Airworthiness Directive · Amendment 39-17728 · Fuselage
the Boeing Company Airplanes
This AD applies to The Boeing Company Model 737-100, -200, -200C, -300, -400, and -500 series airplanes, certified in any category, as identified in Boeing Alert Service Bulletin 737-53A1322, dated November 5, 2012.
We are adopting a new airworthiness directive (AD) for certain the Boeing Company Model 737-100, -200, -200C, -300, -400, and -500 series airplanes. This AD was prompted by a report of cracks in stringer splices at body station STA 360 and STA 908, between stringer (S) S-10L and S-10R; cracks in butt straps between S-5L and S-3L, and S-3R and S-5R; vertical chem-mill fuselage skin cracks at certain butt joints; and an instance of cracking that occurred in all those three structural elements on one airplane. This AD requires repetitive inspections for any cracking of stringer splices and butt straps, and related corrective and investigative actions if necessary. We are issuing this AD to detect and correct cracking in the three structural elements, which could result in the airplane not being able to sustain limit load requirements and possibly result in uncontrolled decompression.
For Group 1 airplanes, as identified in Boeing Alert Service Bulletin 737-53A1322, dated November 5, 2012: At the compliance time specified in paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1322, dated November 5, 2012, except as provided by paragraph (j)(2) of this AD, inspect the stringers and butt straps and repair as applicable, using a method approved in accordance with the procedures specified in paragraph (k) of this AD.
For Groups 2 through 6 airplanes, as identified in Boeing Alert Service Bulletin 737-53A1322, dated November 5, 2012: At the applicable compliance time specified in paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1322, dated November 5, 2012, do the applicable inspections for cracking identified in paragraphs (h)(1) through (h)(4) of this AD, and all applicable corrective actions, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1322, dated November 5, 2012, except as provided by paragraph (j) of this AD. Do all applicable corrective actions before further flight. Thereafter, repeat the applicable inspections at the compliance times specified in paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1322, dated November 5, 2012. Accomplishing the corrective actions for a cracked stringer splice, as specified in Boeing Alert Service Bulletin 737-53A1322, dated November 5, 2012, terminates the repetitive inspections required by this paragraph for that stringer splice only.
(1) Internal detailed inspections of the stringer splices and butt straps.
(2) Internal high-frequency eddy current (HFEC) surface inspections of the butt straps.
(3) Internal low-frequency eddy current (LFEC) inspection of the butt straps.
(4) HFEC open hole rotary probe inspections of butt straps or of one location of a butt strap, as applicable.
The post-repair inspection specified in Table 11 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1322, dated November 5, 2012, is not required by this AD.
Note 1 to paragraph (i) of this AD: The post-repair inspections specified in Table 11 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1322, dated November 5, 2012, may be used in support of compliance with section 121.1109(c)(2) or 129.109(b)(2) of the Federal Aviation Regulations (14 CFR 121.1109(c)(2) or 14 CFR 129.109(b)(2)). The corresponding actions specified in the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1322, dated November 5, 2012, are not required by this AD.
(1) Where Boeing Alert Service Bulletin 737-53A1322, dated November 5, 2012, specifies to contact Boeing for appropriate action: Before further flight, repair using a method approved in accordance with the procedures specified in paragraph (k) of this AD.
(2) Where Boeing Alert Service Bulletin 737-53A1322, dated November 5, 2012, specifies a compliance time “after the original issue date of this service bulletin,” this AD requires compliance within the specified compliance time after the effective date of this AD.
(3) Where General Information Note 12 of the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1322, dated November 5, 2012, specifies contacting Boeing, this AD does not require the actions specified in that note.
