PMDG 737: Hydraulic Electric Pumps - Overheat

Hi,
start is in cold & dark Mode.
Full pumpsAFT FWD 1 & 2 and HYD Pumps ENG/ELEC 1&2 are activated.
In long Flights i get the Message after few hours
“Hydraulic Electric Pumps - Overheat” in ELEC1/ENG2
and the ENG2 goes after a few minutes switches off.
Pause Button and Failures Simulation are’nt activ and i have enough fuel.

Thank’s

Not sure if applicable but do you occasionally go into maintenance and perform services on systems?

One of them is hydraulics. I don’t have failures activated but I do believe that regular maintenance is still required, regardless. I service everything every 3-4 flights, whether or not it’s necessary. I’m not paying for the perishables so why not make use of them.

no kidding? I’ve flown a few flights just not consecutively (over the course of since the plane was released. I’m due for another one actually) but now i’m wondering if the simulation is actually that deep and that would actually blow me away even further with the plane.

Where can i look to see the “current state” of the plane? Now I’m gonna be paranoid on my next flight looking out for things starting to break…

I’ve installed the 737 again. Same effect. i can’t find any information for this issue.

That´s AMAZING!!
The PMDG 737 has overheating of the hydraulic pumps simulated? Awesome!
What circumstances can lead to the overheating of one hydraulic pump? Too low pressure on the other two hydraulic circuits so one pump has do move the ailerons alone?

th-1769162168

With failures off, the most boring setting in flight sim because nothing interesting ever will happen, no system should get damaged or off. It is probably a bug in the PMDG737.

I had duct overtempered,

then decided to turn off all heatings switches after landing with quick positive effect. On other side, there are temp controls and checklists to specific situations. In case of day landing on Monastir Habib with outside temp it’s quite expected.

yep. Introduction. page 42. but no todo for the resolution or i overlooked.

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This awesome PMDG 737 becomes more precious and uniqué every day!

Hydraulic fluid overheat

The electric motor-driven pumps (EMDP) and their case drain output temperatures are monitored, and when too high, respective protections activate.
Temperature sensors are located on the pump casing indicating pump hydraulic fluid overheat, and in the return case drain line from the pump to the reservoir indicating return fluid overheat.

There are two different EMDP overheat protective circuits possible, just an overheat indication or a protection that de-energizes the pump when it overheats.

OVERHEAT indication:
When A or B EMDP hydraulic pump and/or case drain temperatures exceed safe limits, the respective hydraulic amber OVERHEAT light illuminates on the hydraulic panel together with the HYD annunciator and MASTER CAUTION lights.

When the EMDP case drain hydraulic fluid temperature increases >107°C the OVERHEAT light illuminates, when temperature drops <85°C the light extinguishes.

When EMDP (pump) hydraulic fluid temperature increases >113°C, the OVERHEAT light illuminates, when the pump temperature drops <102°C – 85°C the light extinguishes.

AMM NOTE: If fuel temperature increases >32°C, monitor system A and B OVERHEAT lights.

Pump de-energizing:
When hydraulic fluid temperature in the EMDP increases >124°C, a thermal switch de-energizes the HYD PUMP relay thereby stopping the EMDP, indicated by its respective LOW PRESSURE and MASTER CAUTION lights. When the temperature drops <60°C, the relay energizes again allowing the EMDP to run when selected ON.
The OVERHEAT light does not illuminate in this case, so the overheat light only indicates on a case drain fluid overheat.

MEL Note: The OVERHEAT light may be inoperative provided the respective LOW PRESSURE light operates.

QRH Procedure: When the OVERHEAT light illuminates and the EDP pressure is >3300 PSI, select the EDP to OFF.

My approach is that the EDP has no overheat warning, so when its output is >3300 PSI it could indicate a malfunctioning EDP which affects that total system’s hydraulic fluid temperature indicated by a too high nominal output pressure and the OVERHEAT indication.

What’s Happened? What can i do?

The oil must be refilled. Ask your local aircraft shop engineer - or the PMDG FMC maintenance options :wink:

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Look at how much amber is showing. You’ve configured your fuel pumps all wrong. And probably had master cautions during the whole flight because of this. Don’t ignore amber lights.

