Airbus RAT
 

Is there a max speed for the RAT at various buses?

the RAT speed is controlled by the by the governor unit in the RAT which varies the blades AOA to keep it within limits if i remember correctly

And just to answer the question: No there is not.

I can't recall all of the specifics nor what Abusses other than the 320 were affected but there was an AD recently on A320 RAT deployment during flight testing.

Apparently some authourities require regular flt test verification of RAT deployment/operation so the the airspeed during the testing is limited to 250kts during verification flt tests to reduce cycling fatigue.

This is very interesting. I have heard about that through the grapewine as well.
Thx