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Guest dlrk

Fuel temperature-this is extremely frustrating

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Guest dlrk

When I load the aircraft, the fuel temperature is off-scale and the hydraulics are overheated. I've looked in the panel state.savs, and the temperature looks normal. The fuel temp will only normalize if I start it from cold and dark. Any fix possible?

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It's a bug, hopefully fixed in SP1. Search the forums, it's been discussed quite alot before on here.Just set the default panel state load to be Cold and Dark or another one of the panel states.


Tyler St. Peter

 

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Quote from RSR

Gents- One user-habit that we would like to break is: "I see a fault/failure that I didn't set, therefor it must be a bug in PMDG's software." To correct the original poster: Overtemp lights don't "just happen." They are triggered by causes, nearly all of which you can avoid with just a little bit of system knowledge... It has been awhile since I posted this, so here goes: First: Open your FCOM Vol2 to HYDRAULICS Pg. 13.20.3: You will not here that it warns you that you must have at a minimum 1,675lbs of fuel in each main tank in order to provide sufficient cooling to the fuel-cooled heat exchangers. When we have investigated users having a problem with overtemps, this is the #1 "ooops... I didn't realize that" item that we see for this type of report. It is worth noting that warm fuel is a possible cause if you are down near the minimum fuel quantity- although this is highly unlikely- it IS possible that your fuel temperature is insufficient to provide the required amount of heat removal through the fuel/hydraulic heat exchanger, thus causing a reduction in your available hydraulic EMDP case cooling. Next: Open the INTRODUCTION document to page 121/122. Take a read through the facts listed here on regarding the hydraulic pumps- it is educational and will give you a better idea what you are seeing. Now- some background that your books don't cover: Every time you cycle an EMDP on, the pump's output fluid temperature is going to jump around 20-25 degrees. This temperature spike comes about due to all the high velocity parts that start spinning, plus the fact that when the pump is not moving you are not getting cold hydraulic fluid to the pump, so upon startup the temperature of the entire unit jumps. The cooling of the pump will take about 5 minutes if the pump is on, and about 30 minutes if it is off. This seems counter-intuitive, no? The reason is quite simple: When the pump is running, you are getting fresh, cold hydraulic fluid to the case for cooling, hence the temperature comes down more quickly. If the pump is static, there is no cool fluid flow, this it takes longer. Neat eh? Okay- so if you cycle the EMDP's off/on a bunch of times- you WILL get a fluid overheat. If you do this until the temperature cutout sensors trip- you will notice that the OVERHEAT lights will go out, but you still have to wait around for awhile before the pump will become active again. The reason for this is explained on page 122... But once again- some pretty cool (or hot) detail for you. Now- one other thing we have seen with some users: If you have a flight state that was created with a stored EMDP failure, stored EMDP overheat, or if the flight was saved after the EMDP had been cycled a few times- you have some latent heat that is being tracked by the simulation... Over time the chance of an EMPD overheat will become more remote because the pump will cool... If you get an OVERHEAT light after loading the simulation and none of the obvious causes appear to be the trigger- this might be your issue... Hope this helps you guys appreciate the details!

Paul Deemer

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Guest dlrk

Paul, RSR's answer though is not relevant. The issue here is that the aircraft loads with a high fuel temp for no reason at all.

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When I load the aircraft, the fuel temperature is off-scale and the hydraulics are overheated.
Paul, RSR's answer though is not relevant. The issue here is that the aircraft loads with a high fuel temp for no reason at all.
Read the whole Quote and yes it is revelant, I have had the same issue happen to me. The way I fix it, is clear all the failures then reboot computer and load up a stock NGX Panel State. The Problem usually happens when people are reloading a saved panel state / flight that already has the failure encoded into it. Do not reload the saved panel state / flight that has the failure already in there or it will keep coming back every single time. If you want to have a custom panel state fix the problem first doing what I outlined above and then save a new custom panel state. In my case about 70 percent of the time when I am flying and crash in the middle of a flight and then reload the FSUIPC autosaved flight the same failure happens to me. Hopefully it will be fixed in SP1.
The fuel temp will only normalize if I start it from cold and dark
This is from the end of RSR Quote.
Now- one other thing we have seen with some users: If you have a flight state that was created with a stored EMDP failure, stored EMDP overheat, or if the flight was saved after the EMDP had been cycled a few times- you have some latent heat that is being tracked by the simulation... Over time the chance of an EMPD overheat will become more remote because the pump will cool... If you get an OVERHEAT light after loading the simulation and none of the obvious causes appear to be the trigger- this might be your issue...

Paul Deemer

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Guest dlrk

Paul, I said in my initial post that this is occurring even when I load a state I have confirmed does not contain a fuel overheat or any other failure

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In your post you said your problem went away when you loaded the cold and dark panel state? What about the other two panel states Long and Short? Do they both work as well?

fuel temperature is off-scale and the hydraulics are overheated
Even if you have failures off and none are showing this problem can still happen by reloading a saved flight or custom panel state. If all the stock NGX panel states (Short, Long, Cold and Dark) work fine and you have failures disabled then that means your loading a custom flight with failure or bug already encoded in it. Just because you do not see a failure active in the FMC does not mean the bug is not there. So the solution until they fix the glitch is to use one of the stock NGX Panel States for each of your flights. If by some chance this is happening with one of the NGX Default Panel states as soon as you load it up and have not done anything with the aircraft then you probably have corrupted Panel States and maybe reinstalling the NGX would help. 99 percent of the time this happens its because of what RSR said in the quote above, or somebody is reloading a flight and the bug kicks in and if this happens sometimes you will not even see a failure active.

Paul Deemer

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It is a bug. Open up the panel state you're trying to load with notepad in PMDG/737NGX/panelstate and change the fuel temperature to 1647, which is around 20*C.


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