Airworthiness Directive · Amendment 39-17083 · Fuselage
The Boeing Company Airplanes
Superseded. A later AD replaced this one: AD 2016-13-10. Comply with the one in force.
This AD applies to The Boeing Company Model 737-300, -400, and -500 series airplanes, certificated in any category; as identified in Boeing Service Bulletin 737-53A1293, Revision 2, dated August 10, 2011.
We are superseding an existing airworthiness directive (AD) for certain The Boeing Company Model 737-300, -400, and -500 series airplanes. That AD currently requires repetitive external detailed inspections or non-destructive inspections to detect cracks in the fuselage skin along the chem-mill steps at stringers S-1 and S-2R, between station (STA) 400 and STA 460, and repair if necessary. This new AD adds inspections for cracking in additional fuselage skin locations, and repair if necessary. This new AD also reduces the inspection thresholds and repetitive intervals for certain airplanes. This AD was prompted by reports of additional crack findings of the fuselage skin at the chem-mill steps. We are issuing this AD to detect and correct fatigue cracking of the fuselage skin panels at the chem- mill steps, which could result in sudden fracture and failure of the fuselage skin panels, and consequent rapid decompression of the airplane.
At the applicable times specified in paragraph 1.E., “Compliance,” of Boeing Service Bulletin 737-53A1293, Revision 2, dated August 10, 2011, except as provided by paragraphs (j)(1) and (j)(2) of this AD: Do both a detailed inspection and a nondestructive inspection (NDI) (medium frequency eddy current, magneto optical imaging, C-scan, or ultrasonic phased array) to detect cracks in the fuselage skin along the chem-mill steps at stringers S-1 and S-2R, between station (STA) 400 and STA 460, in accordance with the Accomplishment Instructions of Boeing Service Bulletin 737-53A1293, Revision 2, dated August 10, 2011. Repeat the applicable inspections thereafter at intervals not to exceed those specified in paragraph 1.E., “Compliance,” of Boeing Service Bulletin 737-53A1293, Revision 2, dated August 10, 2011.
(1) If any crack is found during any inspection required by paragraph (g) of this AD, before further flight, repair in accordance with the Accomplishment Instructions of Boeing Service Bulletin 737-53A1293, Revision 2, dated August 10, 2011; except as provided by paragraph (h)(2) of this AD. Installation of a repair that meets the conditions specified in paragraph 1.E., “Compliance,” of Boeing Service Bulletin 737-53A1293, Revision 2, dated August 10, 2011, terminates the repetitive inspections required by paragraph (g) of this AD for the repaired area only.
(2) If any crack is found during any inspection required by paragraph (g) of this AD and Boeing Service Bulletin 737-53A1293, Revision 2, dated August 10, 2011, specifies to contact Boeing for repair: Before further flight, repair using a method approved in accordance with the procedures specified in paragraph (l) of this AD.
Accomplishing a modification of the chem-milled steps at any location identified in Boeing Service Bulletin 737-53A1293, Revision 2, dated August 10, 2011, using a method approved in accordance with the procedures specified in paragraph (l)(1) of this AD, terminates the repetitive inspections required by paragraph (g) of this AD for the modified area only.
(1) Where Boeing Service Bulletin 737-53A1293, Revision 2, dated August 10, 2011, specifies a compliance time relative to the date of Boeing Alert Service Bulletin 737-53A1293, Revision 1, dated July 7, 2010, this AD requires compliance within the specified compliance time after the effective date of this AD.
(2) Where the Condition column of paragraph 1.E., “Compliance,” of Boeing Service Bulletin 737-53A1293, Revision 2, dated August 10, 2011, specifies a condition based on whether an airplane has or has not been inspected, this AD bases the condition on whether an airplane has or has not been inspected as of the effective date of this AD.
(3) The post-repair inspection specified in Tables 4 and 6 of paragraph 1.E., “Compliance,” of Boeing Service Bulletin 737-53A1293, Revision 2, August 10, 2011, is not required by this AD.
Note 1 to paragraph (j)(3) of this AD: The damage tolerance inspections specified in Tables 4 and 6 of paragraph 1.E., “Compliance,” of Boeing Service Bulletin 737-53A1293, Revision 2, August 10, 2011, may be used in support of compliance with section 121.1109(c)(2) or 129.109(c)(2) of the Federal Aviation Regulations (14 CFR 121.1109(c)(2) or 14 CFR 129.109(c)(2)).
