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’s recommendation comes after at least two incidents in which planes were filled with smoke after large birds struck their engines.

Safety experts recommend that the engines on Boeing’s troubled 737 Max airplanes be modified quickly to prevent smoke from filling the cockpit or cabin after a safety feature is activated following a bird strike.