What was found
DURING CLIMBOUT AFTER TAKEOFF FROM PIT THE CREW OF FLIGHT 2377 NOTED THE CABIN ALTITUDE READING 11,000FT, IT THEN WENT TO 7000 FT AND THE CABIN ALTITUDE WAS CLIMBING WITH THE AIRCRAFT. THE CREW HEARD A LOUD NOISE AND FELT AIR ESCAPING FROM THE COCKPIT ESCAPE HATCH. THE AIRCRAFT RETURNED TO PIT AND MADE AN UNEVENTFUL LANDING. MAINTENANCE AT PIT CLEANED AND INSPECTED THE CREW HATCH SEAL AND FOUND NO DEFECTS. THE AIRCRAFT WAS PRESSURIZED IAW CRJ 200 AMM 21-31-10-710-801. THE PRESSURIZATION SYSTEM OPS CHECKED GOOD AND NO LEAKS WERE FOUND. THE AIRCRAFT WAS THEN RETURNED TO SERVICE.