Just a few minor observations about the PMGD Electrical System. Not sure if these have been commented on before.1. The Standby Power Switch in PMDG only seems to have two positions, rather than three on the real 737 (very confusing). 2. Standby Power and Ground Power seem to come on when they are not supposed to: For example in the following scenario...External, APU or Engine power has not been applied (in PMDG) and the park brake is not set (BTW, are wheel chocks simulated in PMDG? :-)). I have the main battery switch off and I've just selected the Standby Power switch from the unguarded position to the guarded position (I assume this is "Auto" as on the real aircraft?). The Standby Inverter is running. Why? Shouldn't the Standby Inverter only run if the Battery is ON or the Standby Power switch is in BAT? I've been on a dead ship several times now and the Standby Switch has been in AUTO, but the Stby Inverter has not been running.From this situation, I set the parking brake (connecting the external power source into the airplane socket). The blue GND POWER AVAILABLE light illuminates. Next I select the GND POWER ON. The aircraft comes to life. I tried this last night on a real aircraft and ground power did not power the main busses. The main battery needs to be on to do this.Note: On the real aircraft, with the Battery ON and Ground Power on the main busses, if you switch off the Main Battery, the aircraft goes black (save for the GND POWER AVAILABLE light and the cockpit access light). Switching off the battery with ground power on is like switching off the battery with the APU on... The APU shuts down immediately with no cooldown period.3. On a dead ship, more likely than not, old-fashioned dial type indicators will usually read fully anti-clockwise (e.g. the fuel temperature gauge). I confirmed this last night.I've been running some PMDG tests in flight, shutting down all available sources of power whilst keeping the engines running. Oddly, I still get things like Altitude Alert, GPWS warnings, Fuel Temp indications, Bleed Air Px indications, Outflow Valve indications, cabin temp indications, engine bleed switches still operating, Master Caution & Glareshield Fault Annunciator still operating... and the Standby Power off light illuminating (I'll double check this to make sure this isn't running off the Hot Battery bus). Also, the gyro refused to topple (despite the flag being in view for half an hour). Oddly, I was unable to move the A/P disconnect bar. Also, I was unable to extend the landing gear (even though I'd imagine that the engine driven hydraulic pumps would have been providing enough power to extend them... or have I overlooked something? EDP depressurisation and shutoff valves usually need electrical power to close them). I did a quick search through the PMDG manuals, but I couldn't find any explanation for these anomalies.Thanks.Cheers.Ian.

Dang Ian, looks like you

don't blame him, he's a plane-genious(or mechanic, finetuner whatever you actually are ;))HE's supposed to find the anomalies in these things...Cheers

I do hope he will succeed in turning it into another PS1. And I don't even mind if I have to wait for the 800/900 upgrade for it to happen :-)Leo Bakker

"Dang Ian, looks like you

>>External, APU or Engine power has not been applied (in PMDG)>and the park brake is not set (BTW, are wheel chocks>simulated in PMDG? :-)). I have the main battery switch off>and I've just selected the Standby Power switch from the>unguarded position to the guarded position (I assume this is>"Auto" as on the real aircraft?). The Standby Inverter is>running. Why? Shouldn't the Standby Inverter only run if the>Battery is ON or the Standby Power switch is in BAT? I've been>on a dead ship several times now and the Standby Switch has>been in AUTO, but the Stby Inverter has not been running.Or aircraft airborne.>From this situation, I set the parking brake (connecting the>external power source into the airplane socket). The blue GND>POWER AVAILABLE light illuminates. Next I select the GND POWER>ON. The aircraft comes to life. I tried this last night on a>real aircraft and ground power did not power the main busses.>The main battery needs to be on to do this.>Note: On the real aircraft, with the Battery ON and Ground>Power on the main busses, if you switch off the Main Battery,>the aircraft goes black (save for the GND POWER AVAILABLE>light and the cockpit access light). Switching off the battery>with ground power on is like switching off the battery with>the APU on... The APU shuts down immediately with no cooldown>period.you`are right. Ship battery interlinked by the 2 small pins in ext pwr socket. >I've been running some PMDG tests in flight, shutting down all>available sources of power whilst keeping the engines running.>Oddly, I still get things like Altitude Alert, GPWS warnings,>Fuel Temp indications, Bleed Air Px indications, Outflow Valve>indications, cabin temp indications, engine bleed switches>still operating, Master Caution & Glareshield Fault>Annunciator still operating... and the Standby Power off light>illuminating (I'll double check this to make sure this isn't>running off the Hot Battery bus). Also, the gyro refused to>topple (despite the flag being in view for half an hour).>Oddly, I was unable to move the A/P disconnect bar. Also, I>was unable to extend the landing gear (even though I'd imagine>that the engine driven hydraulic pumps would have been>providing enough power to extend them... or have I overlooked>something? EDP depressurisation and shutoff valves usually>need electrical power to close them). I did a quick search>through the PMDG manuals, but I couldn't find any explanation>for these anomalies.Seems to be too much "alive". Only capt. radio and a few other items should be powered. Eng. Bleed and Hydr. shutoff are at least powered through fire handle switches - not sure if they can be operated normally as you mention. There should be no gyro flag. Not able to turn gyro off. Gear down during power off should be no problem - green lights overhead panel only ( I guess)In general it is very hard to figure out how systems work in 737NG. Very brief system description in maint.manual - guess we have to trace the system schematic = takes time.eker

"There should be no gyro flag. Not able to turn gyro off."Not sure if I follow you, Eker.... Are you talking about the PMDG sim, or the real aircraft? I've seen the gyro flag in the sim (dead ship). To not see a gyro flag on the real aircraft, it would have to be wired to the battery bus. In this case, the flag would only appear if the battery went flat or if you pulled the circuit breaker for it.Can you clarify?Thanks.Cheers.Ian.

