What was found
ON TAKEOFF AUTO PRESS FAILED. PRESSURE CONTROL WINDOWS HAD FAILED TO SWITCH TO ALTN MODE. DID AIR RETURN IN MANUAL MODE. T/S SYS PER TASK 21-31-00-810-803 FIM MANUAL. FOUND FAULT IN NR 1 AND NR 2 PRESSURE CONTROLLERS CODE 57 (CONTROL PANEL FAIL). REMOVED AND REPLACED OVERHEAD CONT PANEL MODULE PER AMM 21-31-02 AND PERFORMED TEST TASK GRND & MANUAL TESTS. OP'S NORMAL. ROTABLE PARTS CHANGE WAS INDICATED - TT # 1462217 SN OFF 07464 PANEL, PRESS, C OFF 29-2131-9-0006 7464 ON 29-2131-9-0006 0176.