The Federal Aviation Administration (FAA) of the United States (US) published a final rule known as an Airworthiness Directive (AD) to address a scenario in which a fault current or lightning strike could potentially cause fuel tank explosions.
Following Boeing’s examinations of the fuel systems, the FAA published a notice of proposed rulemaking (NPRM) mandating operators of the Boeing 777 type to modify the aircraft’s fuel system.
Airlines using any model of the 777 will have to install Teflon sleeves, seal fasteners with caps, perform in-depth inspections, and implement corrective measures, according to the AD, which was published on February 28, 2023.
“This AD also requires revising the existing maintenance or inspection program, as applicable, to incorporate more restrictive airworthiness limitations (AWLs),” read the directive.
“The FAA is issuing this AD to address arcing inside the main and center fuel tanks in the event of a fault current or lightning strike, which, in combination with flammable fuel vapors, could result in a fuel tank explosion and consequent loss of the airplane,” added the FAA.
The Air Line Pilots Association (ALPA), airlines, and Boeing themselves contributed a total of eight comments to the regulator. While ALPA backed the NPRM without making any changes, other stakeholders offered input on the rule.