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JPL19

Pressurization still

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The previous thread was locked, but this is not a case of not reaching TOGA Mode.

 

I am following the correct protocol, including no slewing, etc, (tried with no GSX as well).  100% sure I am entering TOGA on my takeoff roll well before 80kts.  Landing field elevation set (7840 for KASE).

 

Pressurization seems to hold at 1,000 during initial climb, until somewhere around 20,000, then suddenly rises to aircraft altitude and keeps climbing with the aircraft regardless of any settings.  Manual mode refuses to work, making for two ruined flights in a row.

 

CRJ-700 v 1.2.2.0 in P3Dv4.3, Win 10.  Flight plan is KLAX ORCKA3 LAS J146 DVC DCT LOYYD DCT SKIER DCT DBL DCT KASE

 

Joe L.

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Your pressurization was indeed working if it held 1000 feet cabin altitude initially. Differential pressure of 8.0 psi typically happens around 20,000 feet. At that point, cabin altitude should slowly start to rise to hold the differential at around 8 psi. If the cabin suddenly went straight to current altitude while passing 20,000 feet something definitely went wrong.

 

The previous problem was that the pressurization would not work at any point after takeoff if the throttles did not reach TOGA. Doesn’t seem to be the case here...

 

I have not tried the latest update yet. I also have P3D 4.3. I’ll try your flight plan and see what happens.

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I have encountered the same issue with pressurization on three consecutive flights.  Thought I was doing something wrong at first, but I checked landing field elevation and it is set.

 

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2 hours ago, cparrott73 said:

I have encountered the same issue with pressurization on three consecutive flights.  Thought I was doing something wrong at first, but I checked landing field elevation and it is set.

 

 

Wait...upon further inspection, I discovered I neglected to turn on the hydraulic pumps (other than 3A) on my latest flight.  Ugh.  I *hate* it when I do silly things like this!

/feeling sheepish

Could this have caused the sudden loss of pressurization?  I got the same symptom as reported above - pressurization fine until about 20000 feet, with cabin altitude hovering around 1000-2000 feet or so.  Then, complete loss of pressurization, and cabin altitude shoots up to the current altitude the plane is traveling at.  I did make sure to take off using the TOGA detent on the throttle.

Guess this pilot needs some more training in the sim...  ;-)

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In my case hydraulic pumps are on . . .

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Hydraulics is unrelated to pressurization. However bleed air and packs are important. Please check if those were on.

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I can verify this problem. I tried the same flight plan as the OP: KLAX ORCKA3 LAS J146 DVC DCT LOYYD DCT SKIER DCT DBL DCT KASE. The takeoff and landing runways and cruise FL were not specified. I took off from KLAX 25R, and programmed the LOC 15E approach at KASE, with the DBL transition. Cruise FL was 330.

 

CRJ-700 in UAL livery. Version 1.2.20, P3D 4.3 Win 10 Pro

 

Default "Clear" weather theme with no external weather.

 

I did a 45C FLEX takeoff at TOGA power setting, with a reduction to climb thrust at 1,500 feet AGL. After engine start, (and before takeoff), I dialed the KASE landing elevation of 7,840 feet into the pressurization controller.

 

Everything was fine during the initial climb. The cabin altitude was about 3,000 feet with Delta P of about 7.0 psi passing 20,000 feet. The cabin was climbing at about 300 fpm at that point. At 21,000 feet the cabin rate of climb suddenly went to zero, and at 21,400 feet, the cabin instantaneously went to actual aircraft altitude, with Delta P of zero, with all the associated alarms.

 

Something to do with the high elevation of the destination  airport perhaps? I did a flight earlier today from DTW to LGA, (elevation 20 feet), also at FL 330, and had no pressurization problems.

 

Jim Barrett

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Hi

Exactly what happened to me earlier.  I tried another flight today from KIRW to KASE.  All was fine as prescribed here and manuals.  TOGA is set and off we go.  Due to route constraints, initial climb was to A170, then A160, then F250.  all was fine climbing to A170, the pressure differentials normal.  the instant I touched the altitude knob to change to A160, cabin altitude was A170 and we know the rest.  Something is triggering this in effect.  Good luck and thanks in advance.

Jead

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9 minutes ago, Jead said:

Hi

Exactly what happened to me earlier.  I tried another flight today from KIRW to KASE.  All was fine as prescribed here and manuals.  TOGA is set and off we go.  Due to route constraints, initial climb was to A170, then A160, then F250.  all was fine climbing to A170, the pressure differentials normal.  the instant I touched the altitude knob to change to A160, cabin altitude was A170 and we know the rest.  Something is triggering this in effect.  Good luck and thanks in advance.

