What was found
RETURN TO BLOCK X2 WITH L PACK INOP. LT CTC NO EXISTING FAULTS. SYS TEST FAILED AFT TRIM VLV 21-61130. REPLACED VLV, LEAK CHECK GOOD. SYS TEST AND PNEU T/E WITH APU AIR PASS. NO FAULTS ON ASCTU. DID OPS TEST ON FL CONT VLVS, ASCTU BACKUP CONTROL. ASCTU FAILED TO OPERATE B PACKS. REPLACED ASCTU PER M/M. NEW ASCTU WILL NOT OPEN FLOW CONTROL VLVS. ETOPS CATEGORY 'E': PROBLEMS WITH SYSTEMS CRITICAL TO ETOPS.