The Federal Aviation Administration released two new airworthiness directives (AD) which require the airlines of the United States to modify their Boeing 747s and Boeing 767s fuel tank monitoring systems in order to prevent the risk of ignition within the tanks.

The new directives apply for Boeing 747-400, 767-200, 767-300, 767-300F models as well as 767-400ER series jets, the FAA announced on October 6, 2020. According to the authority, the condition affects a total of 71 Boeing 747s and 261 Boeing 767s which are registered in the U.S.

“The FAA is issuing this AD to prevent ignition sources inside the center fuel tank, which, in combination with flammable fuel vapors, could result in a fuel-tank explosion and consequent loss of the airplane,” reads both directives. 

FAA released new requirements after completing its analysis of fuel-system reviews on certain Boeing series. According to the statement, Boeing has requested the FAA to withdraw the notices of proposed rulemaking. The manufacturer said that it considered the use of nitrogen-generating systems, which reduce ignition risk by pumping nitrogen into tanks to displace oxygen.

However, the FAA identified „non-compliant design areas“ in certain Boeing series system reviews.

Under the new directives, U.S. operators are required to modify fuel-quantity indicating systems within 72 months starting from November 10, 2020.