AD 2023-03-20 Airworthiness Directives; The Boeing Company Airplanes

Models named: 747-400, -400D, -400F series. Read the applicability below — it usually turns on serial or part numbers too.

This AD applies to all The Boeing Company Model 747-400, -400D, and -400F series airplanes, certificated in any category.

Comply with this AD within the compliance times specified, unless already done.

Within 60 days after the effective date of this AD, revise the existing maintenance or inspection program, as applicable, to incorporate the information specified in Section B, Airworthiness Limitations—Systems, of Section 9, Airworthiness Limitations (AWLs) and Certification Maintenance Requirements (CMRs), of Boeing 747-400 Maintenance Planning Data (MPD) Document, D621U400-9, dated April 2022; except as provided by paragraph (h) of this AD. The initial compliance time for doing the airworthiness limitation instruction (ALI) tasks is at the times specified in paragraphs (g)(1) through (13) of this AD. (1) For AWL No. 28-AWL-01, “External Wires Over Center Fuel Tank”: At the applicable time specified in paragraph (g)(1)(i) or (ii) of this AD. (i) For airplanes that did not have any version of AWL No. 28-AWL-01 in their 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, or within 12 months after the effective date of this AD, whichever occurs later. (ii) For airplanes not identified in paragraph (g)(1)(i) of this AD: Within 144 months since AWL No. 28-AWL-01 was added to the maintenance or inspection program, or within 144 months after the most recent inspection was performed as specified in AWL No. 28-AWL-01, whichever occurs later. (2) For AWL No. 28-AWL-03, “Fuel Quantity Indication System (FQIS)—Out of Tank Wiring Lightning Shield to Ground Termination”: At the applicable time specified in paragraph (g)(2)(i) or (ii) of this AD. (i) For airplanes that did not have any version of AWL No. 28-AWL-03 in their 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, or within 12 months after the effective date of this AD, whichever occurs later. (ii) For airplanes not identified in paragraph (g)(2)(i) of this AD: Within 144 months since AWL No. 28-AWL-03 was added to the maintenance or inspection program, or within 144 months after the most recent inspection was performed as specified in AWL No. 28-AWL-03, whichever occurs later. (3) For AWL No. 28-AWL-10, “Main Tank, Center Wing Tank, and Horizontal Stabilizer Tank (if installed) Refuel Valve Installation—Fault Current Bond”: At the applicable time specified in paragraph (g)(3)(i) or (ii) of this AD. (i) For airplanes that did not have any version of AWL No. 28-AWL-10 in their 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, or within 12 months after the effective date of this AD, whichever occurs later. (ii) For airplanes not identified in paragraph (g)(3)(i) of this AD: Within 144 months since AWL No. 28-AWL-10 was added to the maintenance or inspection program, or within 144 months after the most recent inspection was performed as specified in AWL No. 28-AWL-10, whichever occurs later. (4) For AWL No. 28-AWL-17, “Over-Current and Arcing Protection Electrical Design Features Operation—Fault Current Detector (FCD) for Center Wing Tank (CWT) Pumps and Inboard Main Tank Override/Jettison (O/J) Pumps and Horizontal Stabilizer Tank (HST) Transfer Fuel Pumps”: At the applicable time specified in paragraph (g)(4)(i) or (ii) of this AD. (i) For airplanes that did not have any version of AWL No. 28-AWL-17 in their maintenance or inspection program before the effective date of this AD: Within 18 months since issuance of the original airworthiness certificate or original export certificate of airworthiness, or within 90 days after the effective date of this AD, whichever occurs later. (ii) For airplanes not identified in paragraph (g)(4)(i) of this AD: Within 18 months since AWL No. 28-AWL-17 was added to the maintenance or inspection program, or within 18 months after the most recent inspection was performed as specified in AWL No. 28-AWL-17, whichever occurs later. (5) For AWL No. 28-AWL-24, “Horizontal Stabilizer Tank (HST) Fuel Pump Automatic Shutoff Circuit (If Installed)”: At the applicable time specified in paragraph (g)(5)(i) or (ii) of this AD. (i) For airplanes that did not have any version of AWL No. 28-AWL-24 in their maintenance or inspection program before the effective date of this AD: Within 12 months since issuance of the original airworthiness certificate or original export certificate of airworthiness, or within 90 days after the effective date of this AD, whichever occurs later. (ii) For airplanes not identified in paragraph (g)(5)(i) of this AD: Within 12 months since AWL No. 28-AWL-24 was added to the maintenance or inspection program, or within 12 months after the most recent inspection was performed as specified in AWL No. 28-AWL-24, whichever occurs later. (6) For AWL No. 28-AWL-26, “Main Tank 2 and Main Tank 3 Override/Jettison Fuel Pump Uncommanded on System”: At the applicable time specified in paragraph (g)(6)(i) or (ii) of this AD. (i) For airplanes that did not have any version of AWL No. 28-AWL-26 in their maintenance or inspection program before the effective date of this AD: Within 12 months since issuance of the original airworthiness certificate or original export certificate of airworthiness, or within 90 days after the effective date of this AD, whichever occurs later. (ii) For airplanes not identified in paragraph (g)(6)(i) of this AD: Within 12 months since AWL No. 28-AWL-26 was added to the maintenance or inspection program, or within 12 months after the most recent inspection was performed as specified in AWL No. 28-AWL-26, whichever