AD 2013-07-09 Airworthiness Directives; The Boeing Company Airplanes

Models named: 737-700, -700C, -800, -900ER series, 747-400F series, 767-200, -300 series. Read the applicability below — it usually turns on serial or part numbers too.

This AD applies to The Boeing Company airplanes, certificated in any category, as identified in paragraphs (c)(1), (c)(2), and (c)(3) of this AD. (1) Model 737-700, -700C, -800, and -900ER series airplanes, as identified in Boeing Alert Service Bulletin 737-35A1121, Revision 1, dated November 7, 2011. (2) Model 747-400F series airplanes, as identified in Boeing Alert Service Bulletin 747-35A2126, Revision 1, dated September 29, 2011. (3) Model 767-200 and -300 series airplanes, as identified in Boeing Alert Service Bulletin 767-35A0057, Revision 1, dated November 17, 2011.

Comply with this AD within the compliance times specified, unless already done.

Within 24 months after the effective date of this AD: Do a general visual inspection to determine if the serial number of the crew oxygen mask stowage box unit is identified in the Appendix of Intertechnique Service Bulletin MXP1/4-35-175, Revision 2, dated May 10, 2011, in accordance with the Accomplishment Instructions of the applicable Boeing alert service bulletin specified in paragraph (c)(1), (c)(2), or (c)(3) of this AD. A review of airplane maintenance records is acceptable in lieu of this inspection if the serial number of the crew oxygen mask stowage box unit can be conclusively determined from that review. (1) If any crew oxygen mask stowage box unit has a serial number identified in table 1 of the Appendix of Intertechnique Service Bulletin MXP1/4-35-175, Revision 2, dated May 10, 2011: Before further flight, replace the crew oxygen mask stowage box unit with a new or serviceable unit, in accordance with the Accomplishment Instructions of the applicable Boeing alert service bulletin specified in paragraph (c)(1), (c)(2), or (c)(3) of this AD. (2) If any crew oxygen mask stowage box unit has a serial number identified in table 2 of the Appendix of Intertechnique Service Bulletin MXP1/4-35-175, Revision 2, dated May 10, 2011: Before further flight, add the letter “I” to the end of the serial number (identified as “SER”) on the identification label, in accordance with the Accomplishment Instructions of Intertechnique Service Bulletin MXP1/4-35-175, Revision 2, dated May 10, 2011; and reinstall in accordance with the Accomplishment Instructions of the applicable Boeing alert service bulletin specified in paragraph (c)(1), (c)(2), or (c)(3) of this AD. (3) If no crew oxygen mask stowage box unit has a serial number identified in the Appendix of Intertechnique Service Bulletin MXP1/4-35-175, Revision 2, dated May 10, 2011: Unless a records review was done to determine the serial number, before further flight, reinstall the crew oxygen mask stowage box unit, in accordance with the Accomplishment Instructions of the applicable Boeing alert service bulletin specified in paragraph (c)(1), (c)(2), or (c)(3) of this AD.

This AD was prompted by reports indicating that certain crew oxygen mask stowage box units were possibly delivered with a burr in the inlet fitting. The burr might break loose during test or operation, and might pose an ignition source or cause an inlet valve to jam. We are issuing this AD to prevent an ignition source, which could result in an oxygen-fed fire; or an inlet valve jam in a crew oxygen mask stowage box unit, which could result in restricted flow of oxygen.

None.