"This is Chopper Dave's made for TV movie, Blades Of Vengeance. See, he's a chopper pilot by day, but by night he fights crime as a werewolf... YEAH!"
In the tradition of "Space Ghost Coast to Coast", the adult animated series "Sealab 2021" lifted footage from an old, obscure Hanna-Barbera kiddie cartoon show, reedited the material, and composited the images over newly drawn backgrounds. In this case, the "original" series was "Sealab 2020", which was first seen on NBC during the 1972-1973 season. One of several "serious" H-B efforts of the era, the first "Sealab" took place in the early 21st century and was set in a domed experimental city several miles beneath the sea.