For cruise, propeller rpm is back to 1500 and the low speed, along with passive noise dampers and sophisticated sound insulation packed in bags behind the interior, makes for a very quiet and smooth ride. The four-blade Hartzell propellers are dynamically balanced to each airframe. We had propeller heat on for a big chunk of the trip because we flew in cold clouds, but, as often happens, no ice formed. The 350 series is fully certified for flight in icing with electrical heat for the props, windshield and probes, and pneumatic boots to protect the leading edges. Engine air inlets are continuously heated by hot exhaust.