The National Transportation Safety Board warned that certain CFM engines installed in some Boeing 737 Max jets may feed smoke into the cockpit or cabin after a bird strike.

US safety investigators called for urgent action to be taken in response to an engine issue on Boeing Co. 737 Max aircraft that can lead to smoke in the cockpit or cabin.

The National Transportation Safety Board issued a rare, urgent safety bulletin warning of potential problems with the jet engines on Boeing 737 Max aircraft. The recommendation was inspired by two incidents on Southwest Airlines flights that hit birds.