Hydraulics, B738

[KristianNorway]

Hello flying friends

I'm planning to look through the books on these topics now, but it's always interesting to get perspectives and feedback from this forum.

Can anyone tell me to what component the EMDP is coupled in the engine? I expect it to be the N2. Is that right?

And for you simulator-instructors:

When you select engine seizure; Is that a seizure on only the N1 fan stage?
What is then the effect on the N2-stage?

To wrap it up: In case of a birdstrike on both engines and a corresponding dual engine N1 or both N1/N2 seizure. Would you revert to manual reversion?

Thanks

[CaptainSandL]

The engine driven hydraulic pumps are driven by the N2 section via the accessory gearbox. Therefore if the N2 has seized you will not have the pump. If the N2 is still windmilling you probably will still have the pump but it depends upon your IAS. At 300kts the N2 will stabilize at about 15% which should be enough.

If both engines have seized then start the APU for elecs to power the elec hyd pump.

[KristianNorway]

Thanks for a quick response!

But one last thing: A seizure in the sim gives you only N1 seizure or N1/N2?

And let's say you don't start the APU with dual seizure; Do you then revert to manual reversion?

[CaptainSandL]

A seizure in the sim gives you only N1 seizure or N1/N2?

You have to look at the N2 gauge, dont try to second guess what failure was input.

let's say you don't start the APU with dual seizure

Why would you not start the APU? If it is also U/S then with two seized N2's and no AC electrics you will lose hydraulic pressure.

Do you normally get this much of a hard time in the sim?

[KristianNorway]

Hehe.. I understand that the question seems a bit odd. I'm asking hypothetically just to get an understanding of the technical aspect of it. That's also why I'm pressing the question without the use of the APU when you present a practical solution. Of course one would start the APU.

Our sim sessions and instructors are very good, no worries

Again thanks.

[mebijus]

I guess you'll be doing all engines out on simulator,no ac power.Just make sure to be over outer marker twice the normal altitude,and you will be OK.

[VJW]

I fly the 738, the day I have an APU inop follow by a seizure on each engine- it really isn't my day!