What was found
DURING CLIMB OUT ON FLIGHT 3362 CREW REPORTED A LOUD SQUEAL HEARD IN COCKPIT. AT FLT 20,000, CABIN ALT 2600, CABIN RATE AT 0, CAB DELTA P AT 6.6 CABIN RATE DID NOT CHANGE. DECLARED EMERGENCY FOR CABIN PRESS THE ACFT WAS REMOVED FROM SERVICE. BONDED LOWER SECTION OF DV SEAL IAW ETN-EM-56-034, AMM 56-11-00 & R & R DIGITAL CONTROLLER IAW AMM 21-31-01 OPERATIONS CHECKED GOOD. THE ACFT RETURN SERVICE.