During climbout, the pilot smelled smoke in the cockpit area. An investigation revealed the smoke was coming from the avionics master switch (P/N CM3589-50). He notified the tower before shutting down the avionics master switch.

The submitter stated the same problem was found on two additional aircraft in their fleet. The FAA Service Difficulty Reporting Program data base revealed 29 reports of avionics master switch (P/N CM3589-50) failures.

Part total time-814 hours.