Jead

 

In my case, I had a continuous climb selected on departure from LAX to FL330

 

Was KIRW a typo? I can’t find an airport with that identifier. It would be unusual to have an enroute climb waypoint with a lower altitude after a higher one (160 following 170). The letter “A” normally indicates “At or Above”, so if you crossed the first A170 waypoint at 17,000 feet, you would just keep climbing to cross the A160 waypoint at 17,000+

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Ooops.  KRIW.  I did a quick plan with pfpx to test the pressure issue.  I didn't realise the plan was abit strange till now.  This was the plan from pfpx

N791SK-IN
-CRJ7/M-SDE1FGHIJ1RWXYZ/LB1
-KRIW1200
-N0469A170 DCT RIW V187 SWEAT/N0471A160 V187 OCS/N0430F378 J206 DBL DCT
-KASE

 

Some strange values there. I will try it again later with better values for altitude.

Jead.

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7 hours ago, JRBarrett said:

I can verify this problem. I tried the same flight plan as the OP: KLAX ORCKA3 LAS J146 DVC DCT LOYYD DCT SKIER DCT DBL DCT KASE. The takeoff and landing runways and cruise FL were not specified. I took off from KLAX 25R, and programmed the LOC 15E approach at KASE, with the DBL transition. Cruise FL was 330.

 

CRJ-700 in UAL livery. Version 1.2.20, P3D 4.3 Win 10 Pro

 

Default "Clear" weather theme with no external weather.

 

I did a 45C FLEX takeoff at TOGA power setting, with a reduction to climb thrust at 1,500 feet AGL. After engine start, (and before takeoff), I dialed the KASE landing elevation of 7,840 feet into the pressurization controller.

 

Everything was fine during the initial climb. The cabin altitude was about 3,000 feet with Delta P of about 7.0 psi passing 20,000 feet. The cabin was climbing at about 300 fpm at that point. At 21,000 feet the cabin rate of climb suddenly went to zero, and at 21,400 feet, the cabin instantaneously went to actual aircraft altitude, with Delta P of zero, with all the associated alarms.

 

Something to do with the high elevation of the destination  airport perhaps? I did a flight earlier today from DTW to LGA, (elevation 20 feet), also at FL 330, and had no pressurization problems.

 

Jim Barrett

 

You might be on to something here.  I encountered this exact same problem while flying CYYZ to KDEN, which is also a high-altitude airport.  (Landing field elev. 5440'.)

Here was my flight path, for reference:

CYYZ GOPUP3 SLLAP DCT BAE DCT ALO DCT OBH WAHUU2 KDEN

Cruise level at FL360 for the entire flight.

 

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8 hours ago, Hans Hartmann said:

Hydraulics is unrelated to pressurization. However bleed air and packs are important. Please check if those were on.

 

Thanks...I figured as much, but just wanted to rule it out.

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Some kind of bug may have been introduced into the pressurization logic since SP1 was initially released. The sudden loss of cabin pressure is definitely linked to the setting of the landing altitude knob to a "high" field elevation like Denver or Aspen. If the landing knob is set to a more "typical" landing elevation - somewhere between sea level and 3000 feet or so - the pressurization appears to work fine.

 

In the initial post in this thread, JPL19 mentioned that on a KLAX-KASE flight, he had preset the 7,840 foot landing field elevation for Aspen (KASE) prior to takeoff. I did the same thing, using his same flight plan, and had the same result - a sudden complete loss of cabin pressure at about FL 210.

 

In r/w operations, crews typically would not set the landing elevation prior to takeoff. It would normally be set once reaching cruise altitude, once the pilots are certain that they will indeed be landing at their intended destination, and will not be diverting to a different airport due to weather or other inflight problems. However, it really does not make a difference, since the actual pressurization controller does not start calculating a descent profile until after the aircraft has established at cruise altitude.

 

In any case, I flew the KLAX-KASE flight again, but this time I left the landing elevation set to its default of zero feet. On this flight, pressurization was fine initially - It stabilized at 5,400 feet cabin altitude, with a differential pressure of 8.3 psi after leveling off at FL 330. After a few minutes in cruise, I started to dial up the landing altitude knob to target the Aspen elevation of 7,840 feet. At some point when the elevation knob was around 5000 feet, the pressurization suddenly failed as before, with an instantaneous cabin altitude of 33,000 feet, and a differential pressure of zero psi.

 

This is something new. During testing just prior to the release of SP1, I flew several flights to and from Denver, with no problems. I know that Hans recently made a change in the pressurization code to eliminate the requirement to achieve TOGA thrust on takeoff, and perhaps that introduced a bug.

 

I'm sure Hans will look into this. In the meantime, the best advice I can offer is to avoid flying to high-elevation airports until this problem is corrected.

 

Jim Barrett 

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There is absolutely no doubt about that at all Hans.  Thanks so much for all.

Jead

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14 hours ago, JRBarrett said:

In r/w operations, crews typically would not set the landing elevation prior to takeoff. It would normally be set once reaching cruise altitude, once the pilots are certain that they will indeed be landing at their intended destination, and will not be diverting to a different airport due to weather or other inflight problems. However, it really does not make a difference, since the actual pressurization controller does not start calculating a descent profile until after the aircraft has established at cruise altitude.

 

This appears to be operator dependent as we set landing elevation during the initial setup of the aircraft prior to even engine start.

