Airworthiness Directive · Amendment 39-17442 · Fuselage
The Boeing Company Airplanes
(1) This AD applies to The Boeing Company Model 737-200, -200C, -300, -400, and -500 series airplanes; certificated in any category; as specified in Boeing Alert Service Bulletin 737-53A1255, Revision 2, dated August 7, 2012.
(2) Installation of Supplemental Type Certificate (STC) ST01219SE (http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgstc.nsf/0/2C6E3DBDDD36F91C862576A4005D64E2?OpenDocument&Highlight=st01219se) 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 an existing airworthiness directive (AD) for certain The Boeing Company Model 737-200, -200C, -300, -400, and - 500 series airplanes. That AD currently requires a one-time mid- frequency eddy current (MFEC) inspection, a low-frequency eddy current (LFEC) inspection, and a detailed inspection for damage or cracking of stringer S-4L and S-4R lap joints and stringer clips between body station (BS) 540 and BS 727, and follow-on inspections and repair if necessary. This new AD instead requires repetitive external eddy current inspections for cracking of certain fuselage crown lap joints, and corrective actions if necessary; internal eddy current and detailed inspections for cracking of certain fuselage crown lap joints, and repair if necessary; and detailed inspections of certain stringer clips, and replacement with new stringer clips if necessary. This AD also adds airplanes to the applicability. This AD was prompted by reports of cracking of the lap joint lower row. We are issuing this AD to detect and correct cracking of the fuselage lap joints, which could result in sudden decompression of the airplane.
For airplanes on which the lap splice modification specified in AD 2002-07-08, Amendment 39-12702 (67 FR 17917, April 12, 2002), has not been accomplished, except as required by paragraphs (l)(1) and (l)(2) of this AD: At the applicable times specified in paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1255, Revision 2, dated August 7, 2012, do an external eddy current inspection for cracking in the crown lap joints, except as provided by paragraphs (h) and (j) of this AD, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1255, Revision 2, dated August 7, 2012. At the intervals specified in paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1255, Revision 2, dated August 7, 2012, repeat the inspections, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1255, Revision 2, dated August 7, 2012. If any cracking is found in a lap joint, before further flight, repair, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1255, Revision 2, dated August 7, 2012.
As an option to confirm cracks found between tear straps during the inspections required by paragraph (g) of this AD, do an internal mid-frequency eddy current (MFEC) inspection for cracking in the lap joint fastener row between tear straps of the crown lap and do a detailed inspection of the lap joint lower fastener row for cracking, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1255, Revision 2, dated August 7, 2012.
For airplanes on which the lap splice modification specified in AD 2002-07-08, Amendment 39-12702 (67 FR 17917, April 12, 2002), has not been accomplished: At the times specified in paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1255, Revision 2, dated August 7, 2012, except as required by paragraphs (l)(1) and (l)(2) of this AD, do an internal MFEC, low frequency eddy current (LFEC), and detailed inspection for cracking in the crown lap joints and stringer clips, except as provided by paragraph (j) of this AD, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1255, Revision 2, dated August 7, 2012.
(1) If any cracking is found in any lap joint, before further flight, repair, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1255, Revision 2, dated August 7, 2012.
(2) If any cracking is found in any stringer clip, before further flight, replace the stringer clip with a new stringer clip, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1255, Revision 2, dated August 7, 2012.
As an option to confirm cracks found at tear strap locations while doing the inspections required by paragraph (g) or (i) of this AD, do an open-hole inspection for cracking at the tear strap locations, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1255, Revision 2, dated August 7, 2012.
(1) Accomplishing a repair of a crown lap joint in accordance with Boeing Alert Service Bulletin 737-53A1255, Revision 2, dated August 7, 2012, terminates the inspections required by paragraphs (g) and (i) of this AD for the repaired area only.
(2) Accomplishing the modification of the crown lap joints in accordance with any of the service bulletins specified in paragraphs (k)(2)(i), (k)(2)(ii), and (k)(2)(iii) of this AD terminates the inspections required by paragraphs (g) and (i) of this AD for the modified area only.
(i) Boeing Service Bulletin 737-53A1177, Revision 4, dated September 2, 1999.
(ii) Boeing Service Bulletin 737-53A1177, Revision 5, dated February 15, 2001.
(iii) Boeing Service Bulletin 737-53A1177, Revision 6, dated May 31, 2001.
(1) Where paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1255, Revision 2, dated August 7, 2012, specifies a compliance time “from the Revision 1 date of this service bulletin,” this AD requires a compliance time “after the effective date of this AD.”
(2) Where the “Condition” column, in paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1255, Revision 2, dated August 7, 2012, specifies airplanes with certain flight cycles “at the Revision 1 date of this service bulletin,” for this AD the condition is for airplanes with corresponding flight cycles “as of the effective date of this AD.”
