Pressurization system completely inaccurate

[09tir98]

No matter what you set on the CABIN PRESSURE CONTROL panel the pressurization system will always pressurize the cabin to a cabin altitude of 0ft until reaching the maximum delta P. At that point the cabin will start climbing rapidly (needle maxed out) and maintain maximum delta P instead of slowly climbing to the cabin altitude set on the pressurization controller. 

[IniJamir]

Hello, I will pass this along to the team, thank you.

[IniJamir]

Hi, @09tir98 we tested this on our end and it appears to be working, can you verify that you set the pressure via the ALT SEL Switch

[09tir98]

1 hour ago, IniJamir said:

Hi, @09tir98 we tested this on our end and it appears to be working, can you verify that you set the pressure via the ALT SEL Switch

Yes, I set the ALT SEL correctly to my cruise. I just did a test and this is what I experienced with the pressurization:

Initially, after takeoff the cabin was climbing at roughly 1000 ft/min which is also what it does in your picture. This is incorrect as it should climb with 500 fpm with the rate knob at the white dot. It kept this 1000ft/min climb until passing 2000 ft.

When reaching 2000 ft the cabin instead started descending, with the needle maxed out at -2000 ft/min until the cabin reached an altitude of 0 ft. It then maintained a cabin altitude of 0 ft until the delta P reached the red mark at around 20000 ft.

At 20000 ft, the cabin altitude finally started climbing, this time with a rate of 1250 ft/min. It kept this climb rate until I leveled of at 24000ft.

When I leveled off at 24000 ft the cabin altitude was at 500 ft and a delta P of around 8.6. This does not match the cabin altitude of 5300 ft shown in the CAB window with the ALT SEL set to 24000 ft.

 

What it actuallly should do, with the rate selector set to the white dot is climb the cabin at 500 ft/min until reaching the CAB altitude in the ALT SEL window corresponding to the selected cruise altitude.

 

 

ON GROUND:

 

PASSING 3000 ft:

 

PASSING FL200:

 

LEVEL AT FL240:

Edited Friday at 07:39 PM by 09tir98

[09tir98]

The CAB part of the ALT SEL window also seems incorrect. It is supposed to show the cabin altitude with the cabin pressurized to maximum differential. In the example with the FLT ALT set to 24000 ft the CAB ALT shows 5300 ft. However, at 24000 ft the cabin pressurizes to 500 with the pressure differential at maximum. So with the FLT ALT set to 24000 ft the CAB ALT should only show 500 ft. In the following manual you can see that with the FLT ALT set to 34000 ft the CAB ALT shows 5000 ft which also corresponds to a differential pressure of around 8.6.

 

So this seems to be a two part problem.

1. The cabin altitude doesn't climb with a consistent rate of 500 ft/min and descend with a consistent 300 ft/min.

 

2. The CAB ALTs in the ALT SEL window do not represent the cabin altitude at maximum differential pressure. With the FLT SEL set to 34000 ft the CAB ALT should display roughly 5000 ft, however in the simulator the CAB ALT window displays 5000 ft with the FLT ALT set to below 24000 ft.

 

[IniJamir]

I've passed this additional info to the team, thank you 🙂

[Nitsaw]

Glad it's not just me having cabin pressurization issues!