A Kaman K-MAX Twin-Rotor Heavy-Lift Helicopter Starting Up Viewed Directly from the Front ...
... which, incidentally, allows us to be clear about which way the blades rotate – whether it's forward @ the centreline or rearward there ... & evidently it's the former – ie forward @ the centreline.
 
From
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This Facebook post
https://www.facebook.com/story.php?story\_fbid=10162702526975112&id=10162702527060112 .
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Forgot to put the attribution in, @first! 🙄 ... which is why I deleted this & posted it again ... although probably very few folk noticed that.
It's actually very generous of the goodly author of that Facebook post to allow downloading of the video so easily.
u/Frangifer — 15 hours ago