The request for extra analysis proving that the Boeing 737 MAX subsystems would not be affected by recently discovered electric issues raised fresh concerns over the timing of when certain Boeing 737 MAX aircraft would be cleared out to fly.
“U.S. air safety officials have asked Boeing to supply fresh analysis and documentation showing numerous 737 MAX subsystems would not be affected by electrical grounding issues first flagged in three areas of the jet in April,” Reuters reported on May 5, 2021, adding that the recent issue injected new uncertainty over the timing of 737 MAX ungrounding.
On April 30, 2021, the US Federal Aviation Administration (FAA) issued an Airworthiness Directive (AD) requiring Boeing to address the “unsafe condition” of certain Boeing 737 MAX aircraft. The move came after Boeing addressed potential electric issues to 16 737 MAX operators earlier in April 2021.
The investigation of certain Boeing 737 MAX aircraft identified insufficient bonding of certain “metallic support panel assemblies installed in two areas of the flight deck, which affects the electrical grounding of installed equipment”.
“This AD requires modification of the electrical bonding of these assemblies to provide sufficient electrical grounding for equipment installed in the flight deck,” read the Airworthiness Directive (AD).
As per FAA estimates, Airworthiness Directive affects 71 Boeing 737 MAX aircraft in operation in the US. The fixes for the 71 aircraft would cost $154,915.
Earlier in April 2021, following Boeing briefing on certain 737 MAX aircraft electrical issues, Boeing 737 MAX operators voluntarily grounded some of their aircraft awaiting further notice from Boeing.
“Starting immediately and out of an abundance of caution, we are voluntarily and temporarily removing 16 Boeing 737 MAX aircraft from our schedule. We have been in touch with the FAA and Boeing and will continue to work closely with them to determine any additional steps that are needed to ensure these aircraft meet our rigorous safety standards and can return to service,” United Airlines spokesperson told AeroTime News on April 12, 2021.
The safety concern of a specific group of Boeing 737 MAX aircraft comes after the US Federal Aviation Administration (FAA) ungrounded the aircraft on November 18, 2021. The aircraft was previously grounded worldwide in March 2019 following two fatal crashes that together claimed 346 lives. Both the Lion Air flight JT610 in October 2018 and the Ethiopian Airlines flight ET 302 in March 2019 crashes were blamed on a MCAS system malfunction. The system, which at the time was a little-known innovation installed on all Boeing MAX planes, is activated when angle of attack (AOA) sensors indicate that the airframe is in a dangerous angle and attempts to correct it. But if the AOA signal is erroneous, the MCAS can force an airplane nose down ‒ which is what caused the downings of flights ET302 and JT610. The latest electric issue discovered on the MAX aircraft is understood to be unrelated to the MCAS system.