At high gross weight near Vne, the response to sudden engine failure in a UH-1H is pretty rough. The Nr bleeds off rapidly and along with the pitch and roll problem the danger of mast bumping is increased. The Army found this in a later test, around 1980. I ran into this problem in a test in 2003 and bumped the mast as well as damaged the rubber mast boot. We were testing the UH-1H with the single PT6 engine and were required by the FAA to document the characteristic of what happens when the engine quits at min rpm, high gross weight at Vne in level flight. This would be the worst case cruise condition. Needless to say operating at 6400N2 near Vne is not a good thing unless you are spring loaded to lower the collective rapidly and keep the rotor in a positive loaded condition. We obtained an STC for the engine conversion but limited all flight conditions to 100% N2, 6600rpm, 324 rpm Nr. Trying to save a little on fuel is not worth the risk. I never beep the rpm down in any flight condition.