TKE: Hydraulic System

Normal hydraulic power is provided by:

• Engine driven pumps for all systems

• Engine driven pumps for green and yellow, ELEC pump for the blue, ELEC pump for yellow (ground operation only)

• Electric pumps for blue and yellow, engine driven pumps for green

• Engine driven pumps for green and blue electric pump for yellow

The power transfer unit (PTU) is:

• reversible between green and yellow

• one way between green and yellow

• reversible between all three systems

• reversible between blue and yellow

In flight, if Blue ELEC pump fails, Blue system:

• is lost

• can be recovered by RAT

• can be recovered by PTU

• Both b and c

With both engines stopped, how is it possible to pressurize the Green system:

• By the green engine pump

• By the yellow engine pump and the PTU

• By the yellow electric pump and the PTU

The RAT is automatically extended in case of

• Blue pump failure

• Blue pump delivery pressure dropping below 1750 psi

• Loss of (ENG. and APU) main generators

• Can only be deployed manually

On ground the Blue system is pressurized when:

• the APU is running

• one engine is running

• EXT power is available

Engine 2 energizes:

• the blue system

• the green system

• the yellow system pump and the green system via the PTU should the green system pump fail

The yellow system comprises:

• one engine driven pump, one electric pump, one hand pump

• one engine driven pump, two electric pump

• one engine driven pump, one hand pump and the RAT

The PTU runs automatically when delta P between the green and yellow system is more than 500 psi.

• during green or yellow reservoir fluid low level

• during green or yellow reservoir low air pressure

• during green or yellow system low pressure

The priority valves operate in case of:

• high hydraulic pressure in the green system

• low hydraulic pressure

• high hydraulic pressure in the green and yellow system