PACK Failure at FL350 with no Cautions/Warnings (-200)

C150J

Well-Known Member
Hi guys,

I posted this in the Airline Pilots forums thinking that it would get the most exposure from our current and former CRJ-200 drivers. We had a PACK failure the other day at 350 with no annunciations. The only reason I saw it happen was the fact that the FA called up and said it was pretty hot (full boat), so I switched to the ECS synoptic. I then noticed that the PACK was at 3psi (not regulating at 30psi), and soon after went to 0psi. The green outline of the pack then went to white. No warnings, cautions, or status messages indicated any sort of failure. The cabin altitude began to slowly rise, so our descent to FL250 was expeditious. We then reset the PACK.

Excuse my ignorance of systems logic, but to my knowledge, the only cautions dealing with PACKs are overtemp/overpress. I don't even recall one for freezing a PACK, which I've also seen before. Would the next annunciation have been the CABIN ALT caution at 8,500 cabin altitude? Am I missing something here?

Again, I apologize if I'm having a brain fart... just kind of surprised we didn't even get a R PACK OFF message.

J.
 

BobDDuck

Island Bus Driver
I've actually had this before and our MX guys had to talk to Bombardier about it. Howard may be able to get a more technical answer, but if I recall, as you said, the only system massages associated with the pack itself is the overtemp/overpressure which both lead to a Pack Fault light and the Pack Off message which is advisory only.

The amount of airflow doesn't contribute to any sort of messages or warnings so if a pack freezes up and stops putting out air, unless it over pressures because of it, you'll never know until you start getting cabin warning messages at 8500.

Crazy Canadians.
 

Baronman

Well-Known Member
Strange....

While not a CRJ I've noticed odd Pack scenarios like that in the ERJ, most notably on the ground when I can hear the packs running. Then usually I look over to the APU EGT and see that there's either no load (about 350C) or a reduced (450C) load indicative of one pack operating. No cautions...no warnings. If we proceed to TO like that it'll be with one pack running, but I think usually the condition corrects itself after TO when we switch to engine bleeds from the APU bleed.
 

airlinetoATC

New Member
You said you switched to the ecs page and saw it drop from 3 to 0 then the box went white.

If the FA hadn't noticed and you hadn't switched to the ecs the next message you would have gotten would have been a white status message on EICAS 2 at the same time the box on the ecs page went white. That would have been your only indication.


At our company on the cruise check we are supposed to clear the CAS. That way if status messages are up there it should at least grab our attention.

Im sure you guys do something similar and im sure once that message popped up there you guys would've noticed it.
 

kellwolf

Piece of Trash
You said you switched to the ecs page and saw it drop from 3 to 0 then the box went white.

If the FA hadn't noticed and you hadn't switched to the ecs the next message you would have gotten would have been a white status message on EICAS 2 at the same time the box on the ecs page went white. That would have been your only indication.
Probably would have been a "L/R Pack OFF" status message. I've seen them kick off randomly, but luckily all of my occurrences have been below FL250. I DID have an issue when my FO was transferring the bleeds the other day where the SOV from the engine wouldn't open until I turned the pack off.
 

BobDDuck

Island Bus Driver
You said you switched to the ecs page and saw it drop from 3 to 0 then the box went white.

If the FA hadn't noticed and you hadn't switched to the ecs the next message you would have gotten would have been a white status message on EICAS 2 at the same time the box on the ecs page went white. That would have been your only indication.
What message would appear on ED2 when the Pack Flow PSI went to 0? I just doubled checked the system manual and the only white status message associated with the Pack is L (R) PACK OFF, which was not what had happened in this case. The pack was still working just fine, there was just no airflow coming out of it.
 

airlinetoATC

New Member
True I was assuming that the pack tripped I guess he didnt say that. The pack will sometimes read 0 psi in a power idle descent as well without that message.
 

zmiller4

Well-Known Member
What message would appear on ED2 when the Pack Flow PSI went to 0? I just doubled checked the system manual and the only white status message associated with the Pack is L (R) PACK OFF, which was not what had happened in this case. The pack was still working just fine, there was just no airflow coming out of it.
I think the PACK OFF status message is related to switch position only--not even PRSOV position. At Mesa where they don't turn the pack switchlights off, the PACK OFF message doesn't appear when they push the start switch and the pack SOV's close.

The packs have some weird quicks on the 200. I've gotten a "L 10th ARMED OPEN" status message on an unpressurized takeoff. We had to substantially pull power back on the left side to get the 10th to open. Our procedures for unpressurized takeoffs don't call for reducing power at all.

I agree with the OP--seems like everything happened as it was supposed to. It's a good thing you all caught it before the cabin alt caution.
 

NC_BE300

Well-Known Member
I've had a similar situation like this- last year ON THANKSGIVING!

Very similar circumstance to posters situation, however mine:
Singe Pack Operation aircraft to begin with (1 PACK was differred)
Captains Leg to fly, just after i completed the 10,000ft checklist i cleared the CAS to [MSGS]
Shortly after that, and still during our rapid climb (we had only 8 people onboard), i notice out the corner of my eye that the CAS messages list opened up again. I reviewed the messages, and found a new message ...PACK OFF.
No Caution/Warning messages because there was no OVERTEMP/OVERPRESSURE, and since we were still under 15000 feet, and the cabin altitude didn't reach higher levels. (Just like BobDuck mentioned)
And since we were a single pack operation, we were now not receiving pressurized air.
Stopped the climb immediately, descended, broke out the QRH. Pack didnt reset. Led to Unpressurized flight procedure and a return to the airport for landing since we were close to base.

FUN FUN holiday that was. I'm hoping for a much more calm version this time around when i'm working on thanksgiving.
 

H46Bubba

Well-Known Member
Sounds like the ACM froze up at altitude. It won't give you a message when it does that other than the cabin pressure. The design is a P.O.S. along with every other componant on the CRJ. If it ever happens to anyone else, ask the FA to check the pressure from several of the passengers' air nozzles. I had it happen as a pax on an ASA flight and I got into it with the FA. The cabin got hot as hell and there was no air coming from the overhead or along the floor. Once I told her I was mx at Comair, she informed the crew about what I had said. They were able to expeditiosly get down to a lower altitude and reset the PACK.
 

EDUC8-or

Well-Known Member
It's possible to get a PACK FAIL message, but I've never seen one in flight when the pack just stops working.
 

BobDDuck

Island Bus Driver
Interesting and related, I flew a plane with the right pack MELed all day today. Not a big deal, but we were limited to FL250 and had to do a fancy bleed transfer after take off every time (close the APU LCV and then open the 10th stage left bleed as opposed to the other way around). Anyhow, it was working just fine until on landing when we closed the left thrust reverser, the pack would over pressureize and fault. EVERY single time.
 

zmiller4

Well-Known Member
Interesting and related, I flew a plane with the right pack MELed all day today. Not a big deal, but we were limited to FL250 and had to do a fancy bleed transfer after take off every time (close the APU LCV and then open the 10th stage left bleed as opposed to the other way around). Anyhow, it was working just fine until on landing when we closed the left thrust reverser, the pack would over pressureize and fault. EVERY single time.
That's the only place I've had pack hi press cautions as well--single pack on the rollout. Kinda weird.
 
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