A CRJ200 developed a flap asymmetry after take off. The asymmetry was felt in the flight controls and indicated on the EICAS flap synoptic page but not indicated on the flap gauge.

Narrative

After takeoff; during flap retraction; the left flap froze at 4 degrees and was accompanied by a roll tendency. The flap remained frozen for approximately 5 - 8 minutes and then slowly made its way to a 0 degree condition. There was not an associated FLAPS FAIL message however. We did refer to the QRH for FLAPS FAIL and discussed the issue with the First Officer and also with maintenance. The First Officer and I felt that it would be prudent to continue with the QRH and run the FLAPS FAIL checklist. We then ran the FLAPS FAIL checklist and notified ATC of our issue and requested the longest runway and also requested emergency personnel to standby as a precaution. The landing was uneventful and we taxied to the gate with no further incident. At the gate; maintenance was contacted and a detailed notation was made in the can. The event occurred due to a malfunction of the flap system. As explained above; due to the unknown condition or operational ability of the flaps; we did elect to proceed with the QRH FLAPS FAIL procedure. While conferring with the First Officer; this decision was made in order to avoid landing in an undesirable and untrained configuration. We felt that it would be more desirable to land Flaps 0 (a condition that we are trained to do) than risk operating the flaps and them failing unevenly (perhaps at a lower altitude when going from say 30 degrees to 45 degrees). The emergency was declared solely as a precaution due high approach and landing speeds. In all; we felt that this was the most conservative approach to this unique problem.