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VPA481

Brake temp

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Hi, I've noticed several times something about brake temp, that either is normal behaviour that I don't understand, or a minor bug. When landing, even with auto brake set to max (carbon or steel), the brake temperature does not increase immediatly when breaking. It's still at zero until vacating the runway. If I did read well the explanation in this forum, 0 means that the temperature is at a normal operating temp. While taxiing, the value increases above zero (sometimes 3 or 4+), so the question is: why does the brake temp increases while taxiing, as the strongest use of brake is over for minutes ? NOTA: I use NGX without any hotfix, as it's working like a charm, and waiting for SP1. Cheers for your explanation.

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Emmanuel, I believe this is because the temperature sensors haven't yet caught up to the actual brake temperatures. The brakes themselves will become really hot and if you attempt to takeoff and retract the gear after using max autobrakes and a decent load, then you will get a wheel well fire warning.

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Hi Erik, Sure, but why is the temp increase so slow or why would the sensors be so slow to measure the temp ? That is strange to me ...

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Hi Erik, Sure, but why is the temp increase so slow or why would the sensors be so slow to measure the temp ? That is strange to me ...
I don't really know why, exactly. If I knew how the temperature sensor system worked, I would tell you. As far as I know, this goes back to the PMDG MD-11, if I recall correctly. It can take minutes for the sensor temperature to reach the actual brake temps. If you do however perform a really short and heavy landing, then be advised to NOT wait 10 minutes before the sensors indicate a 9+... As you brakes/tires may already be on fire. laugh.png

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LOL.gif Well I should then consider that temp really takes time to spread ... Cheers,

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Manu, this is what it is written in the FCTM :

The optional brake temperature monitoring system may be used for additionalflight crew guidance in assessing brake energy absorption. This system indicatesa stabilized value approximately fifteen minutes after brake energy absorption.Therefore, an immediate or reliable indication of tire or hydraulic fluid fire, wheelbearing problems, or wheel fracture is not available. The brake temperaturemonitor readings may vary between brakes during normal braking operations.

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It takes time for the heat to transfer evenly through the brake pads and to the sensor.

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Manu, this is what it is written in the FCTM :
im%20Not%20Worthy.gif Thanks for this Stephane, now all is clear in my noob mind. The NGX still got a major problem: a day only got 24 hours, so may PMDG evaluate a 70 hour day + explain to my boss that he still pays me but he lets me fly this beauty all day long ?

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The NGX still got a major problem: a day only got 24 hours, so may PMDG evaluate a 70 hour day + explain to my boss that he still pays me but he lets me fly this beauty all day long ?
Hopefully in the service pack *hopes*

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LOL.gif Set options: Day 24 hrs / 48 hrs / 70 hrs Job: full time / half time / paid to fly NGX

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The only "problem" I have with the brakeheat simulation is that is doesn't seem to cool down on the ground. E.g. when the brakes temps are indicating 2.9 it will stay at 2.9 for hours. Even with a outside temperature of just 20 degrees celcius. When taking off again it will cool down eventually. Anyone else have noticed this? Kind regards, Daniel Verhaal

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Hi Daniel, The subject of brake not cooling on ground has been reported in several posts here. Make a quick search and you will find.

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Hi Emmanuel, Sorry, I only can find some posts about some heat "problems" occuring after take off. Can you tell me if this "ground" issue is really an issue or something else? Regards, Daniel

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Hi Emmanuel, Sorry, I only can find some posts about some heat "problems" occuring after take off. Can you tell me if this "ground" issue is really an issue or something else? Regards, Daniel
there was one thread directing this directly but went down really fast since no one was interestet,and 2-3 regular brake temp issues posts which some people wrote in threads where temp isn't going up ... and then a few asked in there why the temp is not going down on ground but air (offtopic) and a few confirmed it, like in this thread ...but a ticket was already written and pmdg should know about it ... but its another thing if they can replicate it, because only maybe 5-8 people are having this problem and its hard to locate for pmdg ...if they can replicate it they will fix it, if not deal with it :)

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i can confirm no brake cooling on the ground. I tried to use the brake cooling tables inside the qrh after a rejected to test and the brakes temp remained high even after an hour (should be decreasing in my case at around 18 min)christopher volle

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LOL.gif Set options: Day 24 hrs / 48 hrs / 70 hrs Job: full time / half time / paid to fly NGX
I'll take the "paid to fly NGX" option.

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