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Pressurization


rmeier

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OK, so I haven't flown the CRJ 900 in about 4 months. This morning, I downloaded the V1.2 update from Simmarket. I have now un-installed/re-installed the software 3 times and still cannot get the pressurization to function. Everything else now (after the second install) appears to work with the exception of the pressurization. The last test flight I ran, I loaded a default P3D aircraft (running), loaded the CRJ (running, on the default runway), loaded the FMC info for my test flight and still no pressurization.

I realize I haven't flown this bird in a while, but, I never had this issue through all the previous version...can anyone offer some suggestions?

On my last flight, I did test the manual over-ride...I was able to slowly increase diff pressure manually, but, cabin altitude never changed. The behavior acts like I'm forgetting to turn on a pressurization valve...I don't remember there being one for this A/C.

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I've tried several things to make this issue go away...no luck so far. I uninstalled again and noticed that the Digital Aviation folder was still remaining in the documents folder...deleted that folder (had some older files from last August!)...no success. I am running a full install of P3D V4.3 and the latest version of FSUIPC (5.132). I've re-installed the MS Visual C++ 2017 files...no success.

I've tried setting up different panel states through Dave...C&D, Turnaround and Ready to Taxi as well as leaving the A/C "as is" following a load after the default (running) aircraft. All show the same symptoms. I don't recall from the last version (it's been a while since I've flown this A/C), but, it appears the FMC is not picking up (transferring) the landing altitude at either the departure, nor arrival airport. I'm using an updated NavDataPro database (1806). I've tried different departure/arrival routes (elevation changes) to see if there may be a problem in the database...no conclusions found.

Right now, the only "success" I'm having at flying the A/C right now without a pressurization fault is to switch the pressurization to manual as I pass through an altitude between 3000 - 5000' (depending on intended altitude) and letting the delta P adjust for actual altitude. So far, I haven't come across a "fix" for this issue...based on the lack of response to my initial query, it would seem the issue rests with my configuration.

To the best of my knowledge, all of my drivers are up-to-date (running Driver Booster 5.5). P3D V4.3 has been running very well for me since the upgrade from 4.2...no CTD's and very smooth frame rates. I haven't had any issues with any other 3rd party A/C so far either (PMDG, Majestic, FSL, RealAir TDuke, etc).

Hopefully someone here can provide some additional thoughts on what I can try.

Thanks, Rob

 

The two attached photos show the ECS screen following my last test flight out of CYUL...the second photo just shows that at 3500' I switched the pressurization to manual which "freezes" the cabin altitude while letting the delta P catch actual altitude...a temporary work-around.

 

 

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Same here, i couldnt get automatic pressurization. If i leave FL100 Cabin Altitude warning is displayed and Cabin Alt is rising withe the planes alt.

Could one of the experts explain how to setup the pressurization for a flight.

Chris

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During the testing phase, one tester having this problem, which Hans found was related to using the pause or slew function at some point prior to or after takeoff. I know he implemented a fix in the code for that, but the bug may still exist, or perhaps something else is causing it. The majority of testers had no pressurization problems. 

 

It it works well on my P3D 4.3 installation. 

 

I always begin my flights lights from the cold and dark panel state FWIW.

 

Hans also found out prior to the release of the new version that the landing altitude is not sent to the pressurization controller from the FMS in the actual aircraft so that feature was removed. Landing altitude needs to be manually set on the pressurization controller - but even if that is not done, it shouldn’t prevent the aircraft from pressurizing properly in a climb.

 

I believe Hans was planning to take a couple of weeks vacation now that the SP has been released, so he may not be able to address this right away.

 

Jim Barrett

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vor 1 minute, JRBarrett sagte:

I believe Hans was planning to take a couple of weeks vacation now

Nope. I'm here. It's just going to be a few CRJ-free weeks before I move on with developing new features. Bug fixing and forum support will continue.

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8 minutes ago, ChrisK said:

Same here, i couldnt get automatic pressurization. If i leave FL100 Cabin Altitude warning is displayed and Cabin Alt is rising withe the planes alt.

Could one of the experts explain how to setup the pressurization for a flight.

Chris

There is really no setup required other than making sure that both packs are running prior to takeoff, and all doors are closed. The crew needs to set the landing airport elevation at some point prior to descent, but other than that, the system is completely automatic.

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Thanks for the feedback...I did not use pause or slew on any of my test flights. I do not recall any pressurization problems on any prior versions of the CRJ. Really pleased with the changes in LNAV and the ILS approach with localizer and glideslope worked perfectly on all my test flights. With the exception of this one issue, I really like the improvements to the CRJ!

Thanks, Rob

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Jim,

I appreciate your comments...they gave me an idea that worked! I started to think that the logic had to be pretty simple...packs on, doors closed (and a likely throttle position). I re-calibrated my (CH) throttle quadrant (and also had to change the default in the AS CRJ Manager Throttle Axis Value Range profile - FSUIPC w/o reverser) and my next two test flights worked as expected! For those two flights, I took off at max throttle.

