Many think that, after it completes an investigation, the NTSB can order a stop to the dangerous practice that it determined was the cause of the aviation accident.  Not so.  The NTSB has no regulatory power at all. The only thing the NTSB can do after an investigation is make a safety recommendation and hope that the FAA

There’s little question that EMS helicopters are the most dangerous aircraft in the sky. EMS helicopters have a fatal accident rate 6000 times that of commercial airliners. Flying EMS helicopters is one of the most dangerous jobs in America.  In fact, according to the Washington Post, only working on a fishing boat is riskier. 

A reader of this post concerning air ambulance accidents asked, “Can the FAA really get away with ignoring the NTSB?"  The answer, to date, is "yes."  And there’s nothing the NTSB can do about it.

The whole reason the NTSB exists is to learn from accidents and make safety recommendations so that similar accidents won’t happen again.