Mid 90's I was involved in getting a photograph of a GazelleAH1 inverted with a backdrop of the White Horse at Sutton Bank N.Yorkshire.
After MANY attempts the final photo is a pearler.
I don't have a copy myself that I can locate, but know a man who does and will try and post it.
In answer to the original question a helicopter cant 'fly' upside down as in FW speak. If you were to maintain the attitude, the last thing to go through your mind would be a white nav light!
Its like saying you can jump to the moon, but in reality you can only manage to go about a foot and a half !
Cheers, SS