A CRJ200 HAS A NOSE DOOR OPEN AND A GEAR DISAGREEMENT INDICATION AFTER TKOF.

Narrative

A NORMAL TKOF PROC WAS UTILIZED WITH REDUCED THRUST. SHORTLY AFTER ROTATION AND AFTER A POSITIVE RATE WAS ESTABLISHED; THE GEAR HANDLE WAS SELECTED IN THE 'UP' POS. SHORTLY AFTER; THE FOLLOWING 2 MASTER WARNING MESSAGES SHOWED UP: NOSE DOOR OPEN AND GEAR DISAGREEMENT. THE NOSE GEAR SHOWED DOWN AND LOCKED (GREEN). THE 2 MAINS SHOWED WHITE. THE QRH WAS FOLLOWED FOR NOSE DOOR OPEN. GEAR HANDLE SELECTED TO THE 'DOWN' POS AND ALL 3 SHOWED DOWN AND LOCKED (GREEN). AN EMER WAS DECLARED AND THE FLT RETURNED TO MHT. A NORMAL APCH AND LNDG FOLLOWED. THE FLT ATTENDANT AND PAX WERE NOTIFIED VIA INTERCOM PA. BTWN THE MOMENT THE GEAR HANDLE WAS SELECTED UP UNTIL WE STARTED THE QRH PROCS TOOK ABOUT 3 MINS. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: IT WAS DETERMINED THAT THERE WAS SWITCH MALFUNCTION. THERE IS A SERIES OF TIMERS ACTIVATED BY RAISING THE GEAR HANDLE. AT 6 SECONDS; THE NOSE GEAR DOOR IS SUPPOSED TOO OPEN. THIS WAS NOT SENSED SO THE SEQUENCING WAS STOPPED; PREVENTING THE RETRACTION OF THE GEAR AND POSSIBLE DAMAGE TO THE DOORS. THIS IS A COMMON PROB IN THE WINTER WHEN OPERATING OFF CONTAMINATED SURFACES. IT IS USUALLY CORRECTED BY CLEANING THE WHEEL WELL AREA.