On Thursday, the Federal Aviation Administration (FAA) officially required inspections of Boeing 737 MAX airplanes to check for loose bolts in the rudder control systems, following Boeing's recommendation in December. The FAA confirmed that all U.S. airlines had carried out these inspections by early January, finding no missing or loose rudder bolts. This inspection requirement, issued on Thursday, meets U.S. international obligations for ongoing operational safety. The matter of bolts and Boeing planes has become more important since the National Transportation Safety Board (NTSB) published its initial report this week on a mid-air emergency involving an Alaska Airlines Boeing 737 MAX 9 on January 5, which lost a cabin panel at an altitude of 16,000 feet. The NTSB stated that the door panel appeared to be missing four crucial bolts.
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The NTSB explained that the panel, known as a door plug, which was installed in this MAX 9 model instead of an optional exit, could have become detached from the aircraft. In December, after an international operator found a rudder bolt missing a nut during routine maintenance, and Boeing found another undelivered aircraft with a nut that wasn't properly tightened, Boeing recommended the loose-bolt inspections.
Boeing announced on Thursday that since it suggested the inspections in late December, operators have examined over 1,400 737 MAX airplanes, with only one inspection left. Boeing stated, "So far, no other aircraft has been discovered with the condition that triggered the inspection. Operators who have completed the inspection do not need to conduct further checks and can continue to safely operate their aircraft." Maria Cantwell, Chair of the Senate Commerce Committee, informed reporters on Thursday that the NTSB had told her this week that markings on the recovered 737 MAX 9 door plug indicated that the door plug had moved on previous flights. Cantwell questioned, "Why wasn't this detected earlier?"
Both Alaska and United Airlines reported last month that they had discovered loose bolts on several airplanes during inspections of MAX 9 jets. On January 6, the FAA grounded 171 MAX 9 jets and then lifted the grounding on January 24 after it required thorough inspections of the door plugs. The FAA also prohibited Boeing from increasing the current 737 MAX production rate until quality control improvements are made.