AD 2021-24-12 Airworthiness Directives; The Boeing Company Airplanes

Models named: 777-200, -200LR, -300, -300ER, 777F series. Read the applicability below — it usually turns on serial or part numbers too.

This AD applies to The Boeing Company Model 777-200, -200LR, -300, -300ER, and 777F series airplanes, certificated in any category, having line numbers (L/Ns) 1 through 1609 inclusive.

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 in Section D, “Airworthiness Limitations—Systems,” including Subsections D.1, D.2, and D.3, of Section 9, Airworthiness Limitations (AWLs) and Certification Maintenance Requirements (CMRs), D622W001-9, dated November 2019, of Boeing 777-200/200LR/300/300ER/777F Maintenance Planning Data (MPD) Document; or Section D, “Airworthiness Limitations—Systems,” including Subsections D.1, D.2, and D.3, of Section 9, Airworthiness Limitations (AWLs) and Certification Maintenance Requirements (CMRs), D622W001-9, dated February 2021, of Boeing 777-200/200LR/300/300ER/777F Maintenance Planning Data (MPD) Document; except as provided by paragraph (h) and (i) of this AD. The initial compliance time for doing the airworthiness limitation instructions (ALI) tasks is at the times specified in paragraphs (g)(1) through (10) of this AD. (1) For AWL 28-AWL-01, “External Wires Over Center Fuel Tank”: Within 16,000 flight cycles or 3,000 days, whichever occurs first after the date of issuance of the original airworthiness certificate or the date of issuance of the original export certificate of airworthiness; or within 16,000 flight cycles or 3,000 days, whichever occurs first after the most recent inspection was performed as specified in AWL 28-AWL-01; whichever occurs later. (2) For AWL 28-AWL-03, “Fuel Quantity Indicating System (FQIS)—Out of Tank Wiring Lightning Shield to Ground Termination”: Within 16,000 flight cycles or 3,000 days, whichever occurs first after the date of issuance of the original airworthiness certificate or the date of issuance of the original export certificate of airworthiness; or within 16,000 flight cycles or 3,000 days, whichever occurs first after the most recent inspection was performed as specified in AWL 28-AWL-03; whichever occurs later. (3) For AWL 28-AWL-18, “Over-Current and Arcing Protection Electrical Design Features Operation—AC Fuel Pump GFI and GFP”: Within 375 days after the date of issuance of the original airworthiness certificate or the date of issuance of the original export certificate of airworthiness; or within 375 days after accomplishment of the actions specified in Boeing Service Bulletin 777-28A0037; or within 375 days after accomplishment of the actions specified in Boeing Service Bulletin 777-28A0038; or within 375 days after the most recent inspection was performed as specified in AWL 28-AWL-18; whichever occurs latest. (4) For AWL 28-AWL-21, “External Wires Over Auxiliary Fuel Tank (Cell)”: Within 16,000 flight cycles or 3,000 days, whichever occurs first after the date of issuance of the original airworthiness certificate or date of issuance of the original export certificate of airworthiness; or within 16,000 flight cycles or 3,000 days, whichever occurs first after the most recent inspection was performed as specified in AWL 28-AWL-21; or within 365 days after the effective date of this AD; whichever occurs latest. (5) For AWL 28-AWL-26, “Auxiliary Fuel Tank (Cell) AC Fuel Pump Uncommanded ON/Automatic Shutoff Circuit”: Within 375 days after the date of issuance of the original airworthiness certificate or the date of issuance of the original export certificate of airworthiness; or within 375 days after the most recent inspection was performed as specified in AWL 28-AWL-26; or within 30 days after the effective date of this AD; whichever occurs latest. (6) For AWL 28-AWL-32, “Cushion Clamps and Teflon Sleeving Installed on Out-of-Tank Wire Bundles Installed on Brackets that are Mounted Directly on the Fuel Tanks”: For airplanes having L/Ns 1 through 503 inclusive, within 3,750 days after accomplishment of the actions specified in Boeing Service Bulletins 777-57A0050, or within 60 months after the effective date of this AD, whichever occurs later. For airplanes having L/Ns 504 and subsequent, within 3,750 days after the date of issuance of the original airworthiness certificate or the date of issuance of the original export certificate of airworthiness; or within 60 months after the effective date of this AD; whichever occurs later. (7) For AWL 28-AWL-101, “Engine Fuel Suction Feed Operational Test”: Within 7,500 flight hours after the date of issuance of the original airworthiness certificate or the date of issuance of the original export certificate of airworthiness; or within 7,500 flight hours after the most recent inspection was performed as specified in AWL 28-AWL-101; whichever occurs later. (8) For AWL 47-AWL-04, “NGS—Thermal Switch”: Within 108,000 flight hours after the date of issuance of the original airworthiness certificate or the date of issuance of the original export certificate of airworthiness; or within 108,000 flight hours after accomplishment of the actions specified in Boeing Service Bulletin 777-47-0002; or within 108,000 flight hours after the most recent inspection was performed as specified in AWL 47-AWL-04; whichever occurs latest. (9) For AWL 47-AWL-05, “NGS—Cross Vent Check Valve”: Within 10,682 flight hours after the date of issuance of the original airworthiness certificate or the date of issuance of the original export certificate of airworthiness; or within 10,682 flight hours after accomplishment of the actions specified in Boeing Service Bulletin 777-47-0002; or within 10,682 flight hours after the most recent inspection was performed as specified in AWL 47-AWL-05; whichever occurs latest. (10) For AWL 47-AWL-06, “NGS—NEA Distribution Ducting Integrity”: Within 10,682 flight hours after the date of issuance of the original airworthiness certificate or the date of issuance of the original export certificate of airworthiness; or within 10,682 flight hours after accomplishment of the actions specified in Boeing Service Bulletin 777-47-0002; or within 10,682 flight hours after the most recent inspection was performed as specified in AWL 47-AWL-06; whichever occurs latest.

This AD was prompted by significant changes, including new or more restrictive requirements, made to the airworthiness limitations (AWLs) and Critical Design Configuration Control Limitations (CDCCLs) related to fuel tank ignition prevention, the engine fuel suction feed system, and the nitrogen generation system. The FAA is issuing this AD to address ignition sources inside the fuel tanks and the increased flammability exposure of the center fuel tank caused by latent failures, alterations, repairs, or maintenance actions, which could result in a fuel tank explosion and consequent loss of an airplane; and to address potential loss of engine fuel suction feed capability, which could result in dual engine flameouts, inability to restart engines, and consequent forced landing of the airplane.

This AD affects the ADs specified in paragraphs (b)(1) and (2) of this AD. (1) AD 2008-11-13, Amendment 39-15536 (73 FR 30737, May 29, 2008) (AD 2008-11-13). (2) AD 2014-09-09, Amendment 39-17844 (79 FR 30005, May 27, 2014) (AD 2014-09-09).