loss of tail rotor effectiveness isnt prevalent in large powerful aircraft such as mi-8's, it is more of an issue for small aircraft like jet rangers and oh-58's and maybe Huey's. They didn't even mention it when i moved up the the UH-60 course, but it was a big deal in the oh-58 and ranger. And Ground resonance hasn't been talked about much, i think it might be to knew helicopters having better vibration control and Resistance. Not total sure on that, i would have to do some research.