A few decades ago I did my Ag rating with a very experienced Ag pilot in a Hiller 12E(bladder fuel tank), & back then he refused to fly in a Bell 47 due to its propensity to burn after a heavy landing as the fuel tanks came down through the engine bay. I'm too young & internet chat forums weren't around at the time, but I wonder if this same conversation was had at the time about Bell 47's? Deja-vu all over again, we're slow learners.