What was found
AFTER T/O, THE AIRCRAFT WAS TURNED BACK TO DEPARTURE BASE DUE TO PRESSURE SYS 1 FAILURE AND UNABLE TO CONTROL PRESSURIZATION AFTER SWITCHING TO SYS 2. LANDING IN MANUAL MODE WITH NO INCIDENTS. FUEL AUTO FEED FAULT WAS REPORTED. PRESSURIZATION SYSTEM 1 FAILURE IT WAS PERFORMED FAULT ANALYSIS IAW TSM 21-31-00-810-801-A, REPLACED THE CPC 1 IAW AMM 21-31-34 PB401, AS A PREVENTIVE ACTION, REPLACED THE OUTFLOW VALVE IAW TSM 21-31-00-810-828-A, AND AMM 21-31-51 PB401. PERFORMED OPERATIONAL TEST IAW AMM 21-31-00-710-002 WITH NORMAL RESULT.