B747 Hyd Qty Low 1
In the HYD QTY LOW 1 non-normal checklist for the B747, it gives us two possible choices. If the HYD PRESS SYS 4 is not shown, procedure states for the flight to continue normal operation. If HYD PRESS SYS 4 is shown, then there will be some procedures to follow.
As for the HYD QTY LOW 4 non-normal checklist, the QRH does not provide the given step : If the HYD PRESS SYS 1 is shown.......
What is the reason for that? Does it have to due with the service bulletin : Potential Sequential Loss of Multiple Hydraulic Systems?
I am a junior first office and would very much appreciate any help. Thanks in advance.