APU EGT down to 0-100 °C
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Hi all,
I have a weird behaviour of the APU on the RJ Professional and the 146, which I haven't found on the forum. I am using MSFS 2020, latest patch.
I start the APU normally. RPM and EGT increase normally. APU Gen is on. APU Air is off.
After a few minutes, sometimes more, sometimes less, the APU EGT goes down to 100-200 °C. I also had the EGT just drop instantly to 0 as if I had pressed "Stop". RPM is still 100 %.
Only if I change something with apu air on or off, one pack on or off, the EGT begins to rise again to 450 °C. But this only stands for a few minutes. Then the cycle begins again. I have no idea, what is causing this.
Also, the Cabin Temp sometimes falls to 10. This sometimes happens, if I change my view to the outside view.Has anyone else seen this behaviour?
Thanks in advance.
Best regards,
Chris
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It is expected behaviour that the APU TGT will vary depending on load. The APU has more load when the APU AIR/PACKS are ON, so EGT will increase.
When the APU switch is set to OFF, it is expected behaviour for the APU RPM and TGT needles to instantly drop to 0 in early examples of the 146 (as we have simulated). This is due to power being removed from the APU ECU, which also removes power from the APU instruments (something which an ECU mod changed on later 146/RJ examples).
The cabin temperature in the 146 is simulated to be affected by a variety of factors, including air supply, temperature selection on the Air Conditioning panels, passenger/service door position, and if the aircraft is in direct sunlight. If the aircraft's doors are open in cold weather, the cabin temperature will decrease.
We're not aware of any issues with the APU remaining at 100% after APU shutdown, and we haven't seen any reports of APU EGTs as low as 100/200℃. However, if this is something that is repeatable behaviour, could I kindly ask you to open a ticket with Just Flight Support via the following link: https://www.justflight.com/support
In the ticket, if you are able to provide steps for how to reproduce this behaviour, including the steps taken to set up the aircraft in the state in which this behaviour occurs, as well as the weather at the time, then our support team will be in the best position to assist with further troubleshooting, or pass this information over to the development team if required.
Mark - Just Flight
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Hi Mark,
thank you for your reply.
I just tested for about 2 hours. It seems, that GSX might be responsible as I was only able to reproduce this, when I was boarding the plane via GSX. If the APU is running the EGT spikes from 400 to 600 almost as soon as the first passenger visibly boards the plane. From there it jumps around a few times. This stops when the APU EGT goes down to about 100-200°. Then only a change in the APU load restores the correct EGT. It doesn't matter, if the APU Air/packs/recirculation/grnd air/ground electric/ is on or not. It is reproducable every time.
Also I was able to also induce these spikes while boarding with GSX, when pressing F1 to get to the outside view, press right mouse button to move the view around and then press F1 again. Then the EGT also goes crazy. I made a video of this. But this can only be done, when the first passenger has boarded.When I wasn't using GSX, everything was ok and as expected.
So now I'm wondering, how GSX could have an influence on the APU EGT and if this issue can be solved without the GSX team.
@Mark Should I still open a ticket with Just Flight Support?
Thanks in advance.
Best regards,
Chris
