The Airbus general technical questions topic

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HQ_BRU_Lover
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The Airbus general technical questions topic

Post by HQ_BRU_Lover » 23 Jul 2019, 14:48

Thought it would be a good idea to start a topic with some technical questions around Airbus.

Let me begin first:
- Why do the ailerons bend down when parked? Because of lack of hydraulic pressure when being parked?
- Not all Airbus aircraft ailerons raise after landing I have the impression only "newer" do this. Correct?

What your question around Airbus aircraft?

modeS
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Re: The Airbus general technical questions topic

Post by modeS » 24 Jul 2019, 11:08

When parked the A320 ailerons will be dropped down indeed as long as the hydraulic pressure in the Green and Blue hydraulic system is not sufficient to overcome them from dropping down due to gravity. A similar effect happens with the elevators, but in this case it's related to the pressure in the Green and Yellow system (or Blue system in case of ELAC 2 failure).

When the aircraft is parked, engines will typically be shutdown and in a normal turnaround/cold and dark aircraft state this will result in low hydraulic pressure, leading to the effects described above. There are no relevant hydraulic differences between the A320 CEO and NEO, so both old and newer aircraft have this behaviour. It can however be possible that the hydraulic systems are pressurised on the ground, even when the engines are shutdown. In this case the ailerons and elevators would not be dropped down, which could explain what you saw.

For more detailed info, feel free to check this outdated though still relevant FCOM on section DSC-27-10-20 (page 1-6), DSC-29-10-20, DSC-29-10-30 and DSC-29-20.

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HQ_BRU_Lover
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Re: The Airbus general technical questions topic

Post by HQ_BRU_Lover » 24 Jul 2019, 12:00

Thanks for the confirmation, modeS. Yes I know it doesn't make a difference between the CEO and NEO about the ailerons folding down without hydraulics.

What I meant was when landing, once spoilers are deployed that with "newer" aircraft also the ailerons raise in an upright position - this was not the case on the "original" 32S.

modeS
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Re: The Airbus general technical questions topic

Post by modeS » 24 Jul 2019, 13:18

Ailerons raising after touchdown is indeed a newer feature. It came with the ELAC L97 software update. If the aircraft has ELAC computers with software version L97 or newer, it will feature this behaviour on touchdown.

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HQ_BRU_Lover
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Re: The Airbus general technical questions topic

Post by HQ_BRU_Lover » 24 Jul 2019, 13:56

Thanks again modeS for your input, very much appreciated!

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