Certainly not necessary to deploy the RAT on the 767. The 757 should be the same I thought.
It is important to recognise the difference between hydraulic
pump failures and Hydraulic
system failure. Hyd System failure would normally be the result of fluid loss.
Best to follow the manufactirers recommended non normal procedure. If we are dealing with C1 and C2 electrical
pump failure it says turn the affected pump(s)with pressure light(s) illuminated off and then if the
demand pump. .pressure light is on put it to ON.
Normally the Air Demand Pump (Centre Hyd Demand Pump) will operate automatically with only C1 & C2 pumps off so the Centre system is still operative anyway.