occurs later. (7) For AWL No. 28-AWL-28, “Over-Current and Arcing Protection Electrical Design Features Operation—Main Tank AC Fuel Pump Ground Fault Interrupter (GFI)”: At the applicable time specified in paragraph (g)(7)(i) or (ii) of this AD. (i) For airplanes that did not have any version of AWL No. 28-AWL-28 in their maintenance or inspection program before the effective date of this AD: Within 12 months since issuance of the original airworthiness certificate or original export certificate of airworthiness, or within 90 days after the effective date of this AD, whichever occurs later. (ii) For airplanes not identified in paragraph (g)(7)(i) of this AD: Within 12 months since AWL No. 28-AWL-28 was added to the maintenance or inspection program, or within 12 months after the most recent inspection was performed as specified in AWL No. 28-AWL-28, whichever occurs later. (8) For AWL No. 28-AWL-29, “Over-Current and Arcing Protection Electrical Design Features Operation—Center Tank Scavenge AC Fuel Pump Ground Fault Interrupter (GFI)”: At the applicable time specified in paragraph (g)(8)(i) or (ii) of this AD. (i) For airplanes that did not have any version of AWL No. 28-AWL-29 in their maintenance or inspection program before the effective date of this AD: Within 12 months since issuance of the original airworthiness certificate or original export certificate of airworthiness, or within 90 days after the effective date of this AD, whichever occurs later. (ii) For airplanes not identified in paragraph (g)(8)(i) of this AD: Within 12 months since AWL No. 28-AWL-29 was added to the maintenance or inspection program, or within 12 months after the most recent inspection was performed as specified in AWL No. 28-AWL-29, whichever occurs later. (9) For 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,” at the applicable time specified in paragraph (g)(9)(i) or (ii) of this AD. (i) For airplanes that did not have any version of AWL No. 28-AWL-33 in their 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, or within 12 months after the effective date of this AD, whichever occurs later. (ii) For airplanes not identified in paragraph (g)(9)(i) of this AD: Within 144 months since AWL No. 28-AWL-33 was added to the 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. (10) For AWL No. 28-AWL-40, “Reserve Tank Refuel Valve Installation—Lightning Protection Electrical Bond,” at the applicable time specified in paragraph (g)(10)(i) or (ii) of this AD. (i) For airplanes that did not have any version of AWL No. 28-AWL-40 in their maintenance or inspection program before the effective date of this AD: Within 72 months since issuance of the original airworthiness certificate or original export certificate of airworthiness, or within 12 months after the effective date of this AD, whichever occurs later. (ii) For airplanes not identified in paragraph (g)(10)(i) of this AD: Within 72 months since AWL No. 28-AWL-40 was added to the maintenance or inspection program, or within 72 months after the most recent inspection was performed as specified in AWL No. 28-AWL-40, whichever occurs later. (11) For AWL No. 47-AWL-07, “Nitrogen Generation System—Nitrogen Enriched Air (NEA) Distribution Ducting Inspection,” at the applicable time specified in paragraph (g)(11)(i) or (ii) of this AD. (i) For airplanes that did not have any version of AWL No. 47-AWL-07 in their maintenance or inspection program before the effective date of this AD: Within 21,250 total flight hours since issuance of the original airworthiness certificate or original export certificate of airworthiness, or within 4 months after the effective date of this AD, whichever occurs later. (ii) For airplanes not identified in paragraph (g)(11)(i) of this AD: Within 21,250 total flight hours since AWL No. 47-AWL-07 was added to the maintenance or inspection program, or within 21,250 total flight hours after the most recent inspection was performed as specified in AWL No. 47-AWL-07, whichever occurs later. (12) For AWL No. 47-AWL-08, “Nitrogen Generation System [NGS]—Cross-Vent Check Valve Functional Check,” at the applicable time specified in paragraph (g)(12)(i) or (ii) of this AD. (i) For airplanes that did not have any version of AWL No. 47-AWL-08 in their maintenance or inspection program before the effective date of this AD: Within 21,250 total flight hours since issuance of the original airworthiness certificate or original export certificate of airworthiness, or within 4 months after the effective date of this AD, whichever occurs later. (ii) For airplanes not identified in paragraph (g)(12)(i) of this AD: Within 21,250 total flight hours since AWL No. 47-AWL- 08 was added to the maintenance or inspection program, or within 21,250 total flight hours after the most recent inspection was performed as specified in AWL No. 47-AWL-08, whichever occurs later. (13) For AWL No. 47-AWL-10, “NGS—Thermal Switch,” at the applicable time specified in paragraph (g)(13)(i) or (ii) of this AD. (i) For airplanes that did not have any version of AWL No. 47-AWL-10 in their maintenance or inspection program before the effective date of this AD: Within 54,000 total flight hours since issuance of the original airworthiness certificate or original export certificate of airworthiness, or within 4 months after the effective date of this AD, whichever occurs later. (ii) For airplanes not identified in paragraph (g)(13)(i) of this AD: Within 54,000 total flight hours since AWL No. 47-AWL-10 was added to the maintenance or inspection program, or within 54,000 total flight hours after the most recent inspection was performed as specified in AWL No. 47-AWL-10, whichever occurs later.

