NTSB issues safety bulletin for Boeing 737 max engines

(CNN)– The National Transportation Safety Board is issuing a rare “urgent” safety warning of potential problems with the Boeing 737 max.

The recommendation follows two incidents on Southwest Airlines flights that hit birds.

The NTSB found issues with the engines that when damaged can cause smoke to enter the cabin and cockpit.

Smoke in the cockpit is classified as an extreme danger in aviation as it can overcome and incapacitate pilots.

The NTSB is asking the federal aviation administration to inform flight crews of airplanes with these engines to be aware of the potential issue.