UH-60M has a problem with tail boom strikes doing tactical landings the UH-60A/L didn't have , the A/L had metal blades with the sweep at the tip of the blade flat , when the Black Hawk was thrown on the ground the stiffer metal blade still clears the tail, the newer UH-60M with new wide cord composite blades has a swept tip that angles down and are a softer blade , if you throw a UH-60M onto the ground with the same vigour as a UH-60A/L you will have a blade strike on the tail , pilots coming from older metal blade versions have to learn a new less vigorous tactical landing in the UH-60M.