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  1. Username Protected
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       #1  

    Cold cabin in flight

    Flying back to KBZN yesterday at FL380, the cockpit was much colder than usual. I was flying alone in a short-sleeve shirt (coming out of KPHX) so I bumped up the cockpit heat a bit, with no effect. I pulled up the ECS synoptics page and noticed that the temp was only 57 in the cockpit. I kept playing with the controls, digging through the QRH and the AFM looking for info, and could find nothing. Meanwhile, the cabin temp dropped to 45 and I still had an hour to go. I had been avoiding flipping the Air Conditioning Mode button into MAN but finally decided to give it a try. Then I bumped up the TEMP button a bit and - big mistake - I received a DUCT 2 OVERTEMP CAS Message. I can't remember what the temperature on the HX was but I believe it turned color (yellow or red) so I quickly flipped the MODE button back to AUTO and the message disappeared and the temp dropped. Scared the crap out of me because I was not expecting that dramatic of a temp increase that quickly.

    What surprised me is that the temp started increasing in the cockpit and cabin, and the left side HX (Heat Exchanger) temp jumped up to around 210 and stayed there as the cockpit started to warm. I'm not sure if the problem fixed itself or not, so would greatly appreciate any opinions by others.

    A few takeaways from this, and lessons learned:

    1. Never do what I did. That TEMP button is very sensitive - if you do use it to raise the cabin temp, click it up a bit and wait, while monitoring the temperature on the ECS synoptics
    2. If you do get a DUCT 1 OVERTEMP or DUCT 2 OVERTEMP, the QRH says to set mode to MAN and hold down the temp knob for 5 seconds, then wait 1 minute for the message to extinguish. I made a mistake in flipping the MODE back to AUTO, but in retrospect it was probably the right thing to do and got the temp down much quicker than going to the QRH and looking up the procedure. The message extinguished within a couple of seconds.
    3. I have no idea what the maximum temperature of the HX indication is for normal operations. Anyone know how hot this can get before you get an OVERTEMP CAS message?
    4. The system seems to be operating normally now. Any ideas on how this problem "fixed itself", or did it?
    5. DUCT OVERTEMPS are serious, and could require an engine shutdown, and they happen quickly. That bleed air is HOT!
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  2. Username Protected
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    #2  
    I had this happen to me a few years ago. Ended up being a bad flow control valve. Yes, manual control of the temps is pretty hard. I think there was a software update a while ago that raised the temp limits that set off the alarm so it doesn't scare you to death so easily. I'm not sure anyone has had much luck manually controlling temperatures in flight (I'm sure someone will chime in here if they have a way to do it).

    I now keep a warm coat stowed in the cabinetry near the cockpit. Maybe two as your legs will need one too. It can get pretty cold up there even if the cabin is working okay. I won't mess with manual temp control.
  3. Username Protected
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    #3  
    I had same issue. Likely fcsov value. Che
    Ck page for yellow x on flow control value. Mine intermittent
    would show yellow x.
  4. Username Protected
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       #4  
    I didn't ever see a yellow X on the synoptics page (I'm assuming it would be by the FCV circle?).

    It seems to have "fixed" itself, but I'm suspicious so will watch it over the next few flights.

    Thanks for the help!
  5. Username Protected
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    #5  
    Mine was intermittent for months. One thing I did was turn up the heat early below 10k, and this helped as I believe value sticks easier when cold soaked.
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       #6  
    (Username Protected), I'll try that.

    I had the back panel opened and techs were looking at my FSCU (Flap System Control Unit) after I received a Flap Fail CAS message. Whenever I have a problem right after maintenance, I'm always suspect that something may have been "bumped". Anyone know where the FCV is located?
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    #7  
    I've got the same issue happening occasionally few times over the last two years. Tried the same with MAN temp, got same DUCT OVERTEMP result. As the issue was intermittent, after every occasion maintenance checked and said everything is in order, while two weeks ago they found Temp Modulating Valve guilty as charged and replaced it. Now seems to be OK.
    FIM Task applicable is shown in the CRS as 21-61-00-810-807-A
    Hope that helps, good luck!
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    #8  
    (Username Protected), Had exactly same issue with the temperature not going up. After while slowly fixed itself. My take was warm day in Floriday with very high humidity and the aircon (on GPU) was running a while. Believe some ice blocked air intake through the heater.
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    #9  
    All! Yes don’t ever try to heat cabin up manually unless you do it very slowly and wait and see. The temp over duct warning means if the ECS gets much hotter and you don’t do anything about it (like put back in auto or turn it back cooler) it could end up shutting down pressurization while in flight! Happened to me in a PC12. Same concept. Again, be extra careful with manual adjustments to “hot”!
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    #10  
    Not sure if anyone mentioned this or not but the logic of the ECS through the AMS controller allows the temps to comedown automatically in the event of a DUCT OVERTEMP even in MAN mode. Holding the temp switch down is a redun(Username Protected)cy for the system but when you placed the switch back in AUTO, the AMS controller was already way ahead of you. The checklist is really assuming you were already in AUTO and that mode failed to do it’s job by allowing the temps to run high.
  11. Username Protected
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    #11  
    The best part out Phenoms are the “auto” features. Remember, training everyone - when do we move any toggle out of “auto”? “When the checklist tells us to”

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