APU Overheats When Shutdown

[Ramjett 27]

Col Scott,My apologies if this issue has already been discussed. Using the Forum search engine found lot's of hits, but nothing that seemed specific to the TM.I like to start from cold and dark to add to the realism when I fly the 732. It seems here lately that after I get engines running, packs set, and bleed air properly configured that when it comes time to turn off the APU it immediately goes into the red and overheats and I get a yellow "Overheat" warning on the panel. I never get a fire warning, but the APU stays in an overheat condition until I land and turn the APU back on while taxiing to the gate.A brief synopsis of my "cold/dark" process, which by no means includes everything I do on the checklist is:Gnd Call for airCall for external power(Seems like at this point the APU is already running, even though I have not started it, but temps are normal)Switch to external powerSet the aircraft up for flightTurn off packsOpen the isolation valveEngine Bleed is already on, so switch APU Bleed to on.Start enginesTurn off APU BleedTurn Packs onLeave engine bleed onNumber 1 hydraulics on (number 2 is already on)Isolation switch to AutoGasper onCall for Ground Air disconnectTurn on 1 and 2 generatorsCall for external power disconnectTurn APU offBefore I can even taxi to the runway the APU Overheat light is on and nothing I do short of restarting the APU will cause it to go out or the temp to fall back into the green.I must be forgetting something, but I follow the checklist item by item and don't see where I am screwing up.Randy

[investdude 0]

Ramjett,The APU overspeed light is the only APU light that is not disarmed when the APU switch is turned off. So if it comes on on a normal APU shutdown it simply means you have lost overspeed protection. This is on the real aircraft, I presume it is the same for the mouse.Having said that, from your description of your cold and dark procedures, it sounds as though you have not started the APU. The checklist you are using is leading you astray. You should not be asking for air, only external power. But even without external power, all you have to do is turn on the battery switch and start the APU. Once it is running put the APU generator on line on busses 2 and one. Then open APU bleed valve. When you are ready to start the engines, packs off, do not open isolation valve, leave in auto. After engines are started, turn off APU bleed valve, put engine generators on line, buses 1 and 2. Allow APU to cool down for one minute then APU switch off. APU will shut down and you should not get any APU lights on unless there is a fault.InvestdudeRetired 737-200 Captain

[Bob Scott 7,782]

Randy; If you want cold and dark at startup, make sure to set InitWithAPU_Elec to 0 in the tm.ini file (in your root FSX directory). Otherwise the panel loads with the APU running and the generators powering the busses. Never turn APU bleed air on with another source of air connected--especially with a ground air cart connected. The high back pressure will damage the bleed load and control valve. The one exception to the rule is when starting with the APU--you can leave the bleed air on with the engine bleeds open, but you must close the APU bleed valve before the throttles are moved out of idle. The "Dual Bleed" light on the OHP warns you of that.

[Ramjett 27]

Perfect,Thank you both for your help. As always, I am in awe at the level of realism in the Tinmouse, but the one thing I have never figured out is why is it called the "Tinmouse"? An inside reference only B732 drivers will get?Loading up the TM right now to see how I do with this new bit of "wisdom".Randy