Originally Posted by
IO540
A lot of people install a 2nd horizon in place of the T&S/TC because it is much more useful, and flying a precise rate 1 turn is anyway trivial with a horizon (usually 20-22 degrees at a typical IFR tourer cruise speed), and the only time one might be flying precise rate 1 turns is when doing timed turns which is an archaic procedure beloved in partial panel flying (I did most of my FAA IR on timed turns) which one would almost never do in reality, with a battery powered GPS available.
Not sure in Europe but in North America a AI can replace a T & B/turn coordinator provided it is driven off a different power source than the primary AI instrument and has a slip/skid ball incorporated into the instrument. Several companies make electrically driven AI's with a little curved tube style ball built into the base of the instrument so that it can be used as a replacement to the T & B