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March 17th, 2004, 07:44
| #1 |
| Junior Member  Join Date: Dec 2003 Location: North East; KFRG
Posts: 66
|  Overpressurization?? What happens if the cabin becomes overpressurized? |
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March 17th, 2004, 08:17
| #2 |
| Old Skool  Join Date: Dec 2002 Location: Utopia
Posts: 12,503
| Re: Overpressurization?? The cabin will burst, and all is lost!!!!! That shouldn't happen, though, because there is at least one pressure relief valce that should open if the cabin pressure exceeds limits. |
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March 17th, 2004, 16:15
| #3 |
| Newbie  Join Date: Mar 2004 Location: Chicago, IL, USA (JOT089/5)
Posts: 16
| Re: Overpressurization?? The 757 has positive relief valves that should open if for some reason the outflow valve does not open. The 757 has two AUTO controllers, and also has a MANUAL mode. Interestingly enough, I decided to dig through the CFM and there really is no guidance in either the CFM or the QRH for an overpressure situation. I can find no EICAS messages that deal with it, with the exception of " <font color="yellow">CABIN AUTOMATIC INOPERATIVE</font>" , which means that the Auto 1 and Auto 2 cabin altitude control functions are inoperative or the cabin altitude selector is in manual. Can any other 757/767 people find it in their books? |
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March 17th, 2004, 17:15
| #4 |
| Junior Member  Join Date: Jun 2003 Location: CA
Posts: 85
| Re: Overpressurization?? i don't know.. i'm studying the lear...it's bulletproof !  |
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March 17th, 2004, 20:09
| #5 |
| Senior Member  Join Date: Oct 2003 Location: DXR, Connecticut
Posts: 1,170
 | Re: Overpressurization?? the 172 I fly is always overpressurized, with all the hot air coming out of my instructor's mouth. |
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March 17th, 2004, 22:23
| #6 |
| Senior Member  Join Date: Feb 2003 Location: Orange County
Posts: 336
| Re: Overpressurization?? [ QUOTE ] the 172 I fly is always overpressurized, with all the hot air coming out of my instructor's mouth. [/ QUOTE ] lol. I looked for a little, I couldn't find anything on the valves, it might not have to do with anything special, just valves located somewhere, where if too much pressure builds up, it blows them open, and then a light goes on in the cockpit notifying the pilots of it. Just a guess though. |
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March 17th, 2004, 22:35
| #7 |
| Old Skool Join Date: Dec 2002 Location: Utopia
Posts: 12,503
| Re: Overpressurization?? [ QUOTE ] I looked for a little, I couldn't find anything on the valves, it might not have to do with anything special, just valves located somewhere, where if too much pressure builds up, it blows them open, and then a light goes on in the cockpit notifying the pilots of it. Just a guess though. [/ QUOTE ] This talks about it a little bit... 737 System |
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March 18th, 2004, 07:33
| #8 |
| Old Skool  Join Date: Nov 2001 Location: DFW
Posts: 7,143
| Re: Overpressurization?? [ QUOTE ] i don't know.. i'm studying the lear...it's bulletproof ! [/ QUOTE ] Tell Payne Stewart that.  |
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March 18th, 2004, 10:20
| #9 |
| Junior Member  Join Date: Jun 2003 Location: Cali
Posts: 194
| Re: Overpressurization?? Remind us, what happened again? was it an overpressurized condition? I could go to the website, but I am too f--g lazy today.... |
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March 18th, 2004, 10:33
| #10 |
| Senior Member  Join Date: Jan 2003 Location: Low Earth Orbit
Posts: 1,354
| Re: Overpressurization?? The Payne Stewart accident wasn't overpressurization, it was no pressurizarion. |
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March 18th, 2004, 10:39
| #11 |
| Old Skool Join Date: Dec 2002 Location: Utopia
Posts: 12,503
| Re: Overpressurization?? I think he was referencing the statement about the Learjet being bulletproof.... |
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March 18th, 2004, 11:09
| #12 |
| Newbie Join Date: Apr 2003
Posts: 28
| Re: Overpressurization?? I'm looking at the checklist for a LR-55 and it says: 1. Pressurization AUTO-MAN Switch--MAN (switch to manual instead of automatic) 2. UP-DN Manual Control--UP as required (to get a higher cabin altitude by manually opening the outflow valve) 3. One BLEED AIR Switch--OFF 4. Adjust power on the opposite engine to control pressurization. (less power, less bleed air, less pressurizaton) |
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March 18th, 2004, 11:11
| #13 |
| Old Skool Join Date: Nov 2001 Location: DFW
Posts: 7,143
| Re: Overpressurization?? [ QUOTE ] I think he was referencing the statement about the Learjet being bulletproof.... [/ QUOTE ] Hammer/Nail. |
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March 18th, 2004, 11:28
| #14 |
| Junior Member Join Date: Jun 2003 Location: Cali
Posts: 194
| Re: Overpressurization?? No, actually I wanted to have some details on the accident... You said it was no pressurization, what caused it? |
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March 18th, 2004, 11:31
| #15 |
| Old Skool Join Date: Nov 2001 Location: DFW
Posts: 7,143
| Re: Overpressurization?? I didn't say is was or wasn't anything.  But, to answer your question, the case is still ongoing, but so far as my knowledge of it goes (my old firm was handling the case for Lear), it was a case of rapid decompression. |
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March 19th, 2004, 19:52
| #17 |
| Old Skool  Join Date: May 2003 Location: In the O-zone
Posts: 5,807
 | Re: Overpressurization?? This outspoken guy in our Midway ground school claimed that dry ice was responsible for the Payne Stewart crash. We all laughed at him. Imagine my chagrin when I found out from some of the investigators here in Orlando that there were two large coolers of dry ice on the plane (they were going fishing.) It is possible, they said, that they never lost pressurization, but just ran out of oxygen and passed out. I said "But I thought the chase fighters saw the windows iced up?" Their reply, "Since the Lear 35 operators normally climb in IAS mode, they did not main a steady altitude and it is possible that the altitude oscillations they experienced (between 35,000 and 53,000 ft) could have caused water vapor to freeze on the inside of the windows. This normally happens at altitude anyway." My reply was "Huh!" I learned something that day. |
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March 20th, 2004, 18:16
| #18 |
| Junior Member Join Date: Jun 2003 Location: Cali
Posts: 194
| Re: Overpressurization?? Thanks for that, I didn't follow up on the accident, and I didn't remember the circumstances... However, interesting point about the dry ice... |
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March 22nd, 2004, 09:18
| #19 |
| Old Skool Join Date: Nov 2001 Location: DFW
Posts: 7,143
| Re: Overpressurization?? [ QUOTE ] This outspoken guy in our Midway ground school claimed that dry ice was responsible for the Payne Stewart crash. We all laughed at him. Imagine my chagrin when I found out from some of the investigators here in Orlando that there were two large coolers of dry ice on the plane (they were going fishing.) It is possible, they said, that they never lost pressurization, but just ran out of oxygen and passed out. [/ QUOTE ] So far as my knowledge of the case from sitting in the office next to the attorneys who were working on the case and being privy to seeing some of the research..... that outspoken guy was wrong. It "could have" been a factor - but wasn't. |
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March 30th, 2004, 21:35
| #20 |
| Newbie Join Date: Oct 2002
Posts: 4
| Re: Overpressurization?? Hi... As indicated in the NTSB final report, (and by R2F), there was no dry ice on board this aircraft. Quite a few interesting details discovered during the investigation, however. Here's a link if you're interested. Regards NTSB Accident Publication |
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