I reloaded P3D for the third test flight, loaded the CRJ directly from the menu and took off running from the runway, engines running (default load). The only difference on the third flight test is I set the throttles to the TOGA detent...pressurization still worked as expected. I wasn't seeing the "MAX" nor "TOGA" on the PFD before making the throttle calibration. I only have two other aircraft that require FSUIPC calibration of my CH Throttle Quadrant...the FSL Airbus and the XP Lear. At least the pressurization on the CRJ is working now! Jim, thanks for the "thought provoking" idea!

After re calibrating the throttles, I calculated that the #1 throttle was only achieving about 86% of max range and #2 was about 88%.

 

Now one last issue to resolve...the "frog" in the cockpit (continuous loop of the "Knob Turn" sound effect)...luckily, not noticeable with the fan running...only a nuisance in C&D. 

 

Thanks, Rob

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2 hours ago, rmeier said:

Thanks for the feedback...I did not use pause or slew on any of my test flights. I do not recall any pressurization problems on any prior versions of the CRJ. Really pleased with the changes in LNAV and the ILS approach with localizer and glideslope worked perfectly on all my test flights. With the exception of this one issue, I really like the improvements to the CRJ!

Thanks, Rob

This may be a long shot, but check your doors synoptic page before takeoff to make sure that none of the cargo or service doors are open. The aircraft has a prominent red CAS warning displayed when the main entrance door is open, with engines running, but the the warnings for other doors are less prominent even in the real aircraft.

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3 minutes ago, rmeier said:

Jim,

I appreciate your comments...they gave me an idea that worked! I started to think that the logic had to be pretty simple...packs on, doors closed (and a likely throttle position). I re-calibrated my (CH) throttle quadrant (and also had to change the default in the AS CRJ Manager Throttle Axis Value Range profile - FSUIPC w/o reverser) and my next two test flights worked as expected! For those two flights, I took off at max throttle.

I reloaded P3D for the third test flight, loaded the CRJ directly from the menu and took off running from the runway, engines running (default load). The only difference on the third flight test is I set the throttles to the TOGA detent...pressurization still worked as expected. I wasn't seeing the "MAX" nor "TOGA" on the PFD before making the throttle calibration. I only have two other aircraft that require FSUIPC calibration of my CH Throttle Quadrant...the FSL Airbus and the XP Lear. At least the pressurization on the CRJ is working now! Jim, thanks for the "thought provoking" idea!

After re calibrating the throttles, I calculated that the #1 throttle was only achieving about 86% of max range and #2 was about 88%.

 

Now one last issue to resolve...the "frog" in the cockpit (continuous loop of the "Knob Turn" sound effect)...luckily, not noticeable with the fan running...only a nuisance in C&D. 

 

Thanks, Rob

Good to know! I use the CH throttle quadrant and pedals and had similar issues with several add-on aircraft originally. Mainly inconsistent throttle operation and overly-sensitive brakes. I downloaded the CH Manager program to handle calibration of my quadrant and rudder pedals and both have been working well ever since.

 

Hans worked very hard to optimize the pressurization system for this release, so that it would work accurately even when taking off or landing at high-altitude airports like Denver.

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Another hint for "Hans the Bug Hunter";)

I'm starting P3D selecting the CRJ and my fav Airport, so the CRJ will be loaded with engines running. Then i use Dave to switch to turnaround Mode, maybe this will influence the press. Logic.

And also i'm using GSX for pushback, i assume this will be done with slew mode or how do they move the ac ?

Chris

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vor 8 Minuten, ChrisK sagte:

And also i'm using GSX for pushback, i assume this will be done with slew mode or how do they move the ac ?

That actually could be the reason. I rarely actively use GSX because most of what I do is test flying. I'll try this as soon as I finished the test flight I'm currently on.

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I use GSX on all my CRJ flights and the only had pressurization issues on a few of the dozen flights I have done. Only thing I stopped using is FSRealTime which will pause the sim as time is updated. No pause, no pressure problems. 

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I tried. Loaded my default situation (Bonanza on RW 07C in EDDF), loaded the CRJ, changed position to parking V108 and finally switched to Turnaround state.

Following that, I had GSX push back the aircraft and started the engines. Packs were on already, so that can't be the problem. I flipped all other switches necessary to get rid of the yellow EICAS messages (that's true professionalism! Checklists are for the weak and timid ;)) and took off. Pressurization worked just fine.

One thing that could be the case. From ground to climb, the pressurization system goes through certain steps. These are:

  1. Ground mode (Outflow valve fully open)
  2. Pre-Press mode (Outflow valve fully closed) activates when active mode is Ground mode, both engines are running and both throttle levers are in TOGA or MAX position. Pre-Press mode pre-pressurizes the cabin at a fixed rate of 300ft/min
  3. Takeoff Abort mode (Outflow valve fully opened) activates when Pre-Press mode is active and both throttles are pulled back to idle
  4. Climb mode (Outflow valve closed) activates when Pre-Press mode is active and aircraft is airborne
    • during initial climb up to 2000ft AGL, the fixed cabin climb rate of 300 ft/min is maintained
    • above 2000ft AGL, the cabin rate is dynamically calculated to approach the appropriate cabin altitude for the current aircraft altitude

There are more modes but these are the ones that are relevant for this problem.

