During the Vietnam war, hundreds of soldiers suffered serious burn injuries following otherwise survivable Huey helicopter crashes. In 1970, Bell Helicopter responded by developing a crashworthy fuel system and installing it in the new Hueys it produced. The crashworthy system included stronger fuel cells, breakaway fuel lines, and cutoff valves.
The Army kept track of the effectiveness of the new fuel system. Over the next 39 months, 895 helicopters without the new system crashed. Post impact fires resulted in 52 burn fatalities and 31 burn injuries. Over the same time period, 702 helicopters with the new crashworthy fuel system went down. Remarkably, there was not a single thermal injury or death in any of those crashes. That was enough to convince the Army. After that, it required all its helicopters to be manufactured with the crashworthy fuel system.
Today, no one should be burned in an otherwise survivable helicopter accident. The technology has long existed to almost completely eliminate post-crash helicopter fires. But while the risk has been virtually eliminated in military helicopter operations, post crash fires are still the single biggest hazard to survivors of civilian helicopter crashes. (pdf) That's because some civilian helicopter manufacturers have resisted incorporating crashworthy fuel systems into their designs.
Helicopter manufacturers know that some of the aircraft they manufacturer will inevitably be involved in accidents. They must take steps to make their civilian helicopters reasonably safe in the event of an accident, just as they do when building helicopters for the military. If someone is burned in a civilian helicopter crash, then the aircraft's design may well be proven to be defective, and the manufacturer held accountable for the injuries its design has caused.