What was found
ON FLIGHT 4208 THE CREW REPORTED THAT ON CLIMBOUT AT APPROX 225 KNOTS THE CREW HEARD A LOUD BANGING FROM NOSE GEAR AREA IT INCREASED AS THEY ACCELERATED TO 240 KNOTS. THE CREW DECLARED AN EMERGENCY AND RETURNED TO BWI. THE AIRCRAFT WAS REMOVED FROM SERVICE. FOUND NOSE LANDING GEAR UPLOCK SWITCH POO42 FAULTY. REMOVED AND REPLACED NOSE LANDING GEAR UPLOCK SWITCH POO47 AND SAME HARNESS IAW EMB 145 AMM# 32-61-01/32-62-00. INSPECTED ALL LANDING GEAR UPLOCK SWITCHES CHECKED GOOD IAW SWPM # 20-50-00. EXTENSION AND RETRACTION TEST GOOD IAW EMB 145 AMM # 32-30-00/32-62-00. THE AIRCRAFT WAS RETURNED TO SERVICE.