NEO - Rudder Trim issue
Thread Starter
NEO - Rudder Trim issue
Some time on a brand new NEO, I experienced the following issue. After start up, and when commencing flight control checks, we noticed that the Rudder Trim had moved to full deflection 25 degrees. We pushed the reset button, and the rudders reset to neutral. After the flight control check, we noticed again, the Rudder Trim went to full deflection of 25 degrees. A second reset, and this happen again, we probably all in all tried 3 - 4 times, before we decided to call it day.
We had engineers and assistance, and performed FAC resets and CB resets, and after this all seemed to work fine. However nobody was able to confirm why this had happen, so we decided to ground the aircraft.
From my knowledge this aircraft was "repaired" and put back into service, before again from my knowledge this happen again twice during ground control checks.
Also somewhere during this Reset procedure we did hear a loud clacking sound, probably as the rudder was moving. With full Rudder input, opposite to the Rudder Trim, we would get neutral trim.
I am just curious if anyone has any idea what could be the reason for this, the aircraft was brand new, less than 100 hours total time since put into operations.
We had engineers and assistance, and performed FAC resets and CB resets, and after this all seemed to work fine. However nobody was able to confirm why this had happen, so we decided to ground the aircraft.
From my knowledge this aircraft was "repaired" and put back into service, before again from my knowledge this happen again twice during ground control checks.
Also somewhere during this Reset procedure we did hear a loud clacking sound, probably as the rudder was moving. With full Rudder input, opposite to the Rudder Trim, we would get neutral trim.
I am just curious if anyone has any idea what could be the reason for this, the aircraft was brand new, less than 100 hours total time since put into operations.
FCOM DSC 27-10-20 has a schematic which may help.
The ELACs compute yaw orders for coordinating turns and damping yaw oscillations, and transmit them to the FACs.
Two electric motors that position the artificial feel unit also trim the rudder. In normal operation, motor N° 1 (controlled by FAC1), powers the trim, and FAC2 with motor N° 2 remains synchronized as a backup.
Something is making a fac produce a yaw order, the problem is finding it.
The ELACs compute yaw orders for coordinating turns and damping yaw oscillations, and transmit them to the FACs.
Two electric motors that position the artificial feel unit also trim the rudder. In normal operation, motor N° 1 (controlled by FAC1), powers the trim, and FAC2 with motor N° 2 remains synchronized as a backup.
Something is making a fac produce a yaw order, the problem is finding it.
