It doesn't seem like there is much to it.. don't you just set your flying alt..? what else is there to do?

 

I'm getting the warning light coming on saying cabin/alt..

 

thanks

BrianS

I m no expert but here is an answer.

 

You set the desired altitude and you can follow the cabin altitude and pressure difference in the pressurization gauge. When Cabin Alt warning light turns on means you reached the limits of pressurization confort: i guess around 10.000 feet cabin altitude. And further you could reach the red area of cabin and outside cabin differential pressure.

 

I hope all I say is right. At least that is the way I understand it.

 

Have a good evening.

 

Souheil

Check out Chapter 12, Pressurization, in the FlightSafety King Air C90A/B Pilot Training Manual.

 

http://www.warmkesse...ir/C90ABPV2.pdf

As a quick guide, set to 500' above planned cruising altitude and rate knob to 500 fpm (which is default). That will cover most operations. When changing a set altitude, until you are really familiar with the specific aircraft idiosyncrasies, your passengers will appreciate you turning the rate knob to minimum before moving the altitude selection, then slowly raising the fpm to that 500 rate. I've been in a Pilatus where the pilot forgot to set the environment switch (how that pressurization system is turned on) until after the annunciator light and alarm came on passing through 12,500 feet in the climb. The resultant sudden cabin pressure change was a bit painful!

Here's some good RW information that I've been following in my flights. This information is from Tom Clements (a RW King Air pilot with 15,000 hours in type) and detailed in his book "The King Air Book" - I just finished reading the chapter on pressurization so it's apropos to the question. :)

 

Clements recommends two operational changes to the pressurization process for the King Air:

1. Climb and Cruise - Set your pressurization controller to your cruise altitude (not +500 or +1000 feet). Mr. Clements argues that this procedure of setting the pressurization controller to a higher altitude is an anachronistic practice left over from the early days - think mid-1960's - when Beech was developing procedures for the King Air. In those days, passengers (and pilots) often smoked while on board the aircraft. The theory is that the tar and residue from the cigarettes caused the pressurization system to not operate as smoothly as it could because the residue from the cigarettes partially obstructed the relief valve's opening. At that time, the extra 500-1000 feet was needed to prevent reaching the maximum deferential pressure (ΔP) and to keep the cabin vertical velocity from fluctuating at ΔP. Nowadays, (where smoking while onboard is prohibited), it's not necessary to allow for this cushion and by setting the pressurization controller for your cruise altitude, you'll give your passengers the benefit of a slightly lower cabin.
   
2. Descent: - Reset your cabin altitude while in still in cruise. This will prevent you from forgetting to reset it and causing a lot of ear popping as zfehr mentions above. If you need to climb after you've reset your pressurization controller, simply set the new cruise altitude and the pressurization controller will still be able to keep up (since a C90 at FL220 isn't going to climb to FL260, for example, very quickly). But what do you set it to? 500' above your field elevation or something else? The "right" answer, according to Clements, is to use a bit of work to determine what altitude to set the cabin to based on pressure altitude and not use the "field elevation + 500' " approach. I wouldn't be able to do justice to a description of his approach so here is a great link over to the BeechTalk forums where Clements describes this process (link)
   

 

Enlightening stuff. Now, does any of this have any real implications in the Sim? No, of course not, but I thought it was interesting to read about the best practices approach... :)

Here's some good RW information that I've been following in my flights. This information is from Tom Clements (a RW King Air pilot with 15,000 hours in type) and detailed in his book "The King Air Book" - I just finished reading the chapter on pressurization so it's apropos to the question. :)

 

Clements recommends two operational changes to the pressurization process for the King Air:

[*]Climb and Cruise - Set your pressurization controller to your cruise altitude (not +500 or +1000 feet). Mr. Clements argues that this procedure of setting the pressurization controller to a higher altitude is an anachronistic practice left over from the early days - think mid-1960's - when Beech was developing procedures for the King Air. In those days, passengers (and pilots) often smoked while on board the aircraft. The theory is that the tar and residue from the cigarettes caused the pressurization system to not operate as smoothly as it could because the residue from the cigarettes partially obstructed the relief valve's opening. At that time, the extra 500-1000 feet was needed to prevent reaching the maximum deferential pressure (ΔP) and to keep the cabin vertical velocity from fluctuating at ΔP. Nowadays, (where smoking while onboard is prohibited), it's not necessary to allow for this cushion and by setting the pressurization controller for your cruise altitude, you'll give your passengers the benefit of a slightly lower cabin.

 

I've got Tom's book and video. The video describes the 500 feet higher than cruise altitude setting so the book was a later re-edit! If you don't have Tom's video for the C90 it is so very well done. I've probably watched it 20 times.

I find that chewing gum and yawning is the simplest way to deal with cabin pressurization.....as well as the ONLY way I know about dealing with it :LMAO:

James... you do realize that you just triggered everyone reading this into yawning... DAM.. the very WORD even triggers it!.