Airworthiness Directive · Amendment 39-18715 · Fuselage
The Boeing Company Airplanes
This AD applies to all the Boeing Company Model 737-400 series airplanes, certificated in any category.
We are adopting a new airworthiness directive (AD) for all The Boeing Company Model 737-400 series airplanes. This AD was prompted by reports of cracks in the upper chord of the overwing stub beams at body station (STA) 578 emanating from the rivet location common to the crease beam inner chord and the overwing stub beam upper chord. This AD requires repetitive inspections for cracking, and related investigative and corrective actions if necessary. We are issuing this AD to prevent the unsafe condition on these products.
At the applicable time specified in table 1 in paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1347, Original Issue, dated December 9, 2015 (“ASB 737-53A1347 Original Issue”), except as required by paragraphs (j)(1) and (j)(2) of this AD: Do a surface high frequency eddy current (HFEC) inspection for any cracking in the overwing stub beam upper chord at STA 559, STA 578, and STA 601; and do all applicable related investigative and corrective actions; in accordance with the Accomplishment Instructions of ASB 737-53A1347 Original Issue, except as specified in paragraph (j)(3) of this AD. Do all applicable related investigative and corrective actions before further flight. Repeat the HFEC inspection thereafter at the applicable intervals specified in ASB 737-53A1347 Original Issue.
Note 1 to paragraph (g) of this AD: Deviation from the actions specified in ASB 737-53A1347 Original Issue may affect compliance with the fuel tank ignition prevention requirements specified in Critical Design Configuration Control Limitation 28-AWL-11 of Document D6-38278-CMR.
Replacement of the overwing stub beam, in accordance with Part 4 of the Accomplishment Instructions of ASB 737-53A1347 Original Issue, terminates the repetitive inspections required by paragraph (g) of this AD at the STA 578 replacement location only. The post-replacement inspections required by paragraph (i) of this AD are still required at the STA 578 replacement location.
For airplanes on which an overwing stub beam has been replaced at STA 578, in accordance with Part 4 of the Accomplishment Instructions of ASB 737-53A1347 Original Issue: At the applicable time specified in table 2 in paragraph 1.E., “Compliance,” of ASB 737-53A1347 Original Issue, do a surface HFEC inspection for any cracking in the overwing stub beam upper chord at STA 578, in accordance with the Accomplishment Instructions of ASB 737-53A1347 Original Issue. Repeat the HFEC inspection thereafter at the applicable intervals specified in ASB 737-53A1347 Original Issue. If any cracking is found during any inspection required by this paragraph, before further flight, repair the cracking using a method approved in accordance with the procedures specified in paragraph (j)(3) of this AD.
(1) Where ASB 737-53A1347 Original Issue, 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.
(2) The Condition column of paragraph 1.E., “Compliance,” of ASB 737-53A1347 Original Issue, refers to airplanes with specified total flight-cycles “at the original issue date of this service bulletin.” This AD, however, applies to the airplanes with the specified total flight-cycles as of the effective date of this AD.
(3) If any cracking is found during any inspection required by this AD, and ASB 737-53A1347 Original Issue specifies to contact Boeing for appropriate action: Before further flight, repair the cracking or replace the stub beam, using a method approved in accordance with the procedures specified in paragraph (l) of this AD.
This AD does not require the “Recommended Economic Inspection” specified in paragraph 3.B.3. of the Accomplishment Instructions of ASB 737-53A1347 Original Issue.
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
Aircraft
