Small Transport; Low Wing; 2 Recip Eng
Flight Crew Multiengine; Flight Crew Private; Flight Crew Instrument
Flight Crew Last 90 Days 75; Flight Crew Total 5000; Flight Crew Type 100
Conflict NMAC
General None Reported / Taken
Airport; Procedure
I was on an IFR flight to UGN. Chicago Center had handed me to the Tower at UGN. I was cleared for the visual approach to Runway 5; directed to report midfield left downwind for Runway 5. My TCAS alerted me to traffic; both audible and visual; and I then saw a single engine out the right side; approximately 300 FT away at my altitude. There was no warning of the traffic. I did report that I had observed traffic; but did not report a near miss to the Tower. I reported the midfield position and was cleared to land. There was no further incident. On the ground I played back several times the Tower transmissions to listen for advisory I might have missed; but there were none given.
An pilot reported a near miss at 2;000 FT while in the UGN traffic pattern with no traffic alert from ATC.