We are using C-130 B and E Models with T-56 A-15 engines and Hamilton Sundstrand 54H60-91/117 propellers. A lot of vibration and resonance are felt on these military version aircraft even after using solid state synchrophasing and conducting prop balancing.
I wanted to know if there is some system to make the aircraft quieter. Except for shutting down the engines of course :)
Are there any resonance controlling items to make the passengers more at ease?