Your center tank is full and your wings are almost empty. This means that you didn’t turn on the center fuel pumps so that center tank fuel was unused. With more than 726Kg of fuel in the center tank and the center tanks pumps off, you’ll get a fuel config alert like you can see there. You’ve also exceeded an important airplane structural limitation. If the center tank contains more than 453Kg of fuel, the wing tanks must be full. NEVER have fuel in the center tank unless the wing tanks are full. Bad bad.

If you have fuel in the center tank and in the wings tanks, you should have 6 pumps on. The center fuel pumps operate at higher pressure so the center fuel will be used first when all the pumps are on. Then, when the center tank runs out of fuel, you can turn the center fuel pumps off (when you get master caution+fuel) and the engines will continue using the fuel from the wing tanks with the 4 remaining fuel pumps.

What happened there my friend is that your right engine was starved of fuel.

Here, have an FCOM:

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In case of question what to do in flight,

i recommend one good Youtube msfs video from Insbruck with off of one engine during t/o V1. It describes also arrival with one engine and I liked also pilot’s play :slight_smile:

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Many Thanks for the Document and Information.
I will very much like to read it.

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The bottom line to your issue is probably your fuel pump configuration. Turn on pumps in every tank where you have fuel and you shouldn’t have issues like that.

Unless you’re running your APU for a long time for simulating ETOPs or something, or running on only one engine, you should have basically symmetrical fuel quantities in the wing tanks.

So for your next flight, turn the fuel pumps on for every tank you have fuel in, including the center tanks. When you get a Master Caution - Fuel, check your center tanks to confirm they’re basically empty, then turn off the center tank pumps. Continue flying on the wing tanks.

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Thanks for Reply. The Issue was the center tank pumps. :slight_smile:
I use Honeycomb yoke and Bravo Throttle Quadrant.
I turned off all the Keys, which I don’t need. New Config only for PMDG 737.
Now is the center tank Pumps on.

Yeah but more importantly, if you’re in flight and suddenly an amber MASTER CAUTION light illuminates in front of you, read the illuminated word on it (could be on the captain side or the FO side). If it says FUEL you should look at every fuel related panel in the cockpit and find the reason why the light came on. If the master caution says AIR COND you should look at the pressurization panel and so on. Then you can grab the QRH and look for the checklist usually titled with the same name as the light that came on and read through it performing the numbered steps one by one. That, plus the FCOM, is a good way to learn the airplane.

Here, have a QRH

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Thnx for your brilliant support here :wink:

Can you elaborate on this? Is it a balancing thing or just how the fuel system is supposed to work?

If the wing tanks are not full, the unused fuel in the center tank should be considered as “payload” and would count towards the Maximum Zero Fuel Weight limitation. The maximum zero fuel weight is a structural limitation of the wing. It’s basically given by how much weight you can hang from the wings inside the fuselage.

The AFM states that if there’s fuel in the center tanks and the wing tanks are not full then the sum of the zero fuel weight plus the weight of the unused fuel in the center tank could exceed the MZFW. If this happens, the AFM allows an exceedance of the MZFW of 2300Kg during take off and cruise and 1400Kg for landing.
The MZFW of the 737-700 is around 54657Kg. So the sum of the zero fuel weight plus the fuel in the center tanks whenever the wings aren’t full must be below 56975Kg for take off and cruise and below 56057Kg for landing.

This is not an issue if you follow the fuel usage guide which is simply:
-If there’s fuel in the center tank → 6 pumps on
-If there’s no fuel in the center tank → 4 pumps on

Then there’s the abnormal scenario of having fuel in the center tank and a malfunction of both center tank pumps. For that there’s a QHR Checklist called FUEL PUMP LOW PRESSURE that says among other things “Center tank fuel is unusable. Main tank fuel may not be sufficient for the planned flight”. So you’d need to run numbers to make a decision.

Sadly I cannot share with you the AFM but the QRH and FCOM that I linked are a must have for any PMDG user since Boeing revoked the permission to include these manuals with the addon purchase.

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