woweezowee

Cabin Pressurization

41 posts in this topic

This is how it works, right? I'm too stupid to set it correctly in the Jetstream, always get the "Cabin" warning when flying 9000+ feet. Can anybody help me out with a screenshot for e.g. flying at 15.000?

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I don't have a screen shot, but what I do after getting the engines running and the generators engaged is:

 

  • Put switch on Dump and allow it to stabilize (climb/descent needle goes back to zero)
  • Put switch back on Pressurization
  • Set Pressure Altitude to 6000 or so
  • Turn air flow knobs up to 3 or 4
  • Turn temperature knobs up to about 8 o' clock 
  • Put the two temperature switches (ganged) on Manual
  • Turn the fan on

The only time I've had a pressure warning is when I've forgotten to put the switch back on Pressurization.

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ok thanks. But I can't change "the thousands", so that I could tune something like 17.000ft… right? That is what I was wondering :o

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thanks. After those answers, I don't know what I did wrong. It "should" have worked like I initially thought, but then I got confused because of the warning and searched for a knob to set altitude 1000 above cruise, … So forget the confusion and just will try again. 

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I don't have a screen shot, but what I do after getting the engines running and the generators engaged is:

 

  • Put switch on Dump and allow it to stabilize (climb/descent needle goes back to zero)
  • Put switch back on Pressurization
  • Set Pressure Altitude to 6000 or so
  • Turn air flow knobs up to 3 or 4
  • Turn temperature knobs up to about 8 o' clock 
  • Put the two temperature switches (ganged) on Manual
  • Turn the fan on

The only time I've had a pressure warning is when I've forgotten to put the switch back on Pressurization.

it does not work. I'm pretty clueless as to why :(

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just a question: do you know what is the use for the RATE knob (see page 45 of the manuel/guide) ?

 

i think the reason why your press. give you some headache is because you forget to set how fast the press. have to change.

 

 

 

 

but i can be wrong. :)

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I turn it up to the 12 o'clock position but have no idea to which rate of climb this corresponds to.

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I turn it up to the 12 o'clock position but have no idea to which rate of climb this corresponds to.

 

in page 44, you can see how fast you press. changes while you turn the RATE knob. (CABIN RATE OF CHANGE IND.)

 

usually, i turn the knob on the right (following the movement of the clock) and i set to 1000 FPM for the rate of change while climbing (and not on the ground cause most of the time, nothing happens on the ground). once it is set, i dont change the rate anymore (maybe it is not the good way, but i see no problem until now).

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in page 44, you can see how fast you press. changes while you turn the RATE knob. (CABIN RATE OF CHANGE IND.)

 

usually, i turn the knob on the right (following the movement of the clock) and i set to 1000 FPM for the rate of change while climbing (and not on the ground cause most of the time, nothing happens on the ground). once it is set, i dont change the rate anymore (maybe it is not the good way, but i see no problem until now).

 

Aim for 300-500fpm for passenger comfort, 1000fpm can be quite uncomfortable for the people in the back ;).

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i don't get it. does the needle show what I have set or does it show the aircrafts climb rate?

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ok, because the damned thing pointed upwards and I again have no pressurization. and it gives no indication prior to flight… only when really changing altitude

Edited by woweezowee
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ok, because the damned thing pointed upwards and I again have no pressurization. and it gives no indication prior to flight… only when really changing altitude

 

this is why you have to set it while climbing.

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The knob is totally defunct in my Jetstream. 

 

http://youtu.be/5cTdHdUlx3I

 

one thing that i remarked is you are setting an CABIN ALT (4000 ft) that is not matching the altitude you want to reach (+9000 ft).

 

this is how i do when setting CABIN ALT. once again, i'am not a pilot irl so i maybe do it wrong but still, i have no problem of press.:

- on ground, i 'dump' the press. so that it matches the one of airport.

- on ground, i set altitude following two rules: altitude between 0 and 10 000 ft, i set to the exact altitude (in your vid, i shall set to 9000ft if my finale altitude is 9000ft/qnh); altitude more than 10 000 ft, i set to max (=10 000 ft). i avoid to flight over 18 000 ft/qnh standard because of the permitted differencial (?), so i choose my flight level between FL150 and FL180, depending on the clouds and the direction (even or odd). for instance, my finale altitude is 16 000 ft, i set CABIN ALT to 10 000 ft.

