As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW REPORTED HYD SYS 1 OVERTEMP MSG ON EICAS DURING CLIMB, DECLARED AN EMERGENCY AND RETURNED TO FIELD. MAINTENANCE T/S PER AMM AND REPORTED ACMP NR 1 WAS AT FAULT. MTX SWAPPED ACMP NR 1 WITH ACMP 3B AND PLACED ON MEL. A/C WAS THEN RETURNED TO SERVICE.