EMDP A/B OVERHEAT lights won't extinguish

[signal_runner 0]

Hi,Most amazing aircraft ever - totally mind blowing. Anyway I have a question (I've read quite a bit of the provided documentation and can't find the answer to this - so be gentle): I had service based failures on, and, in the before start procedure got a EMDP A/B OVERHEAT failure - both OVERHEAT and LOW PRESSURE lights above both the A and B EMPD switches came one and stayed on. woo hoo! Just like the real thing! Well, I elected to get the engineers to look into it rather than continue the flight (I cleared the failure via the CDU menu option under Hydraulic failures).Trouble is, even though the CDU said the failures were cleared, the warning OVERHEAT and LOW PRESSURE lights just wouldn't extinguish - with engines running and switches cycled etc. They stayed on for the rest of the flight. Hydraulic quantity % and pressure (3000) were normal according to the lower DU. Is this a bug, or is there something I missed? Thanks,signal_runner

[rsrandazzo 6,353]

Nameless- Sign your post as our forum requires, and I'll be happy to fill you in on what you are missing.

[signal_runner 0]

Very sorry Captain Randazzo - I've updated my profile display name.Many thanks for your pending reply,Tim Hollobon

[signal_runner 0]

I'm dying to find out what I was missing

[rsrandazzo 6,353]

Tim- The EMDPs are cooled using what are best described as fuel cooled heat exchangers. The temperature sensor for the EMDPs is monitoring the temperature of the case drain fluid, which reflects the source of greatest heat output on a normal pump. There are a number of events that will cause the EMDP to overheat: 1) Every time you cycle the pump from OFF to ON, it increases the pump temperature briefly. Cycling the pump off/on repeatedly without allowing adequate time to cool will cause the overheat indication. 2) Operating the EMDP without sufficient fuel in the main tanks (from memory: 1,675lbs) will also cause overheating because the fuel quantity is insufficient to provide an adequate cooling mass to the heat exchanger. 3) An internal failure of the pump might also cause the overheat light. (You can test for this by looking at the FAILURES pages, but the chances of you getting BOTH pumps to fail mechanically at the same time is so remote that you should purchase a lottery ticket if it happens to you...) To clear these failure modes, grab your QRH! The pumps will cool by normal radiative cooling over time and the rate of cooling will vary slightly with ambient temperature. It is also important to note that the heat at which the pumps will "become active again" is quite a bit lower than the heat at which they will trip the overheat- resulting in a bit of waiting until the pump has cooled sufficiently. This is modeled... In the INTRODUCTION chapter, toward the end, I put in a list of "geek facts" about the simulation that includes a half dozen or so more interesting facts about the NGX simulation of the hydraulic system. See? You just learned something pretty cool about the airplane! Fun, isn't it?!

[signal_runner 0]

Thanks very much for all that Robert - indeed the main tanks were completely empty at the time, so no cooling. I can't believe you guys modelled that.

[andysim 0]

Thanks very much for all that Robert - indeed the main tanks were completely empty at the time, so no cooling. I can't believe you guys modelled that.

its certainly modelled to a whole new level for us fligthsimmers =)

[ZachLW 37]

This is the most fun part of the simulation for me. Learning little tidbits here and there really adds up to what is a pretty thorough understanding of the systems (especially for a geek like myself).

[NoahBryant 26]

So how specifically did you fix this? I have the same issue, followed the QRH, tried to give them time to cool, but nothing worked. I forgot what i did to get them to fail, nut I think I left the elec pumps on for too long after landing. Anyway, I cleared the failure but nothing else is getting the OVERHEAT and LOW PRESSURE lights to clear. I have done a few flights now like that...pumps on, pumps off, no matter what I do it won't clear them.

[Burnspot 5]

So how specifically did you fix this? I have the same issue, followed the QRH, tried to give them time to cool, but nothing worked. I forgot what i did to get them to fail, nut I think I left the elec pumps on for too long after landing. Anyway, I cleared the failure but nothing else is getting the OVERHEAT and LOW PRESSURE lights to clear. I have done a few flights now like that...pumps on, pumps off, no matter what I do it won't clear them.

Check your fuel heat; if it's a saved flight, then there's something screwy with the fuel heat and EMDP cooling. Fuel heat is pegged high on some saved flights. No idea on how to fix that short of starting with a fresh flight.

[NoahBryant 26]

Check your fuel heat; if it's a saved flight, then there's something screwy with the fuel heat and EMDP cooling. Fuel heat is pegged high on some saved flights. No idea on how to fix that short of starting with a fresh flight.

Yeah thats what I did. Normally I prefer to keep a single save flight going as I progress through my flights, but just making a new flight fixed the issue.

[Burnspot 5]

Now that you mention it, Hotfix 3 did not appear to fix this glitch. Loaded up a saved flight tonight and had the pegged fuel temp gauge. I just loaded a new panel state to clear it up.