Airworthiness Directive · Amendment 39-18735 · Fuselage
The Boeing Company Airplanes
This AD applies to The Boeing Company Model 747-400, -400D, and -400F series airplanes, certificated in any category, as specified in Boeing Alert Service Bulletin 747-53A2784, Revision 2, dated August 20, 2015.
We are superseding Airworthiness Directive (AD) 2012-22-02 for certain The Boeing Company Model 747-400, -400D, and -400F series airplanes. AD 2012-22-02 required measuring the web at station (STA) 320 and, depending on findings, various inspections for cracks and missing fasteners, web and fastener replacement, and related investigative and corrective actions if necessary. This new AD requires, for certain airplanes, replacement of the web, including related investigative and corrective actions if necessary. This AD was prompted by a determination that there were no inspection or repair procedures included in AD 2012-22-02 for airplanes with a certain crown frame web thickness. We are issuing this AD to address the unsafe condition on these products.
For Group 1, Configuration 3 airplanes, identified in Boeing Alert Service Bulletin 747-53A2784, Revision 2, dated August 20, 2015: At the compliance time specified in table 1 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 747-53A2784, Revision 2, dated August 20, 2015, measure the thickness of the crown frame web at STA 320, and do all applicable related investigative and corrective actions, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2784, Revision 2, dated August 20, 2015, except as required by paragraph (l)(2) of this AD. Do all related investigative and corrective actions at the applicable times specified in tables 2 and 3 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 747-53A2784, Revision 2, dated August 20, 2015.
For Group 1, Configuration 1 airplanes, identified in Boeing Alert Service Bulletin 747-53A2784, Revision 2, dated August 20, 2015: For airplanes with a web thickness less than 0.136 inch and no repair doubler installed on the web, at the time specified in table 2 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 747-53A2784, Revision 2, dated August 20, 2015, do a detailed inspection for cracks and a general visual inspection for missing fasteners of the crown frame web at STA 320, and do all applicable related investigative and corrective actions, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2784, Revision 2, dated August 20, 2015, except as specified in paragraph (l)(2) of this AD. Do the applicable related investigative and corrective actions at the applicable times specified in paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 747-53A2784, Revision 2, dated August 20, 2015.
For Group 1, Configuration 1 airplanes, identified in Boeing Alert Service Bulletin 747-53A2784, Revision 2, dated August 20, 2015: For airplanes with a web thickness less than 0.136 inch and a repair doubler installed on the web, at the time specified in table 3 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 747-53A2784, Revision 2, dated August 20, 2015, do a detailed inspection for any crack in the upper chord and lower chord of the STA 320 crown frame, and do all applicable related investigative and corrective actions, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2784, Revision 2, dated August 20, 2015, except as specified in paragraph (l)(2) of this AD. Do the applicable related investigative and corrective actions at the applicable times specified in paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 747-53A2784, Revision 2, dated August 20, 2015.
For Group 1, Configuration 2 airplanes, identified in Boeing Alert Service Bulletin 747-53A2784, Revision 2, dated August 20, 2015: At the applicable time specified in table 5 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 747-53A2784, Revision 2, dated August 20, 2015, except as provided by paragraph (l)(1) of this AD, replace the web, including doing related investigative and corrective actions, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2784, Revision 2, dated August 20, 2015, except as required by paragraph (l)(2) of this AD. Do all applicable related investigative and corrective actions before further flight.
Following any web replacement required by this AD, at the time specified in paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 747-53A2784, Revision 2, dated August 20, 2015: Do a detailed inspection for cracks of the web, upper chord, lower chord, and lower chord splice, and do all applicable corrective actions, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2784, Revision 2, dated August 20, 2015, except as required by paragraph (l)(2) of this AD. Do all applicable corrective actions before further flight. If no crack is found, repeat the inspection thereafter at the intervals specified in paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 747-53A2784, Revision 2, dated August 20, 2015. Accomplishment of the inspections required by AD 2009-19-05, Amendment 39-16022 (74 FR 48138, September 22, 2009), terminates the requirements of this paragraph.
(1) Where Boeing Alert Service Bulletin 747-53A2784, Revision 2, dated August 20, 2015, specifies a compliance time “after the Revision 2 date of the service bulletin,” this AD requires compliance within the specified compliance time after the effective date of this AD.
(2) Where Boeing Alert Service Bulletin 747-53A2784, Revision 2, dated August 20, 2015, specifies to contact Boeing for appropriate action, accomplish applicable actions before further flight using a method approved in accordance with the procedures specified in paragraph (n) of this AD.
