Airworthiness Directive · Amendment 39-17270 · Fuselage
The Boeing Company Airplanes
(1) This AD applies to The Boeing Company Model 737-100, -200, -200C, -300, -400, and -500 series airplanes, certificated in any category, as identified in Boeing Alert Service Bulletin 737-53A1318, dated October 31, 2011.
(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. For all other AMOC requests, the operator must request approval for an AMOC in accordance with the procedures specified in paragraph (i) of this AD.
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 a crack found in the fuselage skin under the aft drain mast. This AD requires a detailed inspection for cracking and corrosion of the channel and fillers adjacent to the drain mast bolts, an inspection to determine the location of the bonding strap, a measurement of the washers under the drain mast bolts, and related investigative actions and repair if necessary. We are issuing this AD to detect and correct cracking in the fuselage skin and internal support structure, which could result in uncontrolled decompression of the airplane.
(1) For airplanes identified as Group 1 airplanes as specified in Boeing Alert Service Bulletin 737-53A1318, dated October 31, 2011: At the times specified in paragraph 1.E. “Compliance,” of Boeing Alert Service Bulletin 737-53A1318, dated October 31, 2011, do the actions specified in paragraphs (g)(1)(i), (g)(1)(ii), and (g)(1)(iii) of this AD, and do all related investigative actions and repair, as applicable, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1318, dated October 31, 2011, except as required by paragraph (h) of this AD. Related investigative actions and repairs must be done before further flight. If the drain mast is found to be installed correctly, no further action is required by this paragraph.
(i) Do a detailed inspection for cracking and signs of corrosion of the channel and the fillers adjacent to the drain mast bolts.
(ii) Inspect the bonding strap for the correct location.
(iii) Measure the diameter and thickness of the washers under the drain mast bolts.
(2) For airplanes identified as Group 2 airplanes as specified in Boeing Alert Service Bulletin 737-53A1318, dated October 31, 2011: Within 120 days after the effective date of this AD, inspect and repair, as required, using a method approved in accordance with the procedures specified in paragraph (i) of this AD. Repairs must be done before further flight.
(1) Where Paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1318, dated October 31, 2011, specifies a compliance time after the original issue date of Boeing Alert Service Bulletin 737-53A1318, dated October 31, 2011, this AD requires compliance within the specified compliance time after the effective date of this AD.
(2) For airplanes identified as Group 1 airplanes as specified in Boeing Alert Service Bulletin 737-53A1318, dated October 31, 2011: If any cracking or sign of corrosion is found during any inspection required by this AD, and Boeing Alert Service Bulletin 737-53A1318, dated October 31, 2011, specifies to contact Boeing for appropriate action, before further flight, repair the crack or sign of corrosion using a method approved in accordance with the procedures specified in paragraph (i) of this AD.
