Software updates don't always require the FADEC to come off wing. The CFM engine on the 737NG for example can receive software updates very easily on wing. After completion, no engine run is required and of course both FADEC's have to be updated at the same time in order to maintain software commonality.
Even I am suprised at that one
I would have thought at least a ground idle run would be required even if its just to check for any generated faults. Would have thought some defects will only manifest themselves on a running engine.
