The National Transportation Safety Board has recommended design changes to the engine covers on thousands of Boeing aircraft.
The directive came as the NTSB met to discuss the cause of an engine explosion on a Southwest Airlines flight last year.
It led to the first accident-related death on a US airline in over nine years.
The NTSB determined that engine blades were likely already cracked at the time of the plane’s previous engine overhaul but it wasn’t spotted at the time.
Inspection methods have since been revised.
The accident sparked widespread inspections and more than a dozen other aircraftt across multiple airlines were found to have cracked blades in the in engines made by CFM International.
The safety board has asked Boeing to redesign the engine covers which would include retro fitting planes already in service.
Boeing insists the 737 NG is safe to fly and will take onboard the recommendations.
"Boeing is committed to working closely with the FAA, engine manufacturers, and industry stakeholders to implement enhancements that address the NTSB’s safety recommendations," the plane maker said.
"Our common goal is to help prevent similar events from happening in the future."
