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A320 THS drive question

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A320 THS drive question

Old 4th Jul 2022, 21:24
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A320 THS drive question

Doing my A320 rating... 10 yrs after the majority of PPRuNe users it seems

The CBT uses (to me) odd wording describing the THS drive: the hydraulic motors are driven by one of three electric motors.

Having read and listened over and over again, I interpret it as electric motors position control valves deciding direction of rotation of the hydraulic motors, but It's still the hydraulics that drive the hydraulic motors that run the jackscrew? Is this correct? For manual trim the control valves are positioned mechanically, and we still need hydraulics to run the THS?
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Old 4th Jul 2022, 21:53
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Yes, you need green or yellow hydraulics to actually move the THS. The electric motors only effect control of the hydraulic motors; not sure exactly how, but without hydraulics, the THS cannot move.
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Old 5th Jul 2022, 06:02
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Originally Posted by 172_driver View Post
Doing my A320 rating... 10 yrs after the majority of PPRuNe users it seems

The CBT uses (to me) odd wording describing the THS drive: the hydraulic motors are driven by one of three electric motors.

Having read and listened over and over again, I interpret it as electric motors position control valves deciding direction of rotation of the hydraulic motors, but It's still the hydraulics that drive the hydraulic motors that run the jackscrew? Is this correct? For manual trim the control valves are positioned mechanically, and we still need hydraulics to run the THS?
​​​​​ Flight controls are electrically controlled and actuated through hydraulic servo jacks. In case of complete electric or computer failures mechanical back up is provided for stabilizer and rudder. Airbus flight controls cannot be moved without hydraulics.
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Old 5th Jul 2022, 06:53
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Thanks,
Sounds like we're all in agreement then.
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Old 5th Jul 2022, 07:54
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Just to add; IF you are having a very bad day and have lost both green and yellow hydraulics, you will have lost the THS movement, but you will still have both elevators from the blue hydraulic system. So you retain some pitch control.
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Old 5th Jul 2022, 10:17
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Some pitch control? Quiet a good control actually till gear is up and if lowered as recommended then even with gear down.
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Old 5th Jul 2022, 15:18
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I think I am practicing for my Air Force career will all these F/CTL computers! Except the protections seem to be somewhat restricting me
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