Airworthiness Directive · Amendment 39-22292 · Fuel
The Boeing Company Airplanes
Superseded. A later AD replaced this one: AD 2023-07-09. Comply with the one in force.
This AD applies to The Boeing Company Model 747-400 and 747-8 series airplanes, certificated in any category, equipped with an activated horizontal stabilizer fuel tank.
The FAA is adopting a new airworthiness directive (AD) for certain The Boeing Company Model 747-400 and 747-8 series airplanes. This AD was prompted by reports of wear-through of the motor impeller inlet adapter of a transfer pump for the horizontal stabilizer fuel tank caused by contact between the pump inlet check valve and the inlet adapter. This AD requires inspecting for wear of the motor impeller inlet check valves and inlet adapters of the transfer pumps for the horizontal stabilizer fuel tank and doing corrective actions, if necessary. This AD also limits the installation of affected parts. The FAA is issuing this AD to address the unsafe condition on these products.
(1) A “serviceable” inlet adapter is an inlet adapter of the motor impeller assembly for which any missing material does not exceed 0.20 inch in the pump axial direction.
(2) A “serviceable” inlet check valve is an inlet check valve for which the hinge pin protrudes past the flapper arm on both sides and there is no metal disk gouging, missing material, corrosion, burrs, or raised material. Minor surface scratches, defects, or appearances of surface wear are acceptable.
(3) A horizontal stabilizer tank is considered to be “activated” if it is not deactivated by an approved alteration.
Within 90 days after the effective date of this AD: Do a detailed visual inspection of the inlet check valve in the left and right transfer pump housing for hinge pin protrusion, gouging, missing material, corrosion, burrs, and raised material, in accordance with paragraph C., Work Instructions, Attachment A, Boeing Multiple Operator Message MOM-MOM-22-0549-01B(R1), dated November 29, 2022.
(1) Condition 1: If the hinge pin does not protrude past the flapper arm on one side, or if any gouging, missing material, corrosion, burrs, or raised material is found on the inlet check valve, do the actions required by paragraphs (h)(1)(i) and (ii) of this AD.
(i) Report inspection findings in accordance with paragraph (j) of this AD.
(ii) Prior to further flight, replace the inlet check valve or transfer pump housing with a serviceable inlet check valve or transfer pump housing containing a serviceable inlet check valve, in accordance with paragraph C., Work Instructions, Attachment A, Boeing Multiple Operator Message MOM-MOM-22-0549-01B(R1), dated November 29, 2022.
(2) Condition 2: If the hinge pin does protrude past the flapper arm on both sides, and no gouging, missing material, corrosion, burrs, or raised material is found, report inspection findings in accordance with paragraph (j) of this AD.
Within 90 days after the effective date of this AD: Do a detailed visual inspection of the transfer pump motor impeller inlet adapter for wear (missing material), in accordance with paragraph D., Work Instructions, Attachment A, Boeing Multiple Operator Message MOM-MOM-22-0549-01B(R1), dated November 29, 2022.
(1) Condition 1: If any wear is found that is 0.20 inch or less, report inspection findings in accordance with paragraph (j) of this AD.
(2) Condition 2: If any wear is found that is greater than 0.20 inch, do the actions required by paragraphs (i)(2)(i) and (ii) of this AD.
(i) Report inspection findings in accordance with paragraph (j) of this AD.
(ii) Before further flight, replace the transfer pump motor impeller with a transfer pump motor impeller having a serviceable inlet adapter, in accordance with paragraph D., Work Instructions, Attachment A, Boeing Multiple Operator Message MOM-MOM-22-0549-01B(R1), dated November 29, 2022.
At the applicable time specified in paragraph (j)(1) or (2) of this AD, submit a report of all findings of the inspections required by paragraphs (h) and (i) of this AD, in accordance with paragraph G. and Appendix A, Attachment A, Boeing Multiple Operator Message MOM-MOM-22-0549-01B(R1), dated November 29, 2022.
(1) If the inspection was done on or after the effective date of this AD: Submit the report within 30 days after the inspection.
(2) If the inspection was done before the effective date of this AD: Submit the report within 30 days after the effective date of this AD.
As of the effective date of this AD, no person may install, on any airplane, any transfer pump motor impeller inlet adapter or inlet check valve (or assembly containing either) for the horizontal stabilizer fuel tank, unless the affected part has been inspected as specified in paragraph (h) or (i) of this AD, as applicable, and been determined to be a serviceable part as defined in paragraph (g)(1) or (2) of this AD.