There

Had to consult the system schematic for this one:Stby att. indicator is powered by the Stby Pwr Control Unit. Inside the unit: Bat bus relay - DC altern. relay - Battery Auto Relay - and, surprise, Hot battery relay. Just a C/B between the unit and tne indicator. Guess even a remote lighting strike is enough to power up the Control Unit (and keep flag out of view).3 flags inside indicator: Gyro - G/S and Loc. These two are controlled by the MMR 1. (Multi Mode Receiver).Only real aircraft avail to me. Just a split second (cost 40$) glimpse of PMDG 737 before shutdown to desktop. Maybe the patch will do some miracles. Anyway - what really matters: The 767PIC is still running - reliable as the old P&W JTD8 fuel to noise converters.eker

"Take a look outside and you will see the spoilers move. With no hydraulic on! :-hmmm"Don't worry, Matthias, it's not a hazard.... The strobes and beacons are still operating with the power off, so no-one is going to go near the spoilers :(Cheers.Ian.

"Had to consult the system schematic for this one:"Only one, Eker? :-)"Stby att. indicator is powered by the Stby Pwr Control Unit.Say no more ;-) ;-) ;-) The Stby Pwr Control Unit is one box I really don't want to bump into late at night. It looks like it has more logic gates and relays than Deep Thought. Still, it's always good to brush up on your Flip Flop and Exclusive OR gate logic :-) "Inside the unit: Bat bus relay - DC altern. relay - Battery Auto Relay - and, surprise, Hot battery relay. Just a C/B between the unit and tne indicator. Guess even a remote lighting strike is enough to power up the Control Unit (and keep flag out of view)."One expression I came across that I've never heard of prior to the 737 is the "Switched Hot Battery Bus". My understanding of HOT is that it is always live. The Switched Hot Battery Bus seems to need the Battery to be ON? If it has relays, I assume it's a plain ol' Battery Bus. Is there a distinction?When you say there is only a CB between the unit and the indicator, do you mean there are no Switched Hot Battery relays involved? I have some diagrams in front of me for the Standby Power Control Unit, but none for the Switched Hot and the (real) Hot Battery Busses (24-61-11)."3 flags inside indicator: Gyro - G/S and Loc. These two are controlled by the MMR 1. (Multi Mode Receiver)."Wasn't sure if the -600/-700 series had MMR's, but realised that they'd probably be needed for the TERRain System? (GPS signals)"Only real aircraft avail to me. Just a split second (cost 40$) glimpse of PMDG 737 before shutdown to desktop. "You have our sympathies.... You're missing out on all the fun. This post-release beta phase brings out the best in all us "closet" bug bounty hunters :)"Anyway - what really matters: The 767PIC is still running - reliable as the old P&W JTD8 fuel to noise converters."Good to hear.... At least you can fully test Lee's new TCAS gauge ;-)Cheers.Ian.

And if you put this in more plain english, guys?... ;-)Regards,

Hi guys,While some of these details are beyond comprehension for mere mortals, I have nevertheless ventured some experiments.I would really appreciate it if someone would try out the following scenario and see if they come up with the same results:I'm in the air with all the electrical systems working normally. Now, just to see what happens I switch off generator 2. What I get is the following: the source off light comes on, as expected, and two window heat switches trip to off (I'm not sure that the switches should actually trip, but it's true that in this scenario the window heat to these windows is off). But the interesting part is this: there are a number of warnings on the annunciator panel, like fuel and hydraulic, but there are no amber lights on the fuel or hydraulic panel!Now, in my Boeing manual there is an exact description of what should happen it this situation. For instance, the No. 2 tank forward fuel pump will be inoperative. It seems as if the annunciatior panel "knows" this, but the low pressure light itself doesn't come on. (Just remembered that the annunciator panel only shows one pump failure after recall, so it seems that this is exactly opposite to what should happen).If you switch off generator 1 what happens is similar, except that the A/T will trip to off as well. Since it is powered "downstream" of the transfer bus I don't think this should happen, unless the bus transfer switch is off.This may all be rather detailed, but since a failed generator is one of the failure scenarios it would be nice if it worked correctly :-)Leo Bakker

Not sure what you're trying to simulate here, Leo... A complete Bus failure... or loadshedding as a result of only running on one engine generator? (I assume loadshedding is a feature of the 737NG?).If talking about either, no doubt there will be variations from fleet to fleet and aircraft to aircraft. I know, for example, 767's have a lot of variations.If they haven't already done so, perhaps some time in the future, PMDG could issue an official list of which systems run off which busses... and which systems/items are affected by loadshedding. However, I recall that not even sims like PS1 model this correctly. There are a variety of circumstances/situations which trigger loadshedding... and there are a number of different types of loadshedding.Cheers.Ian.

Hi Ian,Actually I'm trying to simulate a generator failure. In both my Lufthansa and Boeing manuals there is a list of "inoperative components - loss of 1 generator". Since both lists are similar and the Boeing manual is not company specific I should think there must be some common ground here.But as I mentioned, there is also the thing with the annunciator panel lighting up with items that have no warning lights on. No matter how the electrical system is modeled, that can't be right. So I was curious if it's just me or of other people get the same.Leo Bakker