US officials have raised concerns that over 40 foreign airlines may be operating Boeing 737 aircraft equipped with potentially hazardous rudder components. The National Transportation Safety Board (NTSB) announced this information on Monday, highlighting that these operators might be unaware of the safety risks associated with these parts. The NTSB's warning follows urgent safety recommendations issued last week regarding the risk of a jammed rudder control system on certain Boeing 737 models. This alert was prompted by an incident involving a United Airlines flight that occurred in February.