What was found
AIRCRAFT WAS GROUNDED: AN EMERGENCY WAS DECLARED DUE TO: R2 COCKPIT WINDOW DID NOT PRESSURIZE AFTER TAKE OFF, EXTREMELY LOUD HISSING SOUND. AIRCRAFT DIVERTED TO AND LANDED SAFELY AT MSP. INSPECTED R2 WINDOW AND SEAL, PER AMM 56-12-11. NO DEBRIS OR DAMAGE NOTED. PRESSURIZED AIRCRAFT TO 4 PSI, PER AMM 05-51-91. NO LEAKS NOTED NEAR R2 WINDOW. NO FAULT FOUND.