Hi Naito,Hope you are doing well! I am very sorry to trouble you. We found a question about the ACOC during maintenance. There is no indication of leakage during testing the ACOC, but there is actually oil leakage after installing on the Engine. So we perform the testing procedure (both proof pressure test and leak check) with hot oil, and we found indication of leakage at the location shown in the picture 1 (leakage is not obvious and no bubbles). We think the testing procedure may be revised to using hot oil in order to find leakage. Could you please confirm it? Besides, could you please supply the associate information to repair it?Looking forward to your reply! Have a nice day!