As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
R PACK INOP LIGHT EICAS MSG AND OVERHEAD. AIRCRAFT BACK TO BLOCK AND GROUNDED BY MAINTENANCE. MAINTENANCE FOUND PRV CONTROLLER INOP. PRV CONTROLLER REPLACED IAW AMM 36-11-19/401 TESTED OK ENGINE RUN PERFORMED NO LEAK FOUND AIRCRAFT RELEASED ETOPS 180, AIRCRAFT RETURNED TO SERVICE.