Airworthiness Directive · Amendment 39-18220 · Fuselage
The Boeing Company Airplanes
This AD applies to The Boeing Company Model 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-400F, 747SR, and 747SP series airplanes; certificated in any category, as identified in Boeing Alert Service Bulletin 747-53A2861, dated April 1, 2014.
We are adopting a new airworthiness directive (AD) for certain The Boeing Company Model 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-400F, 747SR, and 747SP series airplanes. This AD was prompted by reports of skin cracks and subsequent findings of hidden corrosion found on the mating surfaces between certain skin and stringers at circumferential skin splices. This AD requires general visual inspections of the fuselage skin at certain lower circumferential splices for the presence of existing external doublers, repetitive inspections of the fuselage skin, and related investigative and corrective actions if necessary. We are issuing this AD to detect and correct hidden corrosion due to compromised fillet seals, which can result in skin cracking and consequent loss of capability to support limit loads.
For airplanes identified as Group 1 in Boeing Alert Service Bulletin 747-53A2861, dated April 1, 2014: At the applicable times specified in paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 747-53A2861, dated April 1, 2014, except as provided by paragraph (i)(1) of this AD, do external general visual inspections for the presence of external doublers on the fuselage skin, and do the applicable actions specified in paragraphs (g)(1) and (g)(2) of this AD, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2861, dated April 1, 2014, except as required by paragraphs (i)(2), (i)(3), and (i)(4) of this AD. Do all applicable repetitive inspections of the fuselage skin thereafter at the applicable times specified in paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 747-53A2861, dated April 1, 2014.
(1) For each affected area with an external repair doubler: Before further flight, do a surface low frequency eddy current (LFEC) inspection for skin cracks of the external lower lobe repair doubler, and do all applicable related investigative and corrective actions. Do all applicable related investigative and corrective actions before further flight.
(2) For any affected area with no external repair doubler: Before further flight, do a surface LFEC inspection for corrosion of the external lower lobe skin surface, and do all applicable related investigative and corrective actions. Do all applicable related investigative and corrective actions before further flight.
For airplanes identified as Group 2 in Boeing Alert Service Bulletin 747-53A2861, dated April 1, 2014: At the applicable times specified in paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 747-53A2861, dated April 1, 2014, except as provided by paragraph (i)(1) of this AD, do external general visual inspections for the presence of external doublers on the fuselage skin, and do the applicable actions specified in paragraphs (h)(1) and (h)(2) of this AD, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2861, dated April 1, 2014, except as required by paragraphs (i)(2), (i)(3), and (i)(4) of this AD.
(1) For affected areas with any existing repair doubler: Before further flight, do inspections and applicable repairs using a method approved in accordance with the procedures specified by paragraph (j) of this AD.
(2) For affected areas with no existing repair doubler, do the applicable actions specified in paragraph (h)(2)(i) and (h)(2)(ii) of this AD.
(i) Before further flight, do a surface LFEC inspection for corrosion of the external lower lobe doubler, a surface LFEC inspection for skin cracks of the external lower lobe doubler, a detailed inspection for cracks of the external lower lobe skin, and do all applicable related investigative and corrective actions. Do all applicable related investigative and corrective actions before further flight.
(ii) Do all applicable repetitive inspections of the fuselage skin thereafter at the applicable times specified in paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 747-53A2861, dated April 1, 2014.
(1) Where Boeing Alert Service Bulletin 747-53A2861, dated April 1, 2014, 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) Although Boeing Alert Service Bulletin 747-53A2861, dated April 1, 2014, specifies to contact Boeing for repair data, 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 (j) of this AD.
(3) Where Paragraph 3.B, Part 2, Step 1, of the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2861, dated April 1, 2014, incorrectly identifies “747 NDT Manual Part 6, 51-00-00, Procedure 8,” associated with the LFEC inspection for skin cracks of the external lower lobe repair doubler, the correct reference is “747 NDT Manual Part 6, 53-30-00, Procedure 5.”
(4) Where Paragraph 3.B, Part 3, Step 1, of the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2861, dated April 1, 2014, specifies doing external surface LFEC inspections in accordance with “747 NDT Manual Part 6, 51-00-00, Procedure 5 or Procedure 12,” and the skin panels are chem milled with a thickness that exceeds the specification listed in Table 2 of Appendix C of Boeing Alert Service Bulletin 747-53A2861, dated April 1, 2014, this AD requires using a method approved in accordance with the procedures specified in paragraph (j) of this AD.
