AD 2012-23-04

This paragraph restates the requirements of paragraph (a) of AD 95-12-17, Amendment 39-9268 (60 FR 36981, July 19, 1995), with revised service information. For Model 737-100 and -200 series airplanes having line numbers 1 through 999 inclusive, on which the BS 727 frame upper outboard chord has been replaced as specified in Boeing Service Bulletin 737-53-1088: Prior to the accumulation of 30,000 flight cycles since replacement of the upper outboard chord, or within 4,500 flight cycles after August 18, 1995 (the effective date of AD 95-12-17) whichever occurs later, perform close visual, pulse echo shear wave (PESW), and high frequency eddy current (HFEC) inspections to detect cracks in the outboard chord of the frame at BS 727, in accordance with Part I of the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1166, dated June 30, 1994; Boeing Service Bulletin 737-53A1166, Revision 1, dated May 25, 1995; or Boeing Alert Service Bulletin 737-53A1166, Revision 2, dated May 25, 2006; as applicable. As of the effective date of this AD, use only Boeing Alert Service Bulletin 737-53A1166, Revision 2, dated May 25, 2006, to accomplish the actions required by this paragraph.

This paragraph restates the requirements of paragraph (b) of AD 95-12-17, Amendment 39-9268 (60 FR 36981, July 19, 1995), with revised service information. For Model 737-100 and -200 series airplanes having line numbers 1 through 999 inclusive, on which the BS 727 frame upper outboard chord has been replaced as specified in Boeing Service Bulletin 737-53-1088: Repeat the inspections required by paragraph (g) of this AD at the time specified in paragraphs (h)(1), (h)(2), (h)(3), and (h)(4) of this AD, as applicable, until the optional terminating action described in paragraph (r) of this AD is accomplished.

(1) If, at the time of the most recent inspection required by paragraph (g) or (h) of this AD, the airplane has accumulated 27,000 or more flight cycles, but fewer than 50,000 flight cycles since the replacement of the outboard chord: Perform the next inspection within 15,000 flight cycles. Repeat the inspection thereafter at intervals not to exceed 15,000 flight cycles until the airplane has accumulated 50,000 or more flight cycles since the replacement of the outboard chord. Do the inspections required by paragraph (h)(2) of this AD at the time specified.

(2) If, at the time of the most recent inspection required by paragraph (g) or (h) of this AD, the airplane has accumulated 50,000 or more flight cycles, but fewer than 60,000 flight cycles, since the replacement of the outboard chord: Perform the next inspection within 7,500 flight cycles. Repeat the inspection thereafter at intervals not to exceed 7,500 flight cycles until the airplane has accumulated 60,000 or more flight cycles since the replacement of the outboard chord. Do the inspections required by paragraph (h)(3) of this AD at the time specified.

(3) If, at the time of the most recent inspection required by paragraph (g) or (h) of this AD, the airplane has accumulated 60,000 or more flight cycles, but fewer than 70,000 flight cycles, since the replacement of the outboard chord: Perform the next inspection within 5,000 flight cycles. Repeat the inspection thereafter at intervals not to exceed 5,000 flight cycles until the airplane has accumulated 70,000 or more flight cycles since the replacement of the outboard chord. Do the inspections required by paragraph (h)(4) of this AD at the time specified.

(4) If, at the time of the most recent inspection required by paragraph (g) or (h) of this AD, the airplane has accumulated 70,000 or more flight cycles since replacement of the outboard chord: Perform the next inspection within 3,000 flight cycles. Repeat the inspection thereafter at intervals not to exceed 3,000 flight cycles.

This paragraph restates the requirements of paragraph (c) of AD 95-12-17, Amendment 39-9268 (60 FR 36981, July 19, 1995), with revised service information. For Model 737-100 and -200 series airplanes having line numbers 1 through 999 inclusive, on which the BS 727 frame outboard chord has not been replaced, or on which only the lower outboard chord has been replaced as specified in Boeing Service Bulletin 737-53-1088: Perform close visual, PESW, and HFEC inspections to detect cracks in the outboard chord of the frame at BS 727, in accordance with Part I of the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1166, dated June 30, 1994; Boeing Service Bulletin 737-53A1166, Revision 1, dated May 25, 1995; or Boeing Alert Service Bulletin 737-53A1166, Revision 2, dated May 25, 2006; as applicable. As of the effective date of this AD, use only Boeing Alert Service Bulletin 737-53A1166, Revision 2, dated May 25, 2006, to accomplish the actions required by this paragraph. Perform these inspections initially at the time specified in paragraph (i)(1), (i)(2), (i)(3), or (i)(4) of this AD, as applicable.

