B757 Hydraulics tricks
I found answer to
3-Why QRH says "Do not arm Speedbrakes· everytim we loose 2 Hydraulics?
Answer could be:
The main gear trucks remain un-tilted during alternate gear extension, which is the final signal for the automatic speedbrake extension. If the speedbrakes were armed, alternate extension used and the thrust levers subsequently closed at some point during the approach, the speedbrakes would extend fully
But now another question comes up:
Ok that if we loose L and R Hyd,we ll need Alt Gear extension so no Tilt so we should not arm speedbrake.
But why does QRH also mention "Do not arm speedbrakes" with the other combinations of 2 hydraulics failure?
I mean:If we loose C&R we don t need alternate Gear,and if we loose C&L and PTU works we don t need Alt Gear either.SO why do they still say "do not arm speedbrake" f Gear will be putted down with normal opertion so tilted strucks?