Dear colleagues I would like to thank you all for your valuable advice . The SIM was OK and the instructor wanted to shut down the APU after we finished the ENG severe damage NNC and the After Take off Normal CL. But as flyhardmo wrote above its not as easy as its looks. Yes we have a lot of redundancy on B777 but it depends where we are , how long we have fly to our destination, items affecting our problem and of course we can check the operation of APU from the Lower Display Unit (EGT,RPM,OIL TEMP,OIL PRESS,OIL QTY) so any time we know what is going on . I am not saying to leave it open or close it immediately but I am saying to think very carefully our action. Best regards and always safe flights to everyone .