(1) For airplanes that have accumulated 27,000 or more total flight cycles, but fewer than 50,000 total flight cycles, as of August 18, 1995 (the effective date of AD 95-12-17, Amendment 39-9268 (60 FR 36981, July 19, 1995)): Inspect within 4,500 flight cycles after August 18, 1995.

(2) For airplanes that have accumulated 50,000 or more total flight cycles, but fewer than 60,000 total flight cycles, as of August 18, 1995 (the effective date of AD 95-12-17, Amendment 39-9268 (60 FR 36981, July 19, 1995)): Inspect within 2,500 flight cycles after August 18, 1995.

(3) For airplanes that have accumulated 60,000 or more total flight cycles, but fewer than 70,000 total flight cycles as of August 18, 1995 (the effective date of AD 95-12-17, Amendment 39-9268 (60 FR 36981, July 19, 1995)): Inspect within 1,500 flight cycles after August 18, 1995.

(4) For airplanes that have accumulated 70,000 or more total flight cycles as of August 18, 1995 (the effective date of AD 95-12-17, Amendment 39-9268 (60 FR 36981, July 19, 1995)): Inspect within 500 flight cycles or 90 days after August 18, 1995, whichever occurs first.

This paragraph restates the requirements of paragraph (d) of AD 95-12-17, Amendment 39-9268 (60 FR 36981, July 19, 1995), with revised service information. For Model 737-100 and -200 series airplanes having line numbers 1 through 999 inclusive, on which the BS 727 frame outboard chord has not been replaced, or on which only the lower outboard chord has been replaced as specified in Boeing Service Bulletin 737-53-1088: Repeat the inspections required by paragraph (i) of this AD at the time specified in paragraphs (j)(1), (j)(2), (j)(3), and (j)(4) of this AD, as applicable, until the optional terminating action described in paragraph (r) of this AD is accomplished.

(1) If, at the time of the most recent inspection required by paragraph (i) or (j) of this AD, the airplane has accumulated 27,000 or more total flight cycles, but fewer than 50,000 total flight cycles: Perform the next inspection within 15,000 flight cycles. Repeat the inspection thereafter at intervals not to exceed 15,000 flight cycles until the airplane has accumulated 50,000 or more total flight cycles. Do the inspections required by paragraph (j)(2) of this AD at the time specified.

(2) If, at the time of the most recent inspection required by paragraph (i) or (j) of this AD, the airplane has accumulated 50,000 or more total flight cycles, but fewer than 60,000 total flight cycles: Perform the next inspection within 7,500 flight cycles. Repeat the inspection thereafter at intervals not to exceed 7,500 flight cycles until the airplane has accumulated 60,000 or more total flight cycles. Do the inspections required by paragraph (j)(3) of this AD at the time specified.

(3) If, at the time of the most recent inspection required by paragraph (i) or (j) of this AD, the airplane has accumulated 60,000 or more total flight cycles, but fewer than 70,000 total flight cycles: Perform the next inspection within 5,000 flight cycles. Repeat the inspection thereafter at intervals not to exceed 5,000 flight cycles until the airplane has accumulated 70,000 or more total flight cycles. Do the inspections required by paragraph (j)(4) of this AD at the time specified.

(4) If, at the time of the most recent inspection required by paragraph (i) or (j) of this AD, the airplane has accumulated 70,000 or more total flight cycles: Perform the next inspection within 3,000 flight cycles. Repeat the inspection thereafter at intervals not to exceed 3,000 flight cycles.

This paragraph restates the requirements of paragraph (f) of AD 95-12-17, Amendment 39-9268 (60 FR 36981, July 19, 1995), with revised service information. If any crack is found in the outboard chord of the frame at BS 727 during any inspection required by paragraphs (g) through (j) of this AD, accomplish paragraph (k)(1) or (k)(2) of this AD, as applicable, in accordance with Boeing Alert Service Bulletin 737-53A1166, dated June 30, 1994; Boeing Service Bulletin 737-53A1166, Revision 1, dated May 25, 1995; or Boeing Alert Service Bulletin 737-53A1166, Revision 2, dated May 25, 2006; as applicable. As of the effective date of this AD, use only Boeing Alert Service Bulletin 737-53A1166, Revision 2, dated May 25, 2006, to accomplish the actions required by this paragraph.

