Hydraulics Flashcards
What are the normal and RAT operating pressures?
3000 psi Normal
2500 psi RAT
What does the RAT do? When does it deploy automatically? How is it restowed?
Allows blue hydraulic system to function in case of dual engine failure.
Deploys automatically if AC BUS 1 and AC BUS 2 are both lost.
Can only be restowed on the ground.
What happens to the hydraulics after 1st ENG started?
HP bleed air pressurises the hydraulic reservoirs
What causes the yellow electrical pump to run/stop automatically?
Cargo door set to open/close. A other systems inhibited apart from alternate braking and eng 2 reverse.
When does the PTU run automatically? When is it self tested?
To transfer power between green and yellow systems when the pressure differential is greater than 500 psi.
Self tested on second engine start. (Inhibited on first)
When is the PTU inhibited?
40 seconds after the end of cargo door operation
During first engine start.
With only one ENG master SW on and parking brake on.
Which hydraulic systems have fluid shut-off valves? What operates these valves?
Green and yellow. ENG 1 (2) fire button.
How do you pressurise the green HYD system prior to engine start?
Via yellow electric pump and PTU
When does the FAULT light on the OHP extinguish following a reservoir overheat?
Only when the overheat condition has ceased.
Within the HYDRAULICS system, what happens after the 1st engine started?
Blue system is pressurised
