the effective date of this AD, visually inspect the left and right engine fuel shutoff valve actuators, engine fuel crossfeed valve actuator, Auxiliary Power Unit (APU) fuel shutoff valve actuator, and APU fuel isolation valve actuator for aluminum oxide corrosion residue on actuator screw heads and joining surfaces of the actuator body, in accordance with Boeing Alert Service Bulletin 767- 28A0020 dated September 15, 1988. Any corroded actuator found must be replaced, prior to further flight, with a serviceable part; or as an alternative, a corroded actuator may be exchanged with a non-corroded actuator from a defuel valve position.

C. Within one year after the effective date of this AD, replace all fuel valve actuators with modified valve actuators, in accordance with Boeing Alert Service Bulletin 757-28A0018 dated September 15, 1988, for Model 757 series airplanes, and Boeing Alert Service Bulletin 767-28A0020 dated September 15, 1988, for Model 767 series airplanes.

D. An alternate means of compliance or adjustment of the compliance time, which provides an acceptable level of safety, may be used when approved by the Manager, Seattle Aircraft Certification Office, FAA, Northwest Mountain Region.

NOTE: The request should be forwarded through an FAA Principal Maintenance Inspector (PMI), who will either concur or comment and then send it to the Manager, Seattle Aircraft Certification Office.

E. Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate airplanes to a base in order to comply with the requirements of this AD.

All persons affected by this directive who have not already received the appropriate service documents from the manufacturer may obtain copies upon request to Boeing Commercial Airplanes,P.O. Box 3707, Seattle, Washington 98124. These documents may be examined at the FAA, Northwest Mountain Region, Transport Airplane Directorate, 17900 Pacific Highway South, Seattle, Washington, or Seattle Aircraft Certification Office, 9010 East Marginal Way South, Seattle, Washington.

This amendment (39-6252, AD 89-14-06) becomes effective on August 2, 1989.