This AD was prompted by the FAA's analysis of the fuel system reviews on Model 747-400, -400D, and -400F series airplanes conducted by the manufacturer, and by the determination that new or more restrictive airworthiness limitations are necessary. The FAA is issuing this AD to reduce the potential of ignition sources inside fuel tanks, which, in combination with flammable fuel vapors, could result in fuel tank explosions and consequent loss of the airplane.

This AD affects the ADs specified in paragraphs (b)(1) through (7) of this AD. (1) AD 2008-10-06 R1, Amendment 39-16160 (75 FR 906, January 7, 2010) (AD 2008-10-06 R1). (2) AD 2008-18-09, Amendment 39-15666 (73 FR 52911, September 12, 2008) (AD 2008-18-09). (3) AD 2010-13-12, Amendment 39-16343 (75 FR 37997, July 1, 2010) (AD 2010-13-12). (4) AD 2010-14-08, Amendment 39-16353 (75 FR 38397, July 2, 2010) (AD 2010-14-08). (5) AD 2011-06-03, Amendment 39-16627 (76 FR 15814, March 22, 2011) (AD 2011-06-03). (6) AD 2014-15-14, Amendment 39-17916 (79 FR 45324, August 5, 2014) (AD 2014-15-14). (7) AD 2016-19-03, Amendment 39-18652 (81 FR 65872, September 26, 2016) (AD 2016-19-03).