As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
NR 2 ENGINE N1 STARTED FLUCTUATING +/-10% WHILE CLIMBING THROUGH 21,000 FT. THE AIRCRAFT RETURNED TO PHL WHERE MAINTENANCE REMOVED AND REPLACED THE T2C COMPRESSOR INLET TEMPERATURE SENSOR IAW CRJ200 AMM 73-21-09-000(400)-801. ALL GROUND OPERATIONAL CHECKS WERE GOOD. A SATISFACTORY OPERATIONAL CHECK FLIGHT WAS PERFORMED. THE AIRCRAFT WAS THEN RELEASED FOR SERVICE.