What was found
(CAN) DURING GROUND RUNS AFTER COMPLETION OF A HEAVY MAINTENANCE CHECK MAINTENANCE PERSONNEL WERE NOT ABLE TO PRESSURIZE THE AIRCRAFT WITH THE ENGINE BLEED AIR WHILE IN MANUAL MODE. MAINTENANCE TROUBLESHOOTING IDENTIFIED A NUMBER OF CRACKS AND INTERNAL DAMAGE TO THE DUAL HEAT EXCHANGER. (PN 820905-3, SN 2010011192). THE DUAL HEAT EXCHANGER WAS REPLACED WITH A SERVICEABLE UNIT, GROUND RUNS COMPLETED AND TESTED SERVICEABLE. AIRCRAFT HOURS: 22357 AIRCRAFT CYCLES: 17140 (TC# 20190506008)