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Flashcards in Hydraulics Deck (10)
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What does the RAT do?

A drop-out RAT coupled to a hydraulic pump allows the blue system to function if electrical power is lost or both engines fail. Can be deployed manually, can only be stowed on the ground.


When is the PTU inhibited / de-inhibitied?

Inhibited: when park brake ON.
De-inhibitied: when park brake OFF.
Inhibited when yellow electric pump is activated for cargo door (or N/W steering disconnected), during 1st engine start.
Auto test during 2nd engine start.


How is the RAT re-stowed?

Can only be re-stowed on the ground by engineers.


Which systems have fluid shut-off valves? What operates these valves?

Green and yellow, operated when the ENG FIRE p/b is pressed.


When does the BLUE pump start automatically

If aircraft power (1st engine start) is available, the electrical pump operates: in flight, on the ground, if one engine is running.
If the crew has presses the BLUE BUMP OVRD p/b on the maintenance panel.


When does the FAULT light (on the OHP) Extinguish following a reservoir overheat?

The light stays on as long as the overheat lasts.
Extinguish when overheat ceases.


What is meant by OVHT on the SD (Yellow and Blue electric pumps)?

Appears in amber if the electric pump for that system (blue or yellow) overheats.


What causes FAULT lights to illuminate on the OHP?

The reservoir level is low, overheats. Air pressure is low, pump pressure is low, inhibited on the ground, when the engine is stopped, goes off if selects OFF except for overheat.


What causes the yellow electric pump to run / stop automatically? Is the yellow system fully operational when the pump is running?

It comes on automatically when a crew sets the lever of the cargo door manual selector valve to OPEN or CLOSE.
No, it inhibits the operation of the other system functions except alternate braking and engine 2 reverse. When door selector valve open or closed.


What are the normal and RAT operating pressures?

Normal system operating pressure is 3000PSI (2500PSI when powered by the RAT).