Hi flyingtonka,
I know one helicopter (5 to be excact), where multicrew is required.
BK 117 in NVG-operations.
After fitting FLIR and NVG-equipment in our BK117-fleet, the stuff had that to be approved.
Some more pages in the book - and its written down, NVG-operatins only with a crew of two Pilots.
Was done at Alanmann (
http://www.alanmann.co.uk/engineering/#)
Greetings Flying Bull