Hi,
I've finally found the bug !!!

It was a nasty one, but I've smashed it!!

The problem is related with the function that switch damages from tail to engine and vice versa and with the fact the the Rudder Jam damage is a Red chit, while the "Engine damaged: no speed 3 or 4 maneuvers 2 Engine" is a Blue one.
This combination of change both type and color of damage caused the bug.
now is fixed!

Have red and blue fun,
Nick.