Millions of people travel on commercial airliners daily. When doing so, airline passengers primarily place their safety in the airlines, the aircraft manufacturers, and the aircraft they fly on. The last thing someone wants to hear about when flying is a potential issue with the plane they will be flying on. American aerospace company Boeing is scrambling to warn airlines to inspect their Boeing 737 MAX aircraft following the potential of a loose bolt in its rudder system. 

A Rocky Start to the New Year

In late December 2023, mechanics at Boeing found a loose bolt inside a soon-to-be-delivered 737 MAX aircraft. This potential issue plaguing new 737 MAX aircraft centers around the specific tie rods that control the rudder's movement in the 737 MAX aircraft type. According to U.S.-based Boeing, the company has urged airlines operating new 737 MAX aircraft to perform "safety checks" on their new planes to determine if the loose bolts are a widespread issue or a rare one-off occurrence due to a quality defect.  

According to the FAA, the issue was first spotted "...after an international operator discovered a bolt with a missing nut while performing routine maintenance...in the rudder-control linkage..." Shortly after, Boeing mechanics discovered the issue on an undelivered aircraft. In India, the alert has elicited Indian airlines that operate the 737 MAX and its variants to inspect their aircraft. A report by Indian news outlet NDTV has stated that the Indian aviation regulatory body, DGCA (Directorate General for Civil Aviation), will contact Indian airlines as they perform their safety checks. 

Numerous carriers in the United States operate and have the Boeing 737 MAX on order, including American Airlines, United, Alaska Airlines, and, most notably, Southwest Airlines. The Dallas, Texas-based airline currently operates a fleet of all Boeing aircraft, with dozens of 737 MAX aircraft on order. Should loose bolts become a widespread problem, this could mean more operating delays and flight cancellations for Southwest, which was already having trouble with its aircraft fleet and aircrews due to weather, and delays on 737 MAX orders. 

So Why Is This an Issue? 

The rudder is a control surface vital to the directional turning of a plane. It is located on the back of an aircraft, typically on the back tail of the plane. Pilots control their plane's rudder using pedals in the cockpit, which, when pushed one way or the other, will pivot the aircraft towards the left or the right, without raising the wings. When combined with ailerons on the wing (controlled by pushing the control stick left or right), the rudder and ailerons make planes turn left or right - a vital function. This is why a potential loose bolt can be such a significant issue to flight crew and passenger safety. 

Previous Issues With the Boeing 737 MAX. 

In 2019, numerous national aviation regulators, including the Chinese CAAC and American FAA, grounded all 737 MAX aircraft in light of two fatal crashes involving the type after the aircraft's MCAS pitch correction system malfunctioned twice. After fixing the issue with the MCAS system and undergoing vigorous inspections of their aircraft and facilities, aviation regulators cleared the 737 MAX to fly again in 2021. 

Boeing has also experienced issues with the building of planes in the company's 787 fleet, as the New York Times reported in June 2019, "...detailed allegations of shoddy work and flawed quality control at the factory that threatened to compromise safety..."

The next few months will prove whether or not loose bolts will be the next big issue with Boeing's planes.