The head of the National Transportation Safety Board criticized aviation regulators for “downplaying the urgency” of a possible rudder malfunction on some Boeing aircraft in an unusually public rebuke.

The National Transportation Safety Board issued urgent safety recommendations to Boeing over a steering defect related to its 737 planes, adding its growing list of woes.

NTSB chair Jennifer Homendy accused the FAA of "downplaying the urgency" of potentially defective rudder systems on some Boeing 737 Max jets.

The U.S. National Transportation Safety Board on Monday said more than 40 foreign operators of Boeing (NYSE:BA) 737 planes may have rudder components that could be a safety risk. The warning came after the NTSB last week issued urgent safety recommendations about the possibility of jammed rudder control systems on some 737 airplanes.