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15 minutes ago, Propane said:

 

This appears to be operator dependent as we set landing elevation during the initial setup of the aircraft prior to even engine start.

Yes. The setting won't really have any effect on system operation early on in any case. The pressurization controller internally "remembers" the departure field elevation for several minutes after takeoff, in case the aircraft has to make an unplanned return - one less setting for the crew to worry about.

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I just flew the problematic KLAX to KASE flight, using the same flight plan as before with the new 1.2.2.1 build. (Note: you have to have the option to receive “experimental” builds checked in the updater to receive this particular update.)

 

I set the KASE landing elevation of 7840 feet into the controller before departure from KLAX. Had no problems at all. Previously the pressurization would fail climbing above 20,000 feet. Now the cabin rate of climb and differential pressure scheduling was perfect, and stabilized at 5,400 feet at 8.3 psi at my cruise altitude of FL330.

 

Cabin altitude on descent was pretty good. It remained at about 5,400 for most of the descent (as differential pressure decreased). It rose to about 6800 feet just before touchdown, and went to field elevation when I landed. That would be a bit of a harsh pressure transition on touchdown in the real aircraft as far as passenger comfort is concerned, but “close enough” IMO.

 

I was high on final and had to increase my descent rate quite a bit for the last segment of the approach, so that may have been part of the problem.

 

Tomorrow I will try the return flight to LAX, to see how the pressurization works taking off from a 7,800 foot field elevation.

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4 hours ago, JRBarrett said:

I just flew the problematic KLAX to KASE flight, using the same flight plan as before with the new 1.2.2.1 build. (Note: you have to have the option to receive “experimental” builds checked in the updater to receive this particular update.)

 

...

Thanks for the update, I did not have experimental updates checked, but, do now.  Will be able to give it a go this weekend.

 

Joe

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I did the return flight KASE to KLAX in the United CRJ-700, with version 1.2.2.1 in P3D 4.3.

 

Cruise altitude was 36,000 feet. This time I used RW weather injected by ASP4. I preset the KLAX landing altitude at 100 feet prior to engine start. Pressurization was flawless. At ASE prior to takeoff, cabin altitude was at the field elevation of 7,800 feet. Immediately after takeoff, cabin altitude climbed to 8,000 feet and held there solidly throughout the climb as differential pressure slowly increased.

 

After leveling off at FL360, the cabin altitude slowly descended to 6,400 and stabilized there at a differential of 8.3 psi. The cabin descended correctly on arrival, and differential reached zero just before touchdown.

 

At least in P3D 4.3, it definitely seems that the pressurization bug is fixed when landing or departing from high altitude airports. I believe Aspen is the highest elevation airport that a CRJ operates from in r/w airline service, so if it works there, it should work fine at DEN, ABQ etc.

 

There were some scattered thunderstorms over northern Arizona, and the radar did depict them, but it was hard to tell if their placement on the MFD display was accurate, because they were quite far left of my course, and only showed up at the edge of the display. The aircraft made a 35 degree right turn at a flightplan waypoint, and the displayed cells did move farther left until they were no longer visible on the radar display. As the cells were moving out of view in the turn, it also seemed as if they were moving forward at the same time (as if their displayed distance was increasing as the aircraft heading changed), but that may have been an illusion. I’ll have to do a flight towards an area of known thunderstorms with ASP4 active to do more testing of the radar display in turns.

 

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vor 16 Stunden , JRBarrett sagte:

At least in P3D 4.3, it definitely seems that the pressurization bug is fixed

The pressurization system doesn't use anything from the FSX/P3D system except for the altitude MSL/AGL and vertical speed. So, there's no reason why it would behave any different in FSX.

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42 minutes ago, Hans Hartmann said:

The pressurization system doesn't use anything from the FSX/P3D system except for the altitude MSL/AGL and vertical speed. So, there's no reason why it would behave any different in FSX.

Wasn’t sure if there would be any difference. The problem of the cabin suddenly depressurizing at FL200 when a high landing elevation is selected on the controller is definitely no longer a problem in 1.2.2.1

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Unfortunately, I am still having pressurization issue when flying from high elevation airport to high elevation airport (KDEN - KJAC). I even tried setting the landing alt at 0 for KJAC and the aircraft over pressurizes past max press diff. When I set the landing elevation to foeld elevation at KJAC, the cabin altitude goes to the aircraft's altitude automatically. 

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I am not using the experimental built, but I am having pressurization problems on ALL flights.  I have followed the checklists and procedures, but no matter what I do, I either get a stuck pressurization (set landing alt after departure) or no pressurization (set landing alt before departure).  What for me is the worse issue is that MAN control doesn't work - period.  I have switched to MAN, increased rate to max, set cabin alt to DESC, and the rate stays firmly at 0.  Tried changing landing alt to 0 and landing alt.  Tried even changing it to a high alt and then back down and nothing got it to work.

 

I did verify that all pneumatic systems are correctly set with both packs on, including cycling them.  I also verified that all doors are closed.

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