What was found
AIRCRAFT WAS GROUNDED: PILOT DECLARED EMERGNECY AND RETURNED TO PHL ON ACCOUNT OF LOSS OF BOTH PACKS AND LOSS OF CABIN PRESSURIZATION. AIRCRAFT DECENDED TO 10,000FT. FROM FL370. MAINTENANCE ACCOMPLISHED FIM TASK 21-51-00 FIG 104 AND FOUND THE LEFT RAM AIR EXHAUST ACTUATOR FAILED IN THE CLOSED POSITION. REPLACED ACTUATOR IAW AMM 21-53-04-401. MAINTENANCE ALSO FOUND HEAT EXCHANGER EXHAUST PLENUM DAMAGED/HOLED. REPLACED PLENUM IAW AMM 21-51-02-401. LEFT PACK OPS CHECK OK IAW AMM 21-51-00. SEE SDR # AALA201905039033.