A320 ENG SHUTDOWN & HYD
 

Does anybody have any reference about when we shutdown both engines and for how long the hydraulic systems will continue to operate?

Good question!
If we have the APU running and the YLO Elec Pump ON, the all is sweetness and light (hydraulically).
However, I assume you were wondering how long a windmilling engine will produce hydraulic power provided of course the Fire Pbs have not been activated.
On reducing IAS for a SE approach with one engine shutdown (Fire Pb not pressed) the PTU will begin to take over hydraulic duties around GD speed.
I’m sure others will chip in too with their experiences in the sim.
Cheers
mcdhu

ouch! ;);)

No reference just observation in the simulator. HYD pressure is sufficient to prevent a Pump Low HYD Px ECAM with the engine windmilling if the speed is maintained around 240-250 kts.

Around 5% N2 windmilling is enough for the EDP’s to stay running. As mcdhu posted you will lose that windmilling at about green dot. Expect the PTU to start kicking in intermittently with transient ECAM cautions.

7% N1 on CFM engines will keep the HYD pressure in green font. Is that what's being asked?

The EDP’s run of the N2 accessory box. Could be 7% N1, but N2 would be a better measure perhaps.

From FCTM "landing with abnormal landing gear":

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As a reverse-engineering method to check how much N2 do you need to get hydraulic pressure, as setting the parking brake after pushback will deplete some pressure from the accumulator, if you don't recharge the accumulator and start No2 keep an eye on the triple indicator, notice when it moves up and then check N2. Now you will know. If I'm not mistaken, N2 above 10-ish will give pressure

👍👍😃 Thanks for all input guys....VERY VERY helpful