Airworthiness Directive · Amendment 39-22049 · Fuel
The Boeing Company Airplanes
This AD applies to The Boeing Company Model 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747SP, 747-400, 747-400D, and 747-400F series airplanes, certificated in any category, having line numbers 645 and subsequent.
The FAA is adopting a new airworthiness directive (AD) for certain The Boeing Company Model 747-100B SUD, 747-200B, 747-200C, 747- 200F, 747-300, 747SP, 747-400, 747-400D, and 747-400F series airplanes. This AD was prompted by a determination that a certain fastener type that penetrates the fuel tank walls has insufficient bond to the structure, and energy from a lightning strike or high-powered short circuit could cause arcing to occur at the ends of fasteners in the fuel tanks. This AD requires, for certain airplanes, reconfiguring the clamps of certain wire bundles, applying sealant to certain fasteners that penetrate the fuel tank walls, installing cushion clamps and polytetrafluoroethylene (TFE) sleeves, inspecting to determine if sealant was applied to certain fasteners, and applying sealant if necessary. This AD also requires, for all airplanes, revising the maintenance or inspection program, as applicable, to incorporate new, more restrictive airworthiness limitations (AWLs). The FAA is issuing this AD to address the unsafe condition on these products.
(1) For Group 1 through 9, 11, and 16 through 45 airplanes identified in Boeing Special Attention Service Bulletin 747-57-2327, Revision 8, dated November 13, 2020: Within 60 months after the effective date of this AD, reconfigure the clamps of the specified wire bundles, apply sealant to the specified fasteners that penetrate the fuel tank walls, and install cushion clamps and polytetrafluoroethylene (TFE) sleeves on the wire bundles of the front spars and rear spars of the wings, as applicable, in accordance with Work Packages 13 through 21, as applicable, of the Accomplishment Instructions of Boeing Special Attention Service Bulletin 747-57-2327, Revision 8, dated November 13, 2020.
(2) For airplanes on which the actions specified in Work Package 7, 8, or 9 of Boeing Special Attention Service Bulletin 747-57-2327 have been done: Within 60 months after the effective date of this AD, inspect to determine if the fillet sealant identified in step 5 of Figure 23 of Boeing Special Attention Service Bulletin 747-57-2327, Revision 8, dated November 13, 2020, was applied to fully encapsulate the fastener penetrating the fuel tank; and if the sealant does not fully encapsulate the fastener, before further flight, apply sealant as specified in step 5 of Figure 23, except where note (f) of Figure 23 specifies to “make sure to apply the fillet sealant on the fastener,” this AD requires applying the fillet sealant to fully encapsulate the fastener penetrating the fuel tank.
(3) For Group 2 airplanes identified in Boeing Special Attention Service Bulletin 747-57-2326, Revision 1, dated January 31, 2008, on which fasteners were sealed using Boeing Special Attention Service Bulletin 747-57-2326, dated January 4, 2007: Within 60 months after the effective date of this AD, inspect to determine if all fasteners identified in Figures 4 and 5 of Boeing Special Attention Service Bulletin 747-57-2326, Revision 1, dated January 31, 2008, have been sealed; and if any fasteners are not sealed, before further flight, apply sealant in accordance with Figure 1 of Boeing Special Attention Service Bulletin 747-57-2326, Revision 1, dated January 31, 2008.
(1) For Model 747-400, 747-400D, and 747-400F series airplanes: Within 60 days after the effective date of this AD: Revise the existing maintenance or inspection program, as applicable, by incorporating the information in airworthiness limitations (AWLs) 28-AWL-33, 28-AWL-34, and 28-AWL-37 of The Boeing Company 747-400 Maintenance Planning Data (MPD) Document, Section 9, Airworthiness Limitations (AWLs) and Certification Maintenance Requirements (CMRs), D621U400-9, Revision February 2020. The initial compliance time for doing AWL No. 28-AWL-33, “Cushion Clamps and Teflon Sleeving Installed on Out-of-Tank Wire Bundles Installed on Brackets that are Mounted Directly on the Fuel Tanks,” is at the applicable time specified in paragraphs (h)(1)(i) or (ii) of this AD.
(i) For airplanes that did not have any version of AWL No. 28-AWL-33 in the existing maintenance or inspection program before the effective date of this AD: Within 144 months since issuance of the original airworthiness certificate or original export certificate of airworthiness, within 144 months since Boeing Special Attention Bulletin 747-57-2327 was incorporated, or within 12 months after the effective date of this AD, whichever occurs latest.
(ii) For airplanes not identified in paragraph (h)(1)(i) of this AD: Within 144 months since AWL No. 28-AWL-33 was incorporated into the existing maintenance or inspection program, or within 144 months after the most recent inspection was performed as specified in AWL No. 28-AWL-33, whichever occurs later.
(2) For Model 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, and 747SP series airplanes: Within 60 days after the effective date of this AD, revise the existing maintenance or inspection program, as applicable, by incorporating the information in AWLs 28-AWL-25, 28-AWL-27, and 28-AWL-28 of The Boeing Company 747-100/200/300/SP/SR Airworthiness Limitations (AWLs) and Certification Maintenance Requirements (CMRs), D6-13747-CMR, Revision September 2020; except where the “Applicability” of AWLs 28-AWL-25 and 28-AWL-27 specifies “ALL” and “NOTE,” replace “ALL” and “NOTE” with “Airplanes L/N 645 and on” and remove the “Applicability Note” from the Description column of 28-AWL-25 and 28-AWL-27. The initial compliance time for doing AWL No. 28 AWL-25, “Cushion Clamps and Teflon Sleeving Installed on Out-of-Tank Wire Bundles Installed on Brackets that are Mounted Directly on the Fuel Tanks,” is at the applicable time specified in paragraphs (h)(2)(i) or (ii) of this AD.
(i) For airplanes that did not have any version of AWL No. 28-AWL-25 in the existing maintenance or inspection program before the effective date of this AD: Within 144 months since issuance of the original airworthiness certificate or original export certificate of airworthiness, within 144 months since Boeing Special Attention Bulletin 747-57-2327 was incorporated, or within 12 months after the effective date of this AD, whichever occurs latest.
(ii) For airplanes not identified in paragraph (h)(2)(i) of this AD: Within 144 months since AWL No. 28-AWL-25 was incorporated into the maintenance or inspection program, or within 144 months after the most recent inspection was performed as specified in AWL No. 28-AWL-25, whichever occurs later.
After the maintenance or inspection program has been revised as required by paragraph (h)(1) or (2) of this AD, no alternative actions (e.g., inspections), intervals, and CDCCLs may be used unless the actions, intervals, and CDCCLs are approved as an alternative method of compliance (AMOC) in accordance with the procedures specified in paragraph (k) of this AD.
