Re-design  

For real, so much thought just doesn't seem to make its way into the design process. 

I'm curious how this company, Hill Aviation, will turn out and if they truly revolutionize aviation:

https://www.flightglobal.com/helicopters/hill-helicopters-unveils-disruptive-hx50-but-has-mountain-to-climb-to-bring-it-to-market/139893.article

For real, there's just no good reason the aviation engineering community can't put some valid and simple concepts into their designs and manufacturing.  

For example, look at the "Quiet One" (MD-500P) they made in Vietnam.  Took a 91 decibel helicopter to 71 decibels.  Largely because they added a set of blades to the tail rotor and reduced the gearbox ratio to slow it down (part of the reason the AH-64 tail rotor is almost completely silent).  There's no reason they can't do that to all helicopters today.

https://www.youtube.com/watch?v=g0NBhbrKvCI (go to 1:22 to hear the sound comparison).