Airworthiness Directive · Amendment 39-15781 · Boeing Model 737-600, -700, -700C, -800, and -900 Series Airplanes
Boeing Model 737-600, -700, -700C, -800, and -900 Series Airplanes
This AD applies to Boeing Model 737-600, -700, -700C, -800, and -900 series airplanes, certificated in any category; on which Boeing Alert Service Bulletin 737-28A1206 has been accomplished.
This document publishes in the Federal Register an amendment adopting airworthiness directive (AD) 2008-24-51 that was sent previously to all known U.S. owners and operators of Boeing Model 737- 600, -700, -700C, -800, and -900 series airplanes by individual notices. This AD requires accomplishing a wiring test of the autoshutoff system to verify continuity and a visual verification that the wiring is correctly installed; doing corrective actions, if necessary; and doing a functional test of the autoshutoff system, and applicable maintenance actions. This AD is prompted by a report of a failure of the left-hand fuel pump of the center wing tank to shut off after being selected "OFF" by the flightcrew during flight on a Boeing Model 737-700 series airplane. Subsequent to that report, the failure was found on two additional airplanes. We are issuing this AD to prevent extended dry-running of the fuel pump, which could lead to localized overheating of parts inside the fuel pump, and which could produce an ignition source inside the fuel tank.
You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.
Within 48 clock-hours after the effective date of this AD, or prior to further flight, whichever occurs later: Except as provided by paragraphs (g) and (h) of this AD, do the autoshutoff system wiring test specified in paragraphs (f)(1) through (f)(10) of this AD.
(1) Remove electrical power from the airplane.
(2) Open the following circuit breakers, and install collars and 'DO-NOT-CLOSE' tags on the circuit breakers.
(i) Circuit breaker (CB) C3012, XFR BUS 2 SECT 2, on the P92 panel.
(ii) CB C3002, XFR BUS 1 SECT 2, on the P91 panel.
(iii) CB C1639, Fuel Auto S/O BST PUMP CTR TNK L AC, on the P6-3 panel.
(3) Verify continuity between TB5060F in terminal 5 and the bus side terminal of CB C1639 in the P6-3 circuit breaker panel.
(4) Check that wire number W0040-6402-14 is installed in terminal 5 of TB5060F.
(5) If, during the action required by paragraph (f)(3) of this AD, there is no continuity; or if, during the check required by paragraph (f)(4) of this AD, the wire is found not installed in TB5060F terminal 5: Before further flight, trace wire W0040-6402-14 from CB C1639 and re-terminate the other end of the wire to TB5060F terminal 5. After re-terminating the wire, before further flight, do the actions specified in paragraphs (f)(3) and (f)(4) of this AD.
(6) Remove the tags and collars from the following circuit breakers and close the circuit breakers.
(i) CB C3012, XFR BUS 2 SECT 2, on the P92 panel.
(ii) CB C3002, XFR BUS 1 SECT 2, on the P91 panel.
(iii) CB C1639, Fuel Auto S/O BST PUMP CTR TNK L AC, on the P6-3 panel.
(7) Supply electrical power to the airplane.
(8) Verify the voltage at CB C1639 is 115 volts alternating current +/−5 volts.
(9) If the voltage is not within the limits specified in paragraph (f)(8) of this AD, before further flight, repeat the actions required by paragraphs (f)(1) through (f)(8) of this AD.
(10) Test the autoshutoff system as follows:
(i) On P5-4 panel, switch Bus Transfer to OFF.
(ii) Using only one power source (auxiliary power unit (APU) or an engine generator), power only AC Bus 1 with no power to AC Bus 2.
(iii) Do the “Center Tank Boost Pump Auto Shutoff Functional Test” in accordance with paragraphs 9.A. through 9.G. of Task 28-22-00-720-805 of the Boeing 737-600/700/800/900 Aircraft Maintenance Manual, Document D633A101, Revision 37, dated October 15, 2008. Accomplishment of paragraphs 9.H. and 9.I. of the functional test should not be accomplished.
(iv) If the autoshutoff test fails the test required by paragraph (f)(10)(iii) of this AD: Within 48 clock-hours after the effective date of this AD, or before further flight, whichever occurs later, do either paragraph (f)(10)(iv)(A) or (f)(10)(iv)(B) of this AD.
(A) Do all applicable maintenance actions in accordance with Chapter 28, Section 28-22, of the Boeing 737-600/700/800/900 Fault Isolation Manual, Document D633A103, Revision 37, dated October 15, 2008, and repeat the action required by paragraph (f)(10)(iii) of this AD.
(B) Deactivate the left-hand fuel pump of the CWT as specified in paragraph (g) of this AD.
Deactivation of the left-hand fuel pump of the CWT and operation in accordance with Item 28-02, ‘Fuel Boost Pumps (Center Tank), of the Federal Aviation Administration Master Minimum Equipment List for Boeing 737 100/200/300/400/500/600/700/800/900, Revision 52, dated April 29, 2008, may be accomplished in lieu of the requirements of paragraph (f) of this AD until the left-hand fuel pump of the CWT is reactivated. If the pump is deactivated, dispatch under this configuration is allowed for 10 days. For airplanes on which the left-hand fuel pump of the CWT is deactivated under the provision of this paragraph: Prior to further flight after reactivating the pump, do the autoshutoff system wiring test and applicable corrective actions specified in paragraphs (f)(1) through (f)(10) of this AD.
Accomplishing the installation of the power failed ‘ON’ protection system (i.e., uncommanded pump “ON” protection system) for the center tank fuel boost pump in accordance with Boeing Alert Service Bulletin 737-28A1248, dated December 21, 2006; or Revision 1, dated January 9, 2008; terminates the autoshutoff system wiring test required by paragraphs (f) and (g) of this AD.
(i) Submit a report of the findings (both positive and negative) of the actions required by paragraph (f) of this AD to Boeing via e-mail at RSE.BOECOM@BOEING.COM; or via fax at (206) 766-5682; at the applicable time specified in paragraph (i)(1) or (i)(2) of this AD. The report must include: a description of the test failure; a description of the action taken to correct the failure; the total number of flight cycles/flight hours accumulated on the airplane at the time of inspection; and the date of accomplishment of Boeing Alert Service Bulletin 737-28A1206 and total number of flight hours/flight cycles accumulated on the airplane on the date of accomplishment of that service bulletin. Under the provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.), the Office of Management and Budget (OMB) has approved the information collection requirements contained in this AD and has assigned OMB Control Number 2120-0056.
(1) If the test is done after the effective date of this AD: Submit the report within 10 days after accomplishing the test.
(2) If the test was accomplished prior to the effective date of this AD: Submit the report within 10 days after the effective date of this AD.
