timmyEGCC
At 300KTS wind milling is sufficient to keep hydraulics working. At FL250 start the APU. As speed is reduced for approach wind milling will not sustain hydraulics. You can use yellow electrical pump with PTU OFF as Yellow electric does not have the capacity to support green through PTU. With blue and yellow working you can move both slat and flap but slowly. ECAM should tell you all this.