Again thanks for the replies. I'll try to answer in order. Just a recap, in an Ar234, engine damaged/shutdown. Autopilot on, level flight. With the CT engaged the aeroplane wont hold a heading, i.e it gradually turns towards the dead engine, which is expected. I turned off the CT, and trimmed it out. The trim automatically returned to neutral.
Colmbo.. Thanks I will try and trim it without the autopilot engaged.
DmonSlyr. The autopilot was already engaged, i just turned off the CT and then manually trimmed it.
FES67. I normally dont touch the trim, in buffs that is, with the exception of damage.
Morfiend. I will try that and report back.
Bozon. Could be, but as the autopilot was engaged, I didn't check the trim light.. will do that.