As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING PUSHBACK WE LOST RT AC BUS DURING RIGHT ENGINE START. AIRCRAFT RETURNED BACK TO BLOCK AND WAS GROUNDED. MAINTENANCE REMOVED AND REPLACED BPCU, IAW B767 AMM 24-41-03. OPERATIONS CHECK GOOD. AIRCRAFT RELEASED, AIRCRAFT REMAINS ETOPS 180.