Airworthiness Directive · Amendment 39-17375 · Fuel
The Boeing Company Airplanes
This AD applies to The Boeing Company Model 777-200, -200LR, -300, and -300ER series airplanes, certificated in any category, as identified in Boeing Service Bulletin 777-28A0034, Revision 2, dated September 20, 2010.
We are adopting a new airworthiness directive (AD) for certain The Boeing Company Model 777-200, -200LR, -300, and -300ER series airplanes. This AD was prompted by fuel system reviews conducted by the manufacturer. This AD requires doing an inspection to identify the part number of the motor-operated valve (MOV) actuators of the main and center fuel tanks; replacing certain MOV actuators with new MOV actuators; and measuring the electrical resistance of the bond from the adapter plate to the airplane structure, and doing corrective actions if necessary. We are issuing this AD to prevent electrical current from flowing through an MOV actuator into a fuel tank, which could create a potential ignition source inside the fuel tank. This condition, in combination with flammable fuel vapors, could result in a fuel tank explosion and consequent loss of the airplane.
You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.
Except as provided by paragraph (l) of this AD: Within 60 months after the effective date of this AD, do an inspection of the MOV actuators of the main and center fuel tanks for part number (P/N) MA20A1001-1, in accordance with the Accomplishment Instructions of Boeing Service Bulletin 777-28A0034, Revision 2, dated September 20, 2010. A review of airplane maintenance records is acceptable in lieu of this inspection if the part number can be conclusively determined from that review.
Except as provided by paragraphs (k)(1) and (k)(2) of this AD, if any MOV actuator having P/N MA20A1001-1 is found during the inspection required by paragraph (g) of this AD, within 60 months after the effective date of this AD, replace the MOV actuator with either a new or serviceable MOV actuator having P/N MA30A1001, or with an MOV actuator that meets the criteria specified in paragraphs (h)(1) and (h)(2) of this AD; and, as applicable, measure the electrical resistance of the bond from the adapter plate to the airplane structure and do all applicable corrective actions; in accordance with the Accomplishment Instructions of Boeing Service Bulletin 777-28A0034, Revision 2, dated September 20, 2010. Do all applicable corrective actions before further flight.
(1) The replacement MOV actuator must be a Boeing part that is approved after the issuance of Boeing Service Bulletin 777-28A0034, Revision 2, dated September 20, 2010, by the Manager, Seattle Aircraft Certification Office (ACO), FAA; or the Boeing Commercial Airplanes Organization Designation Authorization (ODA) that has been authorized by the Manager, Seattle ACO, to approve the part.
(2) The replacement MOV actuator must be fully interchangeable with the part specified in Boeing Service Bulletin 777-28A0034, Revision 2, dated September 20, 2010.
As of the effective date of this AD, no person may install an MOV actuator, P/N MA20A1001-1, on any 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.
Aircraft
