What was found
APU DID NOT MAKE 21 PSI FOR ENGINE START.(<P>TRANSFER TO MDDR 115491 IAW MEL 49-11-01A CAT C DUE 08AUG19.</P><P>LP 1097989 - M4: PERFORMED APU ECU BITE PROCEDURE IAW B767 AMM 49-61-05. DISCOVERED "APU CONTROL UNIT" FAULTS IN RECENT FAULT HISTORY. SUSPECT BAD APU ECU. DMI #115491 REMAINS OPEN.</P><P>LP 1097990 - M1: REMOVED AND REPLACED APU ECU IAW AMM 49-61-05. DID NOT FIX FAULT. DMI #115491 REMAINS OPEN. OFF PART (P/N: 2117342-20, S/N: 59-B0129)</P><P>LP 0994610 - M2: TROUBLESHOT APU BLEED FAULT IAW FIM 36-10 FAULT TREE 840. AS PER FIM, SUSPECTED FAULTY RIGHT ENG START VALVE. R&R RIGHT ENG START VALVE IAW AMM 80-11-02. NO FIX. THIS DOES NOT CLEAR DMI 115491. DMI REMAINS OPEN.</P><P>LP 0994615 - M7: REMOVED AND REPLACED RH PNEUMATIC ISOLATION VALVE, LEAK CHECK OK IAW B767 AMM 36-11-04. REMOVED AND REPLACED APU SURGE VALVE, LEAK CHECK AND OPS CHECK GOOD PER AMM 49-53-01. THIS CLEARS DMI 115491, PLACARD REMOVED.</P><P><BR /></P><P>APU SURGE VALVE OFF PART (PN: 979806-12, SN: P-690C) </P><P>NOTE: ACCOMPLISHED DURING A-CHECK (MIA), REFERENCE NRC: 00012</P>)