Airworthiness Directive · Amendment 39-18895 · Fuselage
The Boeing Company Airplanes
(1) This AD applies to The Boeing Company Model 737-300, -400, and -500 series airplanes, certificated in any category, as identified in Boeing Alert Service Bulletin 737-53A1343, dated March 25, 2016; except for Group 5 airplanes identified in Boeing Alert Service Bulletin 737-53A1343, dated March 25, 2016.
(2) Installation of Supplemental Type Certificate (STC) ST01219SE (http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgstc.nsf/0/EBD1CEC7B301293E86257CB30045557A?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 adopting a new airworthiness directive (AD) for certain The Boeing Company Model 737-300, -400, and -500 series airplanes. This AD was prompted by an evaluation by the design approval holder (DAH) indicating that the fuselage skin is subject to widespread fatigue damage (WFD). This AD requires modification of the lap joint and repetitive inspections for cracking of the skin at critical fastener rows. We are issuing this AD to address the unsafe condition on these products.
Before the accumulation of 50,000 total flight cycles, or within 3,000 flight cycles after the effective date of this AD, whichever occurs later: Modify the lap joint skin, including doing all applicable related investigative and corrective actions, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1343, dated March 25, 2016, except as required by paragraph (i) of this AD. Do all applicable related investigative and corrective actions before further flight.
Within 38,000 flight cycles after modifying the lap joint skin as required by paragraph (g) of this AD: Inspect the skin at critical fastener rows by doing the actions specified in paragraph (h)(1) or (h)(2) of this AD, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1343, dated March 25, 2016. If any crack is found during any inspection, repair before further flight using a method approved in accordance with the procedures specified in paragraph (l) of this AD. Repeat the inspection thereafter at intervals not to exceed 2,000 flight cycles in unrepaired areas.
(1) From the inside of the airplane: Do a low frequency eddy current (LFEC) inspection for any crack in the skin at the critical fastener row, and a medium frequency eddy current (MFEC) inspection for any crack in the skin at the critical fastener row.
(2) From the outside of the airplane: Do a LFEC inspection for any crack in the fuselage skin.
Although Boeing Alert Service Bulletin 737-53A1343, dated March 25, 2016, specifies to contact Boeing for repair instructions, and specifies that action as “RC” (Required for Compliance), this AD requires repair before further flight using a method approved in accordance with the procedures specified in paragraph (l) of this AD.
Table 5 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1343, dated March 25, 2016, specifies post-modification airworthiness limitation inspections in compliance with 14 CFR 25.571(a)(3) at the modified locations, which support compliance with 14 CFR 121.1109(c)(2) or 129.109(b)(2). As airworthiness limitations, these inspections are required by maintenance and operational rules. It is therefore unnecessary to mandate them in this AD. Deviations from these inspections require FAA approval, but do not require an alternative method of compliance.
Accomplishing the modification required by paragraph (g) of this AD terminates the inspections required by paragraphs (g) and (h) of AD 2015-16-08 for the modified area only.
