What was found
LOUD SQUEAL COMING FROM THE CAPTAIN`S SIDE WINDOW. IT STARTED DURING CLIMB, PASSING THORUGH 21,000 FT, CABIN ALTTITUDE OF 5,000 FT APPROXIMATELY. STOPPED DURING DESCENT BELOW 13,700 FT. THE AIRCRAFT WAS GROUNDED. MAINTENANCE FOUND SEPARATION OF THE WINDOW CAUSED THE LOUD SQUEL. REMOVED AND REPLACED THE L2 WINDOW AND L2 WINDOW SEAL IAW AMM 56-11-02, AND 56-11-11. OPS AND LEAK CHECKED GOOD.