Looking at the currently running A330/A340 elevator SCU retrofit programme, I am still unsure whether it is a good idea to take all for of them out at the same time, modify them, and reinstall them - and no test flight is conducted afterwards.
The AMM is kind of vague concerning such a job (I mean the testflight...

), and it is the understanding of various engineers that you donīt need a "live" test in the air...
Cheers,
J.V.