Hydraulics Elec 1 + 2 overheat / low pressure

[Timberleaf 1]

I have apparently hit something in the setup menus on the FMC that is now causing me to have this simultaneous failure occur with relative persistence. How do I stop this dual-failure from continually occurring on nearly every flight?

 

* I don't save nor reuse flights

* I don't know what I have changed to cause this, but this is a recent event

* I don't have failures turned on

* It is consistent, the only failure that is occurring, both Hydraulics Elec 1 + 2, overheat/low pressure

* This is always on the ground while setting up for a takeoff

* This will NOT reset within the failures menu

* I use Active Sky 2016 (live weather)

 

Any thoughts / ideas? I have used the PMDG 737 NGX for quite a while. This has never happened until now. I expect it is something I have done.

[BrianW 124]

How low are you letting the fuel level get?

 

From the FCOM:

 

Minimum fuel for ground operation of electric motor-drivenpumps is 760 kgs/1675 lbs in the related main tank.

[Budbud 227]

Hi,

 

Do you fly in hot weather? It can happen in particularly hot temperatures you may face like in Middle East countries where the temperature can easely go over 40°C.

[docdon 4]

I'm not trying to hijack this post, but I have been getting the same thing.  I just noticed it recently.  I generally fly out of Denver, CO.  That is where I first noticed it.  I'll be watching this post for results. Incidentally, it's the Hydraulics that I'm talking about and not the fuel.

[Budbud 227]

 

 

it's the Hydraulics that I'm talking about and not the fuel.

 

There is a heat exchanger between oil and fuel. Oil is cooled down by fuel and fuel is heated up by oil to prevent freezing in flight. If you have not enough fuel, then the oil cannot be cooled down.

[docdon 4]

Ok.  I shudda known.  Thanx for the clarification.  Works just like my old 18 wheeler.

 

[Timberleaf 1]

Simply, I fly from Orlando - FL, a lot. All cases, this is where I was taking off. It has been hot, but around 35° - 37°C (95°-98°F) approximately (actual temps). In all cases this has occurred, I set the fuel to 1/3 full fuel tanks from the FMC (relative to the distance of flight).

 

Since this is a recent eventuality, and the only recent change is the addon Active Sky 2016, I have no idea what the cause is. I have used Active Sky Next for years, and this has not occurred. Not casting stones, just the only thing that has changed. I am unsure that AS16 would be the cause.

 

Also, I noted (because I am brainstorming) that at least once I had a prolonged tarmac delay. Would sitting on the tarmac cause this Hydraulic A/B overheat?

 

I have read other posts from the past (regarding this same issue) that it could be a fault saved from flight to flight. Since I don't save any of my flights, I don't see how this could be it. I DID look into the Default, CLDDRK, LONG and SHORT.sav files under the "fuel temp" section. All of them have a value of "10013".

[pcubine 143]

 

 

Any thoughts / ideas?

I have had it happen several times and it causes no problems. Just click on the caution light so it goes out and continue on. The longest I have ever flown like that is about 5 hours from KJFK-KLAX. Both  systems went a 17000 ft. into the climb to FL360.

[downscc 1,327]

Per the QRH, the pump should be turned off. The overheat could be cause by an electrical fault rather than heat transfer issues and not turning the pump off exposes you to potential fire.  The QRH specifically notes that only one pump is sufficient for operation.

 

And not mentioned, make sure your hydraulic levels are okay... they do decrease with time in the NGX.

[pcubine 143]

Dan

 

By the time I found that in the QRH and read the corrective steps, if it was anything serious I would have already bought the farm. Drive on, it don't mean nothin'.

[Spin737 102]

Wasn't this a bug from waaay back when?

[Timberleaf 1]

I can't say whether it was a bug from the early days. If it is, for what ever reason, it is being triggered by something now, that for the longest time, has not - ever (for me).

 

BOTH hydraulics A and B are overheating, and appear so in the FMC failures section. Yes, I followed the QRH for what I interpreted was a failure and found I had to turn both switches off, leaving me with little control of the airplane. The question isn't what to do when it happens. The question is WHY does it keep happening when it hasn't up-until-now. If it IS a bug, nothing has triggered it for me until now (years).

 

I have searched other posts for an answer to this. But, have found nothing, hence the posting now.

[downscc 1,327]

 

 

leaving me with little control of the airplane.

If you are turning off the electric pumps, you should still have sufficient hydro from the engine driven pumps.

 

 

WHY does it keep happening when it hasn't up-until-now.

Turn on the MFD SYS status display and have a look at hydro fluid levels, you didn't mention if you've done this although I eluded to it earlier. Levels should be above 76% when shut down and pressure should be 3000 psi.

[Patco Lch 1,465]

Strange it should happen to several people at once. Two days ago I flew from KCLT-KMDW and had the same experience during climb.[ Also using AS2016 as a side note.] I started at the runway, engines running while logging the FMC and prepping the flight  so I was on the tarmac a while on a hot afternoon. By the time I was taxing to gate at destination I was down to one hydraulic pump.

My only theory was that I have been having a time trying to configure my brake pedals. I was wondering if the pedals spiking was was keeping pressure in the hydrailic line causing heat to build.

Vic G