The U.S. Federal Aviation Administration (FAA) said on Thursday it was urging aircraft manufacturer Boeing to conduct targeted inspections of its 737 MAX aircraft to identify and address possible loose bolts in the rudder control system. Boeing shares fell 1.4% during U.S. trading on Thursday.
The FAA noted that it is closely monitoring the inspection results of the Boeing 737 MAX and will consider additional actions based on further findings of loose or missing hardware.
It is reported that before Boeing recommended the above inspection, an international operator discovered that a bolt was missing a corresponding nut during routine maintenance on the rudder control linkage mechanism. Later, Boeing discovered that in another undelivered aircraft, one of the nuts was not tightened.
In response, Boeing responded: "Repairs have been made to the aircraft where the problem was found. However, out of an abundance of caution, we recommend that operators inspect their 737 MAX aircraft and notify us of any safety concerns. We have notified the FAA and our customers and will continue to keep them informed of relevant developments."
Boeing recommended that airlines comprehensively inspect their MAX aircraft within two weeks, but the company also stated that the delivered 737 MAX aircraft can continue to fly safely and the production and delivery of MAX series aircraft will continue.
United Airlines said it did not expect the inspections to have any impact on operations; Southwest Airlines and American Airlines, the other two largest customers of MAX aircraft, have not yet responded.
United also said Boeing has urged operators of new single-aisle planes to check the specific levers that control rudder movement for possible loose hardware.
Inspection requires removing a cover and confirming that the hardware is installed correctly. This process takes about two hours, and Boeing is fully inspecting the undelivered 737 MAX aircraft before delivering them to customers.
Boeing noted that any issues involving the rudder not functioning properly could have been discovered during preflight inspections, as crews routinely check the rudder system before takeoff.
Anthony Brickhouse, an aviation safety expert at Embry-Riddle Aeronautical University, said the inspections will help the FAA determine how widespread the problem is and whether it indicates a larger lapse in Boeing production quality that requires further action by regulators.
In 2018 and 2019, two fatal accidents occurred in Indonesia and Ethiopia, killing 346 people. This major accident in the history of civil aviation has seriously affected public confidence in Boeing. Since then, the 737MAX has been grounded around the world for 20 months. Currently, Boeing is still waiting for the certification of the smaller 737MAX7 and the larger MAX10.