As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON CLIMB OUT FROM MKE, THE CREW REPORTED A BLEED 2 LEAK MESSAGE ON EICAS. THE QRH WAS FOLLOWED AND THE FLIGHT RETURNED TO MKE AND LANDED WITHOUT INCIDENT. WHILE TROUBLESHOOTING THE FAULT, THE NR 2 PRECOOLER WAS FOUND TO HAVE A LEAKING CORE AND WAS REPLACED WITH NO FURTHER LEAKS NOTED.