Airworthiness Directive · Amendment 39-19420 · Fuselage
The Boeing Company Airplanes
(1) This AD applies to The Boeing Company Model 737-200, -300, -400, and -500 series airplanes, certificated in any category, as identified in Boeing Alert Service Bulletin 737-53A1254, Revision 3, dated November 13, 2017.
(2) Installation of Supplemental Type Certificate (STC) ST01219SE (http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgstc.nsf/0/ebd1cec7b301293e86257cb30045557a/$FILE/ST01219SE.pdf) does not affect the ability to accomplish the actions required by this AD. Therefore, for airplanes on which STC ST01219SE is installed, a “change in product” alternative method of compliance (AMOC) approval request is not necessary to comply with the requirements of 14 CFR 39.17.
We are superseding Airworthiness Directive (AD) 2010-25-06, which applied to certain The Boeing Company Model 737-200, -300, -400, and -500 series airplanes. AD 2010-25-06 required repetitive inspections for cracking of certain fuselage frames and stub beams, and corrective actions if necessary. AD 2010-25-06 also provided for an optional repair, which terminated the repetitive inspections. For airplanes on which a certain repair was done, AD 2010-25-06 also required repetitive inspections for cracking of certain fuselage frames and stub beams, and corrective actions if necessary. This AD retains the actions required by AD 2010-25-06 and expands the inspection area. This AD was prompted by additional cracking found in areas not covered by the inspections in AD 2010-25-06. We are issuing this AD to address the unsafe condition on these products.
At the applicable time specified in table 1 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1254, Revision 3, dated November 13, 2017: Do a detailed or high frequency eddy current (HFEC) inspection for cracking of the body station (BS) 616 and 639 frames and stub beams and do all applicable related investigative and corrective actions, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1254, Revision 3, dated November 13, 2017, except as required by paragraph (m)(1) of this AD. Do all applicable related investigative and corrective actions before further flight. Thereafter, repeat the inspection at the applicable time specified in table 1 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1254, Revision 3, dated November 13, 2017.
At the applicable time specified in table 2 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1254, Revision 3, dated November 13, 2017: Do the inspections required by paragraphs (h)(1) and (h)(2) of this AD; or the inspection required by paragraph (h)(3) of this AD; as applicable, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1254, Revision 3, dated November 13, 2017, except as required by paragraph (m)(1) of this AD. Do all applicable related investigative and corrective actions before further flight. Thereafter, repeat the inspection at the applicable time specified in table 2 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1254, Revision 3, dated November 13, 2017.
(1) Do a low frequency eddy current (LFEC) inspection of the web, and an HFEC inspection of the inner and outer chord common to the upper end fastener rows of the web splice doubler for cracking.
(2) Do the inspection specified in paragraph (h)(2)(i) or (h)(2)(ii) of this AD.
(i) Do a detailed inspection of the replacement frame section for cracking.
(ii) Do an HFEC and LFEC inspection of the replacement frame section for cracking.
(3) Do a detailed or HFEC inspection of the replacement stub beam for cracking.
For Group 1 and Group 2 airplanes as identified in Boeing Alert Service Bulletin 737-53A1254, Revision 3, dated November 13, 2017, at the time specified in table 3 or table 4, as applicable, of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1254, Revision 3, dated November 13, 2017, except as required by paragraph (m)(2) of this AD: Do the inspections required by paragraph (i)(1) and (i)(2) of this AD and all applicable corrective actions, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1254, Revision 3, dated November 13, 2017, except as required by paragraph (m)(1) of this AD. Do all applicable corrective actions before further flight. Thereafter, repeat the inspections at the time specified in table 3 or table 4, as applicable, of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1254, Revision 3, dated November 13, 2017.
(1) Do an open-hole HFEC inspection for cracking of the buttock line (BL) 45.5 longitudinal floor beam web at each fastener hole common to the stub beam attachment angle.
(2) Do an HFEC surface inspection for cracking of the BL 45.5 longitudinal floor beam web around the fastener head/tail at each fastener location common to the backup strap.
For Group 2 airplanes as identified in Boeing Alert Service Bulletin 737-53A1254, Revision 3, dated November 13, 2017, at the applicable time specified in table 5 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1254, Revision 3, dated November 13, 2017, except as required by paragraph (m)(2) of this AD: Do the inspections required by paragraphs (j)(1) and (j)(2) of this AD and all applicable corrective actions, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1254, Revision 3, dated November 13, 2017, except as required by paragraph (m)(1) of this AD. Do all applicable corrective actions before further flight. Thereafter, repeat the inspections at the applicable time specified in table 5 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1254, Revision 3, dated November 13, 2017.
(1) Do an open-hole HFEC inspection for cracking of the BL 45.5 longitudinal floor beam web filler at each fastener hole common to the stub beam attachment angle.
(2) Do an HFEC surface inspection for cracking of the BL 45.5 longitudinal floor beam web filler around the fastener head/tail at each fastener location common to the backup strap.
For Group 2 and Group 3 airplanes as identified in Boeing Alert Service Bulletin 737-53A1254, Revision 3, dated November 13, 2017, at the applicable time specified in table 9 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1254, Revision 3, dated November 13, 2017, except as required by paragraph (m)(2) of this AD; do detailed and medium frequency eddy current subsurface inspections for cracking of the BS 616 machined stub beam upper chord, and all applicable corrective actions, except as required by paragraph (m)(1) of this AD. Do all applicable corrective actions before further flight. Thereafter, repeat the inspections at the applicable time specified in table 9 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1254, Revision 3, dated November 13, 2017.
