(New York) American aircraft manufacturer Boeing has asked airlines that own its 737 MAX, its flagship plane, to carry out checks because of a risk of a “loose bolt” on the rudder control system, announced Thursday the United States Civil Aviation Agency (FAA).

The FAA said in a statement “closely monitoring targeted inspections of Boeing 737 MAX airplanes for the possibility of a loose bolt in the rudder control system.”

After discussions between this agency and the manufacturer, the latter issued a multi-operator message (MOM) so that airlines can carry out checks.

“The issue identified on a particular aircraft has been resolved. Out of an abundance of caution, we recommend that operators inspect their 737 MAX aircraft and inform us of their findings,” a spokesperson for the aircraft manufacturer said in a statement.

This inspection consists of opening an access hatch and visually observing whether everything is compliant. This process is expected to take approximately two hours by plane.

The FAA also asked airlines to report if this problem has been spotted in the past during maintenance operations.

She said Boeing acted after an international operator discovered a bolt missing its nut while conducting routine maintenance on the rudder control system mechanism.

The aircraft manufacturer then spotted a nut “which was not properly tightened” on an aircraft not yet delivered.

Around 1:40 p.m. (Eastern time), Boeing stock was down 1.17% on the New York Stock Exchange.

The 737 MAX was grounded for many months around the world after two air disasters involving the aircraft in October 2018 and March 2019, which left 346 dead.

More recently, the aircraft manufacturer had to slow down its deliveries due to problems on the fuselage, in particular on the rear watertight bulkhead of the aircraft.

Boeing has delivered a total of more than 1,370 examples of the 737 MAX and its order book currently stands at more than 4,000.