austinairport
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"Plane Won't Pressurize"

Thu Feb 22, 2007 8:19 am

On a recent trip to Norfolk we were told that the "Plane won't Presurrise" after 2 1/2 hours of flying at 10,000ft. we landed at Nashville. I was just wondering if this happens often, if ever. We arrived in Austin later that night.
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OPNLguy
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"Plane Won't Pressurize"

Thu Feb 22, 2007 8:29 am

Do I have this right? You were going to ORF but landed in BNA, but also ended up in AUS later that night?

There are several reasons why an aircraft might not be able to pressurize, but a major one is that an outflow valve fails in the open position. Both airconditioning packs will work fine, and pump air into the cabin, but it comes out via the outflow valve at too high a rate to maintain pressurization. Most pressurization problems (when they do actually occur) involve one of the two airconditioning packs, and with one inop that usually involves limiting the max altitude to 24,000 or 25,000 feet. (That's for a 737; other aircraft may be different). Having a pressurization problem that requires UNpressurized flight at 9,000 or 10,000 feet is alot more rare an occurence.

If you can confirm the city-pair and the aircraft type, I can try to fine-tune my guess... Wink
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
austinairport
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"Plane Won't Pressurize"

Thu Feb 22, 2007 8:31 am

My bad. I was going back home to Austin.  Yeah sure
Whoever said you can do anything you set your mind to has obviously never tried to slam a revolving door!!!
 
OPNLguy
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"Plane Won't Pressurize"

Thu Feb 22, 2007 8:35 am

OK, so ORF-BNA-AUS? Aircraft type? Was it the same aircraft from BNA-AUS as it was ORF-BNA?
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
austinairport
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RE: "Plane Won't Pressurize"

Sun Mar 04, 2007 2:15 pm

AUS-DFW-ORF wen't fine. ORF-DFW is when we saw the real problems. After 10 minutes in flight we noticed the heat. Then the captain came on the intercom and said that the plane wouldn't pressurise. So he lowered the flaps and eased up on the throttle to help burn off some fuel. He then told us that we were going to land in Nashville (BNA). We sat there in BNA for 2 hours helpless and not knowing what was going to happen. So then we got on a Replacement MD-80 (that was the original type of aircraft). Most people had found another flight to their destination so there was about 60 people on the plane. We arrived in Dallas to find out that our connecting flight to Austin was also delayed so we didn't have to spend the night in Dallas. We arrived in Austin at about 12:30pm.
Whoever said you can do anything you set your mind to has obviously never tried to slam a revolving door!!!
 
N1120A
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RE: "Plane Won't Pressurize"

Sun Mar 04, 2007 2:23 pm

Quoting AustinAirport (Reply 4):
We arrived in Dallas to find out that our connecting flight to Austin was also delayed so we didn't have to spend the night in Dallas. We arrived in Austin at about 12:30pm.

Why would you have to spend the night in Dallas if you were on a flight that arrived AUS just past noon? Do you mean 12:30 AM?
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austinairport
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RE: "Plane Won't Pressurize"

Sun Mar 04, 2007 2:28 pm

Why would you have to spend the night in Dallas if you were on a flight that arrived AUS just past noon? Do you mean 12:30 AM?

My Bad
 Yeah sure
Whoever said you can do anything you set your mind to has obviously never tried to slam a revolving door!!!
 
AAR90
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RE: "Plane Won't Pressurize"

Sun Mar 04, 2007 4:14 pm

Quoting AustinAirport (Reply 4):
After 10 minutes in flight we noticed the heat.

What "heat"??? Temperature has virtually nothing to do with pressurization.

Quote:
Then the captain came on the intercom and said that the plane wouldn't pressurise. So he lowered the flaps and eased up on the throttle to help burn off some fuel.

This makes no sense. Extending flaps and retarding throttle are NOT how one increases fuel flow. Please provide flight number(s) and date(s) and I'll see if I can find out anything more specific.
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Silver1SWA
Crew
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RE: "Plane Won't Pressurize"

Sun Mar 04, 2007 4:33 pm

I worked a flight back when I was at SJC that flew to LAX with a planned cruise altitude of 10,000 feet for the exact same reason.
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
durangomac
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RE: "Plane Won't Pressurize"

Sun Mar 04, 2007 4:48 pm

I was working one evening and we had a Dash-8 loose pressure on descent into DRO because of the pressure seal on the main cabin door lost pressure due to a faulty part. The good part was the fact they were already about 15,000 feet and only minutes away from landing.
 
S5FA170
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RE: "Plane Won't Pressurize"

Sun Mar 04, 2007 9:59 pm

I worked a flight from SAT-JFK that failed to pressurize on climbout (my understanding is both bleeds failed. one was deferred and the other failed on climbout.)

I had just begun First Class service when I felt myself get lightheaded. As I was reaching for my jumpseat, the FO got on the PA and told the passengers that the aircraft failed to pressurize and we'd be returning to SAT. After two hours of circling SAT with the flaps down and gear down (noisy!), we landed. The flight was cancelled and we ferried the airplane to CMH at 10,000 feet. It took forever!
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austinairport
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RE: "Plane Won't Pressurize"

Mon Mar 05, 2007 8:04 am

I'm saying it was hotter than hell on the d*** plane.
Whoever said you can do anything you set your mind to has obviously never tried to slam a revolving door!!!
 
AAR90
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RE: "Plane Won't Pressurize"

Mon Mar 05, 2007 10:57 am

Flight number and date please.
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thegreatchecko
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RE: "Plane Won't Pressurize"

Mon Mar 05, 2007 4:08 pm

Sounds like the outflow valves decided not to work that day. I've had them freeze shut, but that probably had more to do with the outside ambient temps and the humidity than anything else. This is Alaska!

Quoting AustinAirport (Reply 11):
I'm saying it was hotter than hell on the d*** plane.

they may have had to shut down the cooling packs due to the failure. I'm sure a mad dog driver might be able to shine some more light on the temperature situation.

Quoting AAR90 (Reply 7):

What "heat"??? Temperature has virtually nothing to do with pressurization.

Actually, heat has everything to do with pressurization. The aircraft is pressurized using bleed air off the engines which is of higher pressure than ambient and also very warm.

On the B1900, we heat the plane using bleed air and we can get it pretty darn hot. We control the temperature using a valve that bypasses the warm uncooled air by the cooling system and mixes it with the cooled air. Aircraft use various means to cool the air down to more survivable temps.

Most trasport category aircraft use air cycle machines. ACM's in my opinion are quite amazing pieces of machinery and can be quite complicated in design, but work on a very simple premise.

An ACM forces the air to work, nothing more. Since the air is a closed system, ie no energy is being added, it has to use some of its potential energy, which at the time some is in the form of heat, to work. It is also important to note that energy cannot be created or destroyed, it can only be transfered, see Newton about those laws.

The air goes to work, usually spinning a turbine, and the temperature is lowered as energy is transfered to the turbine.

Got to love science!

Checko
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AAR90
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RE: "Plane Won't Pressurize"

Mon Mar 05, 2007 9:35 pm

Quoting TheGreatChecko (Reply 13):
Actually, heat has everything to