After reading and participating in a thread on this subject (http://forums.avsim.net/dcboard.php?az=show_mesg&forum=136&topic_id=61841&mesg_id=61841&page=2)and getting greater knowledge and insight on it all, I have some questions about the order of certain things in startup procedure. I made a checklist of my own, combining the one from the PMDG manual and Metzinger's tutorial. IMHO some things aren't very logic, so I'd like to ask you all if I'm right or wrong. Sometimes I think I will be very nitpicking (if that is the right word), but I just like to do things as realistic as possible... Here it goes (it's a long story, so be patient.... ;)1. If I start the APU immediatley after turning on the BATTERY I do not need GROUND POWER, do I?2. The YAW DAMPER is switched on quit early in the procedure. Why? It isn't needed until after the start!3. Also, the HYD PUMPS are put on quit early in the procedure. Why? As far as I can tell they aren't needed until after the engine start, when you need to set flaps, trim and use other input controls. Why not put them on after engine start? Specially the ENG HYD PUMPS, which won't work (I guess) until the engines are started... You could put on the ELECT HYD PUMPS, but still, where do you need them for at this stage? Or do you always start the ELEC and ENG PUMPS at the same time?4. FUEL PUMPS are put on quit after starting up the APU. Why not just before starting the engines? (As I understood, the APU get's fuel from the left tank automatically, without needing to put the pumps on).5. Does it matter in which order you set the AIRCO PACKS to AUTO together with the RECIRC FAN and the ISOLATION VALVE? (PACKS > ISOL > RECIRC or ISOL > RECIRC > PACKS or whatever order...) Or does the order not matter much as long as you do them all three immediatley after each other? Also, shouldn't this be one of the first things yo do after starting up the APU? Together with turning on the CABIN/UTIL and IFE/PASS, in order to get the plane ready and comfortable for your passengers... In my current list the HYD PUMPS are on earlier! And the APU BLEED is turned even earlier than that, while that one is only needed for the AIRCO...6. As soon as the ENG GEN are on I can close the APU, can't I? Now I've still got some other stuff I do in between those actions (PACKS back to AUTO, ISOL VALVE to AUTO, PROBE HEAT to ON).7. At what time are the doors for the passengers opened? Or doens't that matter at all?And now to the Shutdown procedure...1. The opposite of question 6... As soon as the APU is running (and the APU GEN's are on) I can shutoff the ENG GEN, can't I? (Although I guess it is safe to way until you are parked and ready for the Shutdown). In my current procedure the ENG GEN are left on while the APU is already running for sometime.2. Can the HYD PUMPS be shut down as soon as you are parked? Yo don't need them anymore, as far as I can tell. Also it seems logical to close the ENG HYD PUMP because the ENG GEN is already off (if I was right in question 1... ;)3. As soon as your parked AND shut off the ENG GEN, you can shut off the FUEL PUMPS, or not? You could also set the ENG START LEVERS to CUTOFF then, I think... These three things are WAY apart on my current checklist...3. I noticed in the Shutdown procedure the RECIRC FAN and ISOLATION VALVE are swichted off quit some time before switching off the PACKS. That doesn't make sense, because for the PACKS to work after the ENGINE GEN's are off, the ISOL VALVE should be OPEN (so the APU can use it for the complete system). Shouldn't it be better to close the RECIRC and ISOL at the same time with the PACKS (which is the LAST thing I do on my list before shutting down the APU)? If so, does it matter in which order...? (PACKS > ISOL > RECIRC or ISOL > RECIRC > PACKS or whatever order...)4. When do you turn off the PASSENGER SIGNS and open the DOORS? At the same time or not? And do you have to turn of some other things first, in order to keep it safe for the passengers?Last question... What actually turns off the engines...? Switching off the FUEL PUMPS? There is nog knob to turn off the engines...When I get some satisfying answers I will post my ultimate checklist on this forum (if you don't mind) for correcting AND to help other 737 newbies. ;) The list only contains things you HAVE to do: everything you only need to check isn't on it. This way it is easier for me to get everything up and running in a short time.Well, that's all (as if it wasn't enough... ;) Hope I haven't forgotten something.To everyone who made it until the end of this post: thanks for your time! :)