- after i 'press' (MANUAL CONTROL), once i am climbing, at about 3 000 ft/qnh, i set the RATE while looking at the CABIN RATE OF CHANGE IND. to 300fpm (thx to Intrance). at the finale altitude, i check again CABIN ALT / DIFF PRESS INDICATOR (page 34) and make sure the Inner scale is fine (<5.5psi).

- when descending, i set the CABIN ALT to the altitude of the airport (destination) and see (i dont touch nothing this time !) if the CLIMB is changing (CABIN RATE OF CHANGE IND.)

- once i am on ground at destination, i 'dump' the press. to match the one of airport.

 

as long as you set the RATE while climbing, you dont need to worry about it. just only set the CABIN ALT depending if you are climbing or descending.

 

now, its better if javier or someone else with more experiences will advice you.

Edited by loopylook
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I wanted to climb more, to 15.000ft this time. Still confused.

 

If you watch Keiths video linked to some posts ago: He doesn't even touch the rate knob, climbs to 25.000ft and has the pressure set to 4000. cruster suggested "Set Pressure Altitude to 6000 or so". And yes, I already tried the setting to 10.000, too.

 

So everybody does it different, but it only won't work for me? That's so strange :D I never had such an issue, not in airliners, not in any crazy russian plane, … I'm really out of clues. And please take another look at the PDF that I linked to in my first post. It's yet another explanation. uhhh :(

Edited by woweezowee
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i avoid to flight over 18 000 ft/qnh standard because of the permitted differencial (?), so i choose my flight level between FL150 and FL180, depending on the clouds and the direction (even or odd). for instance, my finale altitude is 16 000 ft, i set CABIN ALT to 10 000 ft.

i know this bird can go higher, but i prefer to fly under the FL180 because the routes are more suitables to that kind of plane (low level --> fly VOR to VOR / high level --> more suitable for planes with FMS)

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I wanted to climb more, to 15.000ft this time. Still confused.

 

If you watch Keiths video linked to some posts ago: He doesn't even touch the rate knob, climbs to 25.000ft and has the pressure set to 4000. cruster suggested "Set Pressure Altitude to 6000 or so". And yes, I already tried the setting to 10.000, too.

 

So everybody does it different, but it only won't work for me? That's so strange :D I never had such an issue, not in airliners, not in any crazy russian plane, … I'm really out of clues. And please take another look at the PDF that I linked to in my first post. It's yet another explanation. uhhh :(

 

well, in this case, i cannot help you. good luck though !

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I hope that Javier, Cameron or real life pilot  will reply here and explain in more details what gauges show exactly and how to use them. :)   Cheers, AJ 

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Well, I now have watched Keiths video at least three times as well as JimboG's aircraft acceptance video, and still don't get where the error could be on my side. I also can't hink of any plugin that I have running in my 64-bit X-Plane that would interfere with pressurerization.

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I hope that Javier, Cameron or real life pilot  will reply here and explain in more details what gauges show exactly and how to use them. :)   Cheers, AJ 

 

The way the add-on is set up doesn't correspond to how to use it in the real aircraft (not trying to bring the addon down, just stating a fact).

 

The dial that indicates the cabin altitude has a subdial at the bottom that indicates the maximum altitude. For climbing, you will normally set it to 1000ft above your filed level. So if we're flying at FL150, we set the subdial to FL160. This keeps a nice margin for the maximum differential pressure. The airplane can keep sea level pressure up to about 13.000ft or FL130, so any flight below that you can keep the pressure set to field elevation or 1000ft above (see next part).

 

For descent, it's common procedure to set the cabin altitude to 1000ft above airport elevation, and correct for temperature and QNH. What this basically ensures is that when you're at 1000ft in the approach and stabilized, the cabin should start descending as well and you can slowly close the flow selectors for a nice transition between pressurized and outside pressure.

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yes, and there it starts to get confusing how to do the correct procedure in the Jetstream. :D

 

However, it can't be that "sensible" in the plugin when everybody uses slighty different settings and it still works for them. How do you do it in the Jetstream?

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