Note 1 to paragraph (k) of this AD: Boeing Alert Service Bulletin 737-53A1166, dated June 30, 1994; Boeing Service Bulletin 737-53A1166, Revision 1, dated May 25, 1995; and Boeing Alert Service Bulletin 737-53A1166, Revision 2, dated May 25, 2006; refer to either Boeing Service Bulletin 737-53-1088, dated December 14, 1989; or Boeing Service Bulletin 737-53-1088, Revision 1, dated May 25, 2006; as an additional source of guidance for procedures to replace the chord.

(1) For any crack that extends from the forward edge of the chord or from the forward fastener hole, but that does not extend past the second fastener hole, accomplish the actions specified in either paragraph (k)(1)(i) or (k)(1)(ii) of this AD. Thereafter, perform initial and repetitive inspections in accordance with paragraphs (g) and (h) of this AD.

(i) Prior to further flight, install the time limited repair. Within 4,500 flight cycles or within 18 months after accomplishing the time-limited repair, whichever occurs first, replace the outboard chord. Or

(ii) Prior to further flight, replace the outboard chord.

(2) For any crack that extends from the forward edge of the chord, or from the forward fastener hole, and that extends past the second fastener hole, prior to further flight, replace the outboard chord. Thereafter, perform initial and repetitive inspections in accordance with paragraphs (g) and (h) of this AD.

For airplanes identified in table 5 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1166, Revision 2, dated May 25, 2006: Before the accumulation of 27,000 total flight cycles, or within 5,000 flight cycles after the effective date of this AD, whichever occurs later, do internal detailed and HFEC inspections to detect cracks in the auxiliary chord radius of the frame at BS 727, in accordance with Part 1 of the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1166, Revision 2, dated May 25, 2006. Repeat the inspections thereafter at intervals not to exceed 15,000 flight cycles until the optional terminating action described in paragraph (r) of this AD is accomplished. If any crack is found, before further flight, repair in accordance with the requirements of paragraph (s) of this AD.

For airplanes identified in table 2 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1166, Revision 2, dated May 25, 2006: Do the applicable inspections required by paragraph (m)(1) or (m)(2) of this AD at the time specified, in accordance with Part 1 of the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1166, Revision 2, dated May 25, 2006. Except as required by paragraph (p) of this AD, if any crack is found during any inspection required by paragraph (m)(1) or (m)(2) of this AD, before further flight, repair in accordance with Part 3 or Part 4 of the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1166, Revision 2, dated May 25, 2006, as applicable. Repeat the inspections until the optional terminating action described in paragraph (r) of this AD is accomplished. Accomplishing the inspections in this paragraph ends the inspections required by paragraphs (i) and (j) of this AD.

(1) For airplanes on which the inspections specified in Boeing Alert Service Bulletin 737-53A1166, dated June 30, 1994; or Boeing Service Bulletin 737-53A1166, Revision 1, dated May 25, 1995; have not been performed as of the effective date of this AD: Do the inspections required by paragraphs (m)(1)(i) and (m)(1)(ii) of this AD at the time specified.

(i) Before the accumulation of 27,000 total flight cycles, or within 5,000 flight cycles after the effective date of this AD, whichever occurs later: Do ultrasonic and surface HFEC inspections to detect cracks in the forward flange of the outboard chord of the frame at BS 727. Repeat the inspections thereafter at intervals not to exceed 5,000 flight cycles.

(ii) Before the accumulation of 27,000 total flight cycles, or within 10,000 flight cycles after the effective date of this AD, whichever occurs later: Do an open hole eddy current inspection to detect cracks in the forward flange of the outboard chord of the frame at BS 727. Repeat the inspection thereafter at intervals not to exceed 15,000 flight cycles.

(2) For airplanes on which the inspections specified in Boeing Alert Service Bulletin 737-53A1166, dated June 30, 1994; or Boeing Service Bulletin 737-53A1166, Revision 1, dated May 25, 1995; have been performed as of the effective date of this AD: Repeat the applicable inspection specified in paragraphs (m)(1)(i) and (m)(1)(ii) of this AD thereafter at intervals not to exceed 5,000 flight cycles for the ultrasonic and surface HFEC inspections, and at intervals not to exceed 15,000 flight cycles for the open hole eddy current inspection.