Regarding Pause and Slew:

  • if Pause is active (or the simulator is halted in another way; for example due to an open window), the pressurization system is paused too
  • The same is true for slew mode except if you make altitude changes. Setting the aircraft to a new height causes the pressurization system to be reinitialized for the proper cabin altitude.

From this list of items, do you see anything that you have done differently or haven't done at all? Throttles not in TOGA or MAX would be keep the aircraft in ground mode for example.

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This is a very useful hint by Hans:

" Throttles not in TOGA or MAX would be keep the aircraft in ground mode for example " should it stay at TOGA until Cruise (what might be not correct) and what happens when i use the CLB detent (what i do most of the time) after takeoff ?

Chris

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Hi Chris,

 

the condition mentioned by Hans only has to be fulfilled once, so if you set the thrust levers into he ground and then reduce to CLB in Climb everything is fine. Of course your do not need to climb up to cruise level in TOGA mode.

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Chris,

What I found on my set-up, prior to re-calibrating my CH Throttle Quadrant, I was seeing full range movement of the throttles (from idle through to max). What I wasn't seeing was the "physical" stops at each of the upper Climb, TOGA and MAX detents. After I recalibrated through FSUIPC (and changed the throttle value in the CRJ Manager), the visual throttles would make a noticable "stop" movement at each of the upper detents. It wasn't until my re-cal that I also observed the "TOGA" and "MAX" display briefly on the PFD. I've made 5 flights since and everything has worked well.

Hope this provides some additional clarification.

Regards, Rob

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I too seem to be having a pressurization issue after installing v1.2, Never had the problem in previous versions.

 

After 14000ft, cabin Alt warning display, followed by Pass Oxy On Caution, and Cabin Alt Warning. 

My procedures haven't changed in all the versions. Not sure what's causing it. 

 

Don't use Toga on takeoff (or max) throttle. 

 

What other info can I give to help track down the issue, please let me know. 

 

Thanks - hope to have a resolution.

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3 hours ago, bhorv67 said:

Don't use Toga on takeoff (or max) throttle

That may be the cause of the problem. If you do not advance the throttles to the TOGA gate on takeoff, it appears that the pressurization system will not initialize properly

 

Though that is not 100 percent accurate as to how the real aircraft works, Hans did a lot of fine-tuning of the pressurization system to make the cabin pressure vs. altitude as accurate as possible - especially with departures or landings at high elevation airports. The requirement to achieve TOGA on takeoff may be a consequence of the refinements to the overall pressurization system in the sim.

 

Pressurization issues aside, you should be using TOGA on every single takeoff. The aircraft’s takeoff performance predictions and flight director behavior in the initial climb are all predicated on the amount of engine thrust produced when the power levers are in the TOGA detent. With a FADEC-controlled engine, taking off at TOGA power is standard procedure. At less than TOGA thrust, the aircraft will use considerably more runway to achieve the calculated rotation/liftoff speed than what the FMS calculated. On a short runway, this could be a big problem.

 

 

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2 hours ago, JRBarrett said:

That may be the cause of the problem. If you do not advance the throttles to the TOGA gate on takeoff, it appears that the pressurization system will not initialize properly

 

Though that is not 100 percent accurate as to how the real aircraft works, Hans did a lot of fine-tuning of the pressurization system to make the cabin pressure vs. altitude as accurate as possible - especially with departures or landings at high elevation airports. The requirement to achieve TOGA on takeoff may be a consequence of the refinements to the overall pressurization system in the sim.

 

Pressurization issues aside, you should be using TOGA on every single takeoff. The aircraft’s takeoff performance predictions and flight director behavior in the initial climb are all predicated on the amount of engine thrust produced when the power levers are in the TOGA detent. With a FADEC-controlled engine, taking off at TOGA power is standard procedure. At less than TOGA thrust, the aircraft will use considerably more runway to achieve the calculated rotation/liftoff speed than what the FMS calculated. On a short runway, this could be a big problem.

 

 

That's what it was. Thanks.

Not sure how I missed that. It's been a while since I've flown the CRJ regularly. Forgetting some procedural items. 

Glad it's just me being dumb. 

 

Great job again on the CRJ. 

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Good to know. To avoid issues like that for the future, I will make another little change to the auto pressurization system. Right now, TOGA is required to switch from ground to pre-press mode. And right now, no direct way from ground to climb mode is implemented. Only ground -> pre-press -> climb. So what I'm going to do is to add a way to switch directly from ground to climb. That will sort the problem once and for all.

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