US officials say 40 airlines may be using Boeing 737s with suspect rudder parts

National Transportation Safety Board says operators could be unaware of components that may pose safety risks

The US National Transportation Safety Board on Monday said more than 40 foreign operators of Boeing 737 airplanes may be using planes with rudder components that may pose safety risks.

The NTSB last week issued urgent safety recommendations about the potential for a jammed rudder control system on some Boeing 737 airplanes after a February incident involving a United flight.