>but since there is probably insufficient bleed air in this scenerio to run an ADP, I only mentioned the 3 HMG-type 767. The windmilling engines and the EDP's are more likely, however, to provide power to the HMG's on the L & R Hydraulic systems (or have I overlooked something obvious?).
To my knowledge, there are no 767s with 3 HMGs. For ETOPS 767s, there is one HMG (Hydraulic Motor Generator, now Hydraulic Driven Generator), powered by the ADP, which receives air from the Center Pneumatic Duct. The source of the air is whatever is pressurizing the center duct.
The electric hydraulic pumps are A.C. powered.