The robinson R44 has, in common with many other types, a fuel usage tracking system. It consists of multiple pistons operating within metal cylinders.
Fuel is drawn into the cylinders and with the application of heat it is made to combust and transfer the ensuing force onto the pistons which then convert this motion into a rotary one.
This process will generate a fair amount of noise.
So . . . . "no noise" = "no fuel"
Hope this helps
