The Federal Aviation Administration (FAA) said it was closely monitoring the situation and is considering further action, which could include an Airworthiness Directive (AD) for the issue forcing airlines to carry out checks.
It was an “international operator” who found the loose bolt which had completely lost its securing nut on a mechanism in the rudder-control linkage.
A spokesperson for 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.”
Boeing recommends operators check the parts in question within two weeks but confirmed production and delivery of the 737 Max range will continue as normal.
The FAA said it would “remain in contact with Boeing and the airlines while the inspections are underway”.
Boeing’s 737 Max range has had its fair share of problems since launch but remains popular with airlines. The type was grounded for almost two years shortly after launch following two fatal crashes attributed to a flaw in the aircraft’s computer systems.
As a result, the model is still heavily scrutinised by the FAA which tracks all 737 Max airlines in operation daily using satellite technology.