A quality control lapse at Boeing discovered in December has proved less significant than it at first appeared.
Airlines worldwide have inspected the rudders on the more than 1,400 Boeing 737 MAX aircraft in service globally for loose bolts and found no faults.
After an international airline discovered a rudder bolt with a missing nut while performing routine maintenance in December, Boeing inspected the MAXs it had under assembly and found one other instance of a loose rudder bolt on an undelivered jet.
Though the fault was not considered an immediate safety concern, on Dec. 27 Boeing then recommended the inspections of the entire fleet.
The rudder is a movable flap on the rear edge of the jet’s vertical tailfin that is moved to steer the plane left or right.
The inspections required mechanics to remove an access panel and visually confirm that the bolt in the rudder-control system had been properly installed.
On Thursday, the FAA issued an Airworthiness Directive, formally mandating those inspections for all MAX aircraft. However, with all the inspections completed, the directive is essentially redundant.
“All U.S. airlines completed the inspections in early January,” the safety agency said. “The FAA carefully reviewed the inspection results, which found no missing or loose rudder bolts.”
Boeing in a statement said that the more than 1,400 MAXs flying worldwide have all been inspected and nothing amiss was found.
“To date, no other airplane has been found with the condition that initiated the inspection,” Boeing said. “Operators who completed the inspection do not have to perform additional examinations and can continue safely flying their airplanes.”
Boeing added that there is one MAX operated by a foreign airline that is not in service at the moment and it will be inspected before it returns to flying.
The rudder bolt issue got attention because it followed two more serious quality lapses last year.
In April, fittings at two of eight points where the vertical fin is attached to the fuselage were found to have been improperly installed. Repairing this caused MAX delivery delays for a couple of months.
In August, Boeing discovered improperly drilled holes in the aft pressure bulkhead, the dome-shaped metal cap at the rear of the passenger cabin.
As for the previous quality lapse, Boeing said this was “not an immediate safety-of-flight issue.” Still, it had to be repaired and again MAX deliveries were delayed for a couple of months.
The Alaska Airlines Flight 1282 midair blowout revealed a quality lapse that was certainly an immediate safety-of-flight issue, bringing intense scrutiny to the frequency of quality control failures.
In the litany of prior faults, though, the loose rudder bolts lapse has now proved minor.
