Originally Posted by fly3
If you land with out doing this there is a possibility that you will run out of authority steering to the side that has the trim
I always thought that the rudder trim on the A320 only influenced an artificial feel unit and had no influence on the maximum rudder deflection or nosewheel steering limit! If so, the pilot would perhaps need to use more force, but full rudder travel would still be available. That would explain why the FCTM uses the wording "the rudder trim can be reset" during OEI approach instead of saying that it should be reset to zero.
So I went looking for clues in the FCOM to back up my point of view. This is what I found: (make sure to read the bold print)
Originally Posted by FCOM DSC 27-10-20
The two electric motors that position the artificial feel unit also trim the rudder. In normal operation, motor N° 1 (controlled by FAC1), drives the trim, and FAC2 with motor N° 2 remains synchronized as a backup.
In manual flight, the pilot can apply rudder trim with the rotary RUD TRIM switch on the pedestal.
- Maximum deflection is ± 20 °.
- Rudder trim speed is 1 °/s.
- In addition to limitation by the TLU, if rudder trim is applied, maximum rudder deflection may be reduced in the opposite direction.
The pilot can use a button on the RUD TRIM panel to reset the rudder trim to zero.
So this confirms that rudder trim works through an artificial feel unit, but at the same time says that max. rudder deflection may be reduced.
So here's what I dislike about the A320 FCOM: the lack of correct clear information! Surely one would think that rudder trim should be reset if rudder deflection is affected. Why use the word "may" in the FCOM?
It either does reduce rudder deflection in certain conditions or it doesn't! I still think that it doesn't and I'm tempted to try it on my next flight: after engine start, put a significant amount of rudder trim in (10 or so) and check the F/CTL page for full rudder deflection when testing it. (I won't forget to put the trim to neutral again before taxi.
But, anyway, even if my numerous sim sessions over the last 11+ years, and instructors' feedback have never demonstrated the necessity to zero the rudder trim before OEI ldg, I will be doing it in the future just to be on the safe side.
Thanks for the input, Fly3 and vilas.