As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: FIRST OFFICER'S R2 LEAKING AIR WITH A HIGH PITCHED WHINE, DRAIN HOSE STUCK IN WINDOW. FLIGHT RETURNED TO CUN LANDING SAFELY. MAINTENANCE FOUND FORWARD DRAIN HOSE BETWEEN WINDOW PRESSURE SEAL AND FRAME. ACCOMPLISHED R2 OPENABLE WINDOW OPERATIONAL CHECK PER AMM 56-12-11-710-803. CONFIRMED R2 WINDOW PROPERLY CLOSED AND LOCKED.