17 Nov 2025, 11:27 [ UTC - 5; DST ]
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Post subject: Re: Single engine pressurized above FL 250  Posted: 09 Jan 2015, 18:41 |
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Username Protected wrote: I never even considered losing my engine at FL270 may cause depressurization. It also means I'm gonna descend. Nooooooooooo. I'll have to put my O2 mask on and find a place to land.
Of course, how many times has this happened? I dunno.
Hey, tell me about the Phenom 100 with the pro pilot flying that crashed into that house last month and killed 6 people. I'll bet that accident really changes the rules for twin engine airplanes. 421 over the gulf Payne Stewart Lear JFK Jr. Bo Rein 1980 in a 441 Lear 24 - Mexico 1998 Super King Air 200 - 2000 Australia 2005 Helios Airways Flight 522 crash (pilot induced)
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Post subject: Re: Single engine pressurized above FL 250 Posted: 09 Jan 2015, 18:42 |
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Joined: 01/29/08
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Username Protected wrote:
421 over the gulf
Payne Stewart Lear
JFK Jr.
Bo Rein 1980 in a 441
Lear 24 - Mexico 1998
Super King Air 200 - 2000 Australia
2005 Helios Airways Flight 522 crash (pilot induced)
PC12 I mean. But it's strange to see it happen to so many twins right? After all, they're much safer.
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Post subject: Re: Single engine pressurized above FL 250 Posted: 09 Jan 2015, 18:46 |
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Username Protected wrote: I'm arguing your point.
Pressurization issues are not exclusive to singles by any stretch. Gotcha. Damn forums.
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Post subject: Re: Single engine pressurized above FL 250 Posted: 09 Jan 2015, 18:57 |
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Username Protected wrote: Uh, no, you are REQUIRED to have a sufficient amount of flow into the cabin so people can BREATHE.
It is not sufficient to just make the cabin have PRESSURE. That would be like putting people in a tank with no air exchange.
So the way systems are designed is that they provide that required IN flow, and then use OUTFLOW valves to keep the pressure up.
So your electric system would have to have the same flow rate or nearly so.
Why would it? If it's a 6 place plane, count 6 people, what do they breathe at normal lung capacity? Google gives the answer: about 12 breaths per minute, each about 1 litre. That's 12 litres per person per minute, or 72 litres in total per minute. That's 2.54CFM when you convert it. That's the air exchange that needs to take place.
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Post subject: Re: Single engine pressurized above FL 250 Posted: 09 Jan 2015, 19:04 |
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Username Protected wrote: The 421 over the gulf was a suicide. Is my memory incorrect? I thought there were two on board??
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Post subject: Re: Single engine pressurized above FL 250 Posted: 09 Jan 2015, 19:05 |
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Username Protected wrote: The 421 over the gulf was a suicide. Geez. There are less expensive ways to go.
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Post subject: Re: Single engine pressurized above FL 250 Posted: 09 Jan 2015, 19:10 |
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Username Protected wrote: The 421 over the gulf was a suicide. Geez. There are less expensive ways to go.
Not if you want a painless way that isn't conclusively a suicide.
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Post subject: Re: Single engine pressurized above FL 250 Posted: 09 Jan 2015, 19:19 |
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Username Protected wrote: An adult consumes about 300ml/minute of oxygen (say 1.5l fresh air). That's not a huge inflow requirement. Co2 production is a roughly similar volume. So a 6 person plane would need 10, maybe 20L, of fresh air per minute. If you can get ALL of that new air to go RIGHT to the person breathing it, then yes, that is all you need. Otherwise, your inflow is mixing with the exhales and diluting your new oxygen and concentrating your old CO2. Eventually you end up with dangerously high CO2 and low O2 levels. Apollo 13 anyone? The air flow requirement was determined so that there is sufficient air exchange to provide good human comfort. Mike C.
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Post subject: Re: Single engine pressurized above FL 250 Posted: 09 Jan 2015, 19:20 |
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Username Protected wrote: http://www.flyingmag.com/technique/accidents/unresponsive-cessna-421-pilot-crashes-gulf-mexico
Is the one I'm referencing. That's the one. I assume you know the rest of the story.
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Post subject: Re: Single engine pressurized above FL 250 Posted: 09 Jan 2015, 19:33 |
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Username Protected wrote: An adult consumes about 300ml/minute of oxygen (say 1.5l fresh air). That's not a huge inflow requirement. Co2 production is a roughly similar volume. So a 6 person plane would need 10, maybe 20L, of fresh air per minute. If you can get ALL of that new air to go RIGHT to the person breathing it, then yes, that is all you need. Otherwise, your inflow is mixing with the exhales and diluting your new oxygen and concentrating your old CO2. Eventually you end up with dangerously high CO2 and low O2 levels. Apollo 13 anyone? The air flow requirement was determined so that there is sufficient air exchange to provide good human comfort. Mike C.
Must be missing something form my gas theory classes, but why would CO2 concentrate and O2 dilute over time if 1.5L exchange rate was maintained. Cabins are not large enough to allow gasses to concentrate in one area. Not being sarcastic, just trying to understand.
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