Air conditoning "allows the cabin to be cooled before the engine is running"
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Hello everybody, I bought the TBM850 recently and have been going over the manual and cockpit. Something that's puzzling me is the behavior of the air conditioning.
The Blacksquare manual says:
The air conditioning system (also known as the vapor cycle cooling system), is driven by an electric motor, as opposed to many aircraft where it is driven directly from the engine. This allows the cabin to be cooled before the engine is running. When the compressor motor is running, the compressor will indicate with green on this visualizer, and the impeller will begin to rotate. (Emphasis mine)This doesn't appear to work -- the cabin isn't cooled (aside from the fan effect, same as FAN ONLY) unless the engine is on and bleed air is on.
But...the Cabin visualizer page on the EFB does show the compressor lit up green as active when on external power with the engine off (or with the engine on but bleed air off), which sounds like it matches the manual description.
Are the manual and EFB showing an electric compressor but the temperature simulating an engine-driven compressor?
EDIT: Continuing to look into this, I'm starting to think it's because of needing the cooling turbine to move the air, but in that case, is the manual incorrect or perhaps incomplete? i.e. is using the electric compressor to cool the cabin without the engine possible in real life but only with additional external equipment that circulates the air or something of that nature?
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@Magenta-Line said in Air conditoning "allows the cabin to be cooled before the engine is running":
the temperature simulating an engine-driven compressor
In so many words, this is what happened. The AC should be able to cool the cabin to a lessor extent when the cooling turbine is not operating. I just neglected that in the code, so it was all or nothing. I've fixed it now, and it will be in the next update.
One additional caveat that I was reminded of while reading the aircraft's POH: The air conditioning system will only operate when the engine is not running when the source selector switch is in the GPU position.
Thanks for letting me know, and thanks for engaging with all the small details in my aircraft! That's what I built them for, so it delights me to see my users take interest in all the systems they have to offer.
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@Black-Square said in Air conditoning "allows the cabin to be cooled before the engine is running":
The air conditioning system will only operate when the engine is not running when the source selector switch is in the GPU position.
Yeah that aspect seems to work perfectly, or at least the Cabin page shows it working that way: with the engine off, the compressor only turns green if the source is GPU.
it will be in the next update.
Nice!
thanks for engaging with all the small details in my aircraft! That's what I built them for, so it delights me to see my users take interest in all the systems they have to offer.
I'm new to turboprops and it's fun learning the details in this one!
I ended up with another question after that one; maybe I should make another thread since it's not related to air conditioning, but I'll go ahead and ask:
If I have the fuel tank selector switched to OFF and turn on the Aux Boost Pump, the fuel pressure gauge stays at zero like I'd expect, but the FUEL PRESS annunciator still goes out on the annunciator panel, so it looks like this:
It seemed odd but I have little clue about the real plane so figured I'd ask if that's how it's supposed to work.(This happened after I followed the shut down checklist and then later, without exiting the flight to the MSFS menu, started the engine start procedure again, so the fuel tank selector was still "OFF" from the shutdown. It wouldn't usually come up because the plane starts with the left tank selected if I start a new flight.)
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I see how that bug got in there too. Both of these were from the TBM's major update. I added thousands of lines of code, and I didn't send the aircraft to my usual beta testers before the update, which I only allowed myself to do because the TBM was the only aircraft I anticipated giving such a major upgrade. Given that you are the first one to report either of these, I would say that my effort was not entirely misplaced, but I still regret having any bugs in my software. That speaks volumes to how well you are understanding the systems for someone just learning turboprops, though! Thank you for letting me know about this too. I've already fixed it, as well. The fuel pump will also respond accordingly now by not cycling on and off when there is no fuel supply.
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Interesting read! Any idea as to when we'll get this update for the TBM?
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It will be the MSFS 2024 compatibility update, which I hope to get out in the next couple of weeks.
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@Black-Square said in Air conditoning "allows the cabin to be cooled before the engine is running":
I've already fixed it, as well. The fuel pump will also respond accordingly now by not cycling on and off when there is no fuel supply.
Nice!
@Black-Square said in Air conditoning "allows the cabin to be cooled before the engine is running":
MSFS 2024 compatibility update
Man, MSFS really dumped a load of work on you guys (3rd-party devs in general I mean) with the 2024 compatibility problems with 2020 planes.
Before getting the TBM, the main plane I'd been flying for months is A2A's Comanche, and FS2024 messes with its ability to restore the saved cockpit state, so I figure it's probably done similar things to the TBM850.