For airplanes identified in table 3 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1166, Revision 2, dated May 25, 2006: Do the applicable inspections required by paragraph (n)(1) or (n)(2) of this AD at the time specified, in accordance with Part 1 of the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1166, Revision 2, dated May 25, 2006. Except as required by paragraph (p) of this AD, if any crack is found during any inspection required by paragraph (n)(1) or (n)(2) of this AD, before further flight, repair in accordance with Part 3 or Part 4, as applicable, of the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1166, Revision 2, dated May 25, 2006. Repeat the inspections until the optional terminating action described in paragraph (r) of this AD is accomplished. Accomplishing the inspections in this paragraph ends the inspections required by paragraphs (g) and (h) of this AD. The detailed and eddy current inspections of the outboard chord of S-18A specified in Boeing Alert Service Bulletin 737-53A1166, Revision 2, dated May 25, 2006, are not required by this AD.

(1) For airplanes on which the inspections specified in Boeing Alert Service Bulletin 737-53A1166, dated June 30, 1994; or Boeing Service Bulletin 737-53A1166, Revision 1, dated May 25, 1995; have not been done as of the effective date of this AD: Do the inspections required by paragraphs (n)(1)(i) and (n)(1)(ii) of this AD at the time specified.

(i) Within 27,000 flight cycles since replacement of the upper outboard chord, or within 5,000 flight cycles after the effective date of this AD, whichever occurs later: Do ultrasonic, low frequency eddy current, and edge HFEC inspections to detect cracks in the forward flange of the outboard chord of the frame at BS 727. Repeat the inspections thereafter at intervals not to exceed 5,000 flight cycles.

(ii) Within 27,000 flight cycles since replacement of the upper outboard chord, or within 10,000 flight cycles after the effective date of this AD, whichever occurs later: Do an open hole eddy current inspection to detect cracks in the forward flange of the outboard chord of the frame at BS 727. Repeat the inspections thereafter at intervals not to exceed 15,000 flight cycles.

(2) For airplanes on which the inspections specified in Boeing Alert Service Bulletin 737-53A1166, dated June 30, 1994; or Boeing Service Bulletin 737-53A1166, Revision 1, dated May 25, 1995; have been done as of the effective date of this AD: Repeat the applicable inspection specified in paragraphs (n)(1)(i) and (n)(1)(ii) of this AD thereafter at intervals not to exceed 5,000 flight cycles for the ultrasonic, low frequency eddy current, and edge HFEC inspections, and at intervals not to exceed 15,000 flight cycles for the open hole eddy current inspection.

For airplanes identified in table 4 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1166, Revision 2, dated May 25, 2006: Within 60,000 flight cycles after accomplishing the modification of the outboard chord of the frame at BS 727 at S-18A, but no earlier than 50,000 flight cycles after accomplishing the modification; do a one-time follow-on open hole eddy current inspection to detect cracks in the modified chord, in accordance with Part 8 of the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1166, Revision 2, dated May 25, 2006. Except as required by paragraph (p) of this AD, if any crack is found during the inspection required by this paragraph, before further flight, repair in accordance with Part 3 or Part 4, as applicable, of the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1166, Revision 2, dated May 25, 2006.

If any crack is found during any inspection required by paragraphs (m), (n), or (o) of this AD, and the repairs specified in Part 3 and Part 4 of the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1166, Revision 2, dated May 25, 2006, cannot be installed using the procedures identified in this service bulletin: Before further flight, repair using a method approved in accordance with the procedures specified in paragraph (s) of this AD.

For any airplane on which a time-limited repair is installed on the outboard chord of the frame at body station BS 727 as specified in Boeing Alert Service Bulletin 737-53A1166, dated June 30, 1994; Boeing Service Bulletin 737-53A1166, Revision 1, dated May 25, 1995; or Boeing Alert Service Bulletin 737-53A1166, Revision 2, dated May 25, 2006: Within 4,500 flight cycles after installation of the repair, or within 6 months after the effective date of this AD, whichever occurs later, replace the repair in accordance with Part 9 of the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1166, Revision 2, dated May 25, 2006.

Accomplishment of the applicable action specified in paragraph (r)(1) or (r)(2) of this AD, in accordance with Part 2 of the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1166, dated June 30, 1994; Part II of the Accomplishment Instructions of Boeing Service Bulletin 737-53A1166, Revision 1, dated May 25, 1995; or Part 6 of the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1166, Revision 2, dated May 25, 2006; constitutes terminating action for the inspections required by paragraphs (g) through (o) this AD.

(1) Installation of the preventative modification.

(2) Replacement of the cracked chord and installation of the preventative modification.