Boeing is urging airlines to inspect its 737 Max airplanes for a possible loose bolt in rudder control systems. The airplane maker called for the inspections after an international operator discovered a bolt with a missing nut, the Federal Aviation Administration (FAA) said. An airplane's rudder is used to control the aircraft while in flight. "The issue identified on the particular airplane has been remedied," Boeing said. "Out of an abundance of caution, we are recommending operators inspect their 737 Max airplanes and inform us of any findings. "We informed the FAA and our customers and will continue to keep them aware of the progress." The FAA said it was "closely monitoring targeted inspections of Boeing 737 Max airplanes to look for a possible loose bolt in the rudder control system". Boeing has recommended that the checks — which take only about two hours — happen within the next two weeks. Any problems involving a faulty rudder would likely be identified in a pre-flight check, as crews routinely examine the rudder system before flying, Boeing said. Anthony Brickhouse, an air safety expert at the Embry-Riddle Aeronautical University, said that airlines "need to take it seriously". "But as a member of the flying public, I don't see this as an issue to be concerned about," he told Reuters news agency. Boeing's 737 Max was cleared to fly passengers again by US regulators in 2020 having been grounded for 20 months worldwide after two catastrophic accidents killed 346 people in Ethiopia and Indonesia. — BBC