Reengaging autotrim on the A320

[grodan]

Hi all,

I cant seem to find information on reengaging autotrim on the A320 after it has been disabled by manual movement of the trim wheel.

Example scenario: during cruise, I accidentely move the trim wheel. Do I have to keep trimming manually for zero elevator deflection until the end of the flight, or is there a way to get the autotrim back?

Thanks!

[Field In Sight]

Manual trim has priority. So if you move it, you override the auto trim. If you let go, it should revert to automatic.
A captain at a previous airline moved it in flight and the aircraft reverted to ALTN law and didn't revert back.

Hope that helps.

[grodan]

Thanks for the reply!

As for the alternate law reversion, why do you think that happened? Maybe the ELACs couldn't come to terms with the THS movement uncommanded by them, decided that it is a control fault and decided to bug out resulting in alternate law?

[Fursty Ferret]

Originally Posted by grodan

Thanks for the reply!

As for the alternate law reversion, why do you think that happened? Maybe the ELACs couldn't come to terms with the THS movement uncommanded by them, decided that it is a control fault and decided to bug out resulting in alternate law?

It shouldn't have happened. There are force sensors on the pitch trim wheel that signal to the ELACs that a manual pitch trim input is being made. They should immediately resume auto trim once it's released.

Could be that one of those sensors was faulty and the ELAC interpreted it as a THS jam, which will see you end up in alternate law.