Thx for the reply. I am talking about RR powered -400's if that makes any diff. All 4 demand pumps are ADP's on ours, so the only source of power when it all goes quiet is the step aside gear box from the core (I think)
Intruder your answer has me wondering though. I would have thought two hydraulic pumps would have put way too much drain on the batt's, mind you, one only has about 20 minutes to worry about it anyway!
X-Check Sorry, should have been clearer in the Q. Talking about the 744, but will be surprised if you tell me the 73 has 4 hydraulic systems!
5 minutes later....
Oooops, just got out the new manuals, you know, the hard to read ones, and it seems that contrary to the old manuals, some of our newer jets do have electric pumps on 2 and 3. But aren't they powered by their respective DC bus, which in turn isn't powered on STBY (batt) power?