EMDP overheat bug

[Guest dlrk]

I was attempting to start a flight from KFNT to KJFK and was setting up the overhead panel when I noticed that the overheat light was illuminated on both electric hydraulic pumps. Upon checking the FMS menu, I discovered that EMDP A and B overheat failures were active. There was no reason for this, a failure had not occurred on the last flight, nor had I done anything to trigger this. After I cleared the failure in the FMS, the problem persisted, despite no active failures being displayed. I tried activating and clearing the failures with no success. I have service-based failures enabled, however I doubt this is normal failure simulation. On previous flights, brake failures have been activated for no reason at the beginning of the flight as well. Win 7, AMD Phenom II 550 @ 3.16 gigs ramGeforce 560 Ti This resolved upon resetting my panel state, however was very annoying since I had to redo the preflight. This is the 3rd bug I've encountered with NGX where a failure is triggered for no reason and won't clear properly, the others being the brake failure and the ASX-induced wheel well fires.

[Guest dlrk]

Bump.

[Qatsimo 7]

Exactly the same thing here today. Only restart with default C&D panel state made it go away.

[RYR738 9]

I have not had anything like that so far but if it is a bug I'm sure PMDG are aware of it by now. I hope you are enjoying the NGX as much as I am ! Fred.

[willywonka 36]

What was the fuel temp at the time?

[Qatsimo 7]

Didn't took notice of fuel temp. Odd thing, it was overheated already before even switching the battery's on. Nevertheless, i enjoyed it big time :) FsPax had to unboard and wait in the lobby until the problem was solved.

[rsrandazzo 6,353]

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!

[kjjj11223344 48]

Gents-

Wow, my jaw dropped as I read this. It is incredible that the NGX has so much detail.

[wreck1463 0]

I've had this same issue...seems to happen if i "load" a flight at FSX startup, rather than create a new free flight. Seems EVERY time I load a flight I get the overheat lights. I'll try turning the electric pumps off before shutdown. Maybe that will help? Edit:The Fuel Temp is pegged full hot when I get this error. SO, any idea why I'm getting hot fuel after loading a flight? Guess the Hyd problem is an indirect issue for some of us, possibly caused by hot fuel. Edit 2:Seems a few others figured this out before me. So it's definately an issue with fuel temp being pegged hot when loading flights rather than creating flights. At least there's an easy workaround of loading cold and dark panel state. I'm enjoying the heck out of this airplane!

Edited September 7, 2011 by wreck1463

[Hans_Peter_Burwig 0]

.... Okay- so if you cycle the EMDP's off/on a bunch of times- you WILL get a fluid overheat.Very interesting details ... i´ll test it. Cool :) Thank´s Robert.Best regardsHans-Peter

[Dashik 0]

I'm loving the aircraft and the simulation of systems so this is not a moan So as I have the fault with the Overheat and Low pressure on Elec 1 and 2 lights illuminated and a fuel temp about to spontaneously combust I read through the manuals again as discussed by Robert . I've left the elec 2 and 1 switches in both on and off state for a period of time(around 45 mins each state) at 36000 feet with an oat of -23c so why is the fuel temp not decreasing? I'm currently mid way between LCLK and EGKK so I would have thought plenty of time for the fuel to cool. I'd just like to know how to fix it as I can't find an answer in the manuals. There does not seem to be a Fuel Overheat section! As I have decided to have some fun with the service based failures I've been saving my flight when I finish shutdown at the gate and then when I start my next flight I reload the saved flight and adjust the time and maybe location for the next flight so as to have some continuity for the service failures, if you follow. If I reload the default NGX CLDDRK cold and dark panel state to clear the fault does that reset my service failures? But that's not really a solution to the Fuel Overheat more of a workaround. Is it the case I can just fly the aircraft and the temp will come down eventually? Should refueling with cold fuel not adjust the temp ;) Cheers Really enjoying flying again with this 737 Regards

[Cristi_Neagu 134]

As I have decided to have some fun with the service based failures I've been saving my flight when I finish shutdown at the gate and then when I start my next flight I reload the saved flight and adjust the time and maybe location for the next flight so as to have some continuity for the service failures, if you follow. If I reload the default NGX CLDDRK cold and dark panel state to clear the fault does that reset my service failures? But that's not really a solution to the Fuel Overheat more of a workaround. Is it the case I can just fly the aircraft and the temp will come down eventually? Should refueling with cold fuel not adjust the temp ;)

As far as I know, failures get saved with the livery, so if you have an active failure, it should be there next time you load the plane up. You could test this by setting up a failure, exiting the sim, loading it again, and see if it's still there.

[victorlima01 4]

I love how everytime someone thinks there is a bug with theiy airplane someone from Precision Manuals chimes in and says: "well yeah, if you consider this behavior to be a bug, then so do real pilots. And so does Boeing." This simulation is so precise that even simers who take things seriously (like most of us here) will occasionally trip and have a hard time figuring things out. You wanted it as it real as it gets, guys. Well, you got it.

[Dashik 0]

As far as I know, failures get saved with the livery, so if you have an active failure, it should be there next time you load the plane up. You could test this by setting up a failure, exiting the sim, loading it again, and see if it's still there.

Good point Ill try that :D So all i have to do is just fly the particular livery and every time I fly I can just select the aircraft from the selection screen or just load the flight I saved and the service state etc is loaded automatically with the particular airframe yes? That's impressive :D Still need a way to cool the fuel without loading cold and dark panel state if anyone has an answer please :D

[Cristi_Neagu 134]

So all i have to do is just fly the particular livery and every time I fly I can just select the aircraft from the selection screen or just load the flight I saved and the service state etc is loaded automatically with the particular airframe yes?

For each livery, the NGX saves the state of almost 200 service failures. So that's the way it should work.