"1. If I start the APU immediately after turning on the BATTERY I do not need GROUND POWER, do I?"Correct, Jeroen."2. The YAW DAMPER is switched on quit early in the procedure. Why? It isn't needed until after the start!"I think the idea behind this is "flow". The initial panel scan sets up as many switches as possible.... without being a hazard to ground personnel, wasting fuel and electricity, etc."3. Also, the HYD PUMPS are put on quite early in the procedure. Why? As far as I can tell they aren't needed until after the engine start, when you need to set flaps, trim and use other input controls. Why not put them on after engine start?"Brakes need hydraulics. There is a limited amount of stopping power in the emergency brake reservoirs."Specially the ENG HYD PUMPS, which won't work (I guess) until the engines are started... "The ENG HYD PUMP switches are basically never touched. They are always selected on. Your panel scan is just confirming that they are in the correct position. This is not uncommon on many types of aircraft."4. FUEL PUMPS are put on quite after starting up the APU. Why not just before starting the engines? (As I understood, the APU get's fuel from the left tank automatically, without needing to put the pumps on)."The APU can suction feed itself, but suction feed is not very efficient. It's best to put at least one left tank pump on."5. Does it matter in which order you set the AIRCO PACKS to AUTO together with the RECIRC FAN and the ISOLATION VALVE? (PACKS > ISOL > RECIRC or ISOL > RECIRC > PACKS or whatever order...) Or does the order not matter much as long as you do them all three immediatley after each other? Also, shouldn't this be one of the first things yo do after starting up the APU? "If it is a hot day... or a very cold day, then you will need to put on the aircon as soon as possible. The temperature in the cabin may take a while to stabilize. You don't need to immediately do one thing after the other, but my personal preference is to provide air to the ducts first, then switch on the packs: After turning on one pack, I try to see how well the bleed air system handles the pneumatic load of one pack, then I turn on the second pack if it looks ok. Recirc fans will help distribute/even up the air in the cabin with or without the packs being on. On some other Boeing types however, if the packs are off, the recirc system can suck hot air from the ceiling area above the cabin roof and blow it into the cabin. "6. As soon as the ENG GEN are on I can close the APU, can't I? "It usually is turned off, but refer to recent messages on this subject... In some cases, where the runway is short and the temperature is hot, the APU can be used to run the airconditioning... allowing the engines concentrate on providing thrust for takeoff, not bleed air for aircon."And now to the Shutdown procedure...1. The opposite of question 6... As soon as the APU is running (and the APU GEN's are on) I can shutoff the ENG GEN, can't I?"Toggling the APU generator switches to on will turn off the engine generators anyway. You want the power transfer to be as smooth as possible.... that is, you shouldn't turn off engine generators (plunging the cabin into darkness) and then turn on the APU generator switches 10 minutes later. Note that there is only ONE APU generator. The two switches simply allow you to put APU generator power onto the left and right side of the aircraft (depending on what power is already on the aircraft)"2. Can the HYD PUMPS be shut down as soon as you are parked? Yo don't need them anymore, as far as I can tell. Also it seems logical to close the ENG HYD PUMP because the ENG GEN is already off (if I was right in question 1... "The ENG HYD pump switches don't need to be touched. When the engines have stopped spinning, the engine pumps will be providing no pressure.3. As soon as your parked AND shut off the ENG GEN, you can shut off the FUEL PUMPS, or not? You could also set the ENG START LEVERS to CUTOFF then, I think..."After selecting the APU generator on, the engines should be turned off using the cutoff switches. Tank fuel pumps are turned off afterwards... otherwise the engines will be suction feeding (see notes on APU above)... and still running."3. I noticed in the Shutdown procedure the RECIRC FAN and ISOLATION VALVE are swichted off quit some time before switching off the PACKS. That doesn't make sense, because for the PACKS to work after the ENGINE GEN's are off, the ISOL VALVE should be OPEN (so the APU can use it for the complete system). Shouldn't it be better to close the RECIRC and ISOL at the same time with the PACKS (which is the LAST thing I do on my list before shutting down the APU)? If so, does it matter in which order...? (PACKS > ISOL > RECIRC or ISOL > RECIRC > PACKS or whatever order...)"Recirc fans can be turned off at any time. Personally, I would turn off the packs before switching off the bleed supply. On some types of aircraft, the Recirc Fans can use up a lot of electricity, putting a lot of strain on, say an Ext Power unit. Sometimes it may be necessary to switch off the Recirc Fans to stop the external power supply automatically tripping off under excessive load."Last question... What actually turns off the engines...? Switching off the FUEL PUMPS? "The fuel cutoff levers just behind the thrust levers. Switching off the tank fuel pumps shouldn't turn off the engines. Electrical power is required to turn off the engines. If you lose electrical power from your busses, however, including the Main Battery, the 737NG has a backup battery to shut down the engines.Hope this makes sense.Cheers.Ian.

Wow! Great answer! I hardly expected such an answer to my LONG post! :)Well, first of all some things begin to dawn to me... Someone told me the PMDG standard cold and dark cockpit wasn't the way it should be: so ever since I always do the following things to get (what I though was) a real C&D cockpit: I turn the STANDBY POWER to AUTO (which is okay), but after that I always turn the ENG HYD to OFF, CLOSE the ISOL VALVE and set the RECIRC FANS to OFF! What I understand from your explanation is that there is no need for this! (I also had a habit of closing the ENG BLEEDS, but already heard that wasn't right). Okay, well, a lot had become clear now, but (of course..) it also brings up some new questions (if you or anyone else don't mind... ;) 1. So... in my C&D cockpit I can leave the ENG HYD as they are (ON) and also the ISOL VALVE and RECIRC FANS (both AUTO). I can turn the RECIRC off if I want to (as you explained) and I can set the ISOL VALVE to OPEN when I'm only running on APU (to get bleed air to the complete system). But... it seems to me I never have to touch the ISOL VALVE switch at all, because system logic opens it when only the APU is providing bleed air. Still, the PMDG checklist says I have to set it to OPEN a while before engine start. It this done just to be sure or is it really not necessary?2. When should I turn on the ELECT HYD PUMPS? The ENG HYDS only work when the engines are running, so I think I should turn the ELEC HYD on as soon as the APU is running...? Otherwise there are no HYD PUMPS until after engine start...3. Under normal circumstances I will never ever have to manually put any GEN switches to OFF, right? The GEN switches (APU and ENG) are really only needed to put the GEN's on, if I'm not mistaken: after the engine start I can set the ENG GEN to on and then turn off the APU START off which automatically turns of the APU GEN (or maybe the APU GEN is alreay stopped when I start the ENG GEN?), and during shutdown turning the APU GEN on will automatically shuts down the ENG GEN. 4. Should I first close the APU BLEED before setting the APU START to off, or doesn't that matter because turning off the APU START shuts off the APU GEN and the APU bleed automatically?5. Should I turn off the ELEC HYD before I turn off the APU or doesn't that matter also?(I asked question 4 and 5 because those switches need to be set off one time or another in order to get a real cold and dark cockpit in the end... I HAVE to switch them to off one time or another... I mean, in the end the cockpit has to look exactly the same as when I first started the flight, right?)6. At shutdown I suppose I have to turn on the APU BLEED before turning of the engines (with the CUTOFF LEVERS) otherwise there will be no bleed air for a short while (since the ENG BLEEDS are of course automatically off when the engine is off...), right?7. Is it better to turn the FUEL PUMPS off (during shutdown) AFTER turning off the APU (because you said suction feed isn't really that good)? This would mean turning off the fuel pumps would be the last thing to do before turning off the battery. (The same goes for the start: after turning on the battery Ishould turn on (at least the left) fuel pump...)Well, I hope someone still knows what I mean by it all... ;) It was pretty complicated to write this message (and it took quit some time, just like my inital post!) without asking things twice and/or looking stupid... ;)

1. It's done to make sure make sure the isolation valve is open.2. Like he said earlier, it would be best not to toutch the hydraulic pump switches. It may be a good idea to if you are the last flight of the night, but leaving them on until the next flight won't do anything.3. You can shutdown the APU after you switch to only one ENG GEN. You will only need one engine generator too provide the power you need, such as aircon, packs, etc.4. It's best to turn it on after you've switched to APU GEN5. Like he said earlier, it would be best not to touch it if it's confusing you this much.6. Yes, but make sure you turn on the APU Bleed (which both engine bleeds are on) when you aren't moving. While taxing from landing, you should turn on the APU and switch to APU GEN. It's not nessecary to turn on the APU Bleed air yet because the engines are still powered giving you the things you need.7. In real life, this is the thing you should do. But, the PMDG doesn't model APU fuel consumption anymore because of early problems with it. If you want to make it more real, turn it on before the APU. Leaving them off won't affect the APU.Nick B.Continental Airlines Virtual 737NG Pilothttp://www.precisionmanuals.com/images/forum/800driver.jpg--AMD Athlon XP 3200+ @ 2.2 Ghz (Equal to 2.8 ghz)400W Power supply3x 80 mm Case FansSoyo VIA KT600 Dragon PlusnVidia GeForce FX 5200 128 mb2 x 512 PC400100 GB Western DigitalMicrosoft Sidewinder Precision 2

"1. But... it seems to me I never have to touch the ISOL VALVE switch at all, because system logic opens it when only the APU is providing bleed air."If you have both packs on and being fed by the APU, you will have to manually put the ISO VALVE to open (if your engine bleeds are both selected on). The rule is, in AUTO, if both packs are selected to operate and both engine bleed valves are selected open (ON), the isolation valve will close. Any variation in the pack/engine bleed switches will open the isolation valve.Hope this helps.Cheers.Ian.P.S. A note on engine hydraulic pumps... Switching off an engine pump with the overhead panel switch activates an electric circuit to depressurize the engine hydraulic system. If you leave the pump off during a long ground stay, this can put a strain on the "depressurization solenoid" in this circuit. However, with a dead ship, there is no electrical power available, so, as far as I know, you shouldn't wear out the solenoid.

Well, things are almost clear now! The only thing that hasn't been answered yet is when I should turn on and turn off the ELEC HYD PUMPS (my questions about this were answered, but only by referring to the ENGINE HYD PUMPS... ;)When I get an answer about this too, I will post my Things-you-HAVE-to-do-checklist for corrections and tips. ;)

Turn them off after engine shutdownNick B.Continental Airlines Virtual 737NG Pilothttp://www.precisionmanuals.com/images/forum/800driver.jpg--AMD Athlon XP 3200+ @ 2.2 Ghz (Equal to 2.8 ghz)400W Power supply3x 80 mm Case FansSoyo VIA KT600 Dragon PlusnVidia GeForce FX 5200 128 mb2 x 512 PC400100 GB Western DigitalMicrosoft Sidewinder Precision 2