What was found
AFTER ENGINE START AND PACKS RUNNING, AUTO FAIL LIGHT ILLUMINATED. THE LIGHT EXTINGUISHED WHEN ALTERNATE MODE SELECTED. ACFT GROUNDED. PERFORMED A NR 1 AND 2 PRESSURE CONTROLLER BITE IAW FIM 21-31-00. FOUND AUTO FAIL ON. PLACED SWITCH TO MANUAL. FAULT LIGHT WENT AWAY. NR 2 CONTROLLER FOUND PREVIOUS FAULT. CONTROLLER FAILED. CLEARED FAULT AND PERFORMED A NR 2 CONTROLLER, OPS CHECKED SYSTEM IAW AMM 21-31-00. SYSTEM CHECKED NORMAL. FOUND LOOSE MATERIAL ON OUTFLOW VALVE, PERFORMED FIM 21-31, TASK 824. NR 1 AND 2 CONTROLLERS BITE NORMAL, NO CURRENT FAULTS IAW FIM 21-31, TASK 801. GROUND VERIFICATION SUCCESSFUL.