AN EMB-135 FLIGHT CREW NOTICED THE SOUND OF NOSE GEAR DOORS OPENING AFTER TAKEOFF WITHOUT ANY ABNORMAL INDICATIONS. THEY COORDINATED WITH OPERATIONS AND MAINTENANCE; DECLARED AN EMERGENCY; AND RETURNED TO LAND.

Narrative

DURING CLBOUT ON A R DOWNWIND DEP OFF RWY AT ZZZ; PASSING 7500 FT MSL; THE SOUND OF THE NOSE GEAR DOORS OPENING WAS WITNESSED BY BOTH PLTS AND THE FLT ATTENDANT; SITTING IN HIS CABIN JUMPSEAT. THERE WAS NO OTHER INDICATION; NOR EICAS MESSAGE; MASTER CAUTION; MASTER WARNING; NOR ANY COM OF ABNORMAL OR FAILED CONDITION. HYD AND OTHER SYS PAGES WERE NORMAL AND HYD WAS MONITORED. ATC WAS NOTIFIED OF OUR INTENTION TO RETURN TO ZZZ DUE TO ABNORMAL CONDITION; PENDING COMPLETION OF CHKLISTS AND CONSULTATION WITH ACR STAFF. EMER WAS DECLARED; OPS AND MAINT WERE CONSULTED. FLT ATTENDANT AND PAX WERE BRIEFED; FULL BRIEF FOR POSSIBLE ABNORMAL LNDG. ZZZ OPS AND MAINT WERE CONSULTED AND BRIEFED. SUBSEQUENT TO EXHAUSTION OF CRM CAPACITIES AND CONSULTATION OF MANUALS; A GEAR DOWN FLYBY OF THE CTL TWR WAS PERFORMED. TWR RPTED AND THE CREW EXPERIENCED NORMAL CONDITIONS FOR LNDG CONFIGN. PAX AND FLT ATTENDANT RE-BRIEFED AND A NORMAL FLAPS 45 DEG LNDG WAS COMPLETED TO A FULL STOP ON RWY. FOLLOWING CFR AND MAINT INSPECTION; GEAR WAS PINNED AND ACFT WAS TAXIED TO GATE. FAILURE OF NOSE GEAR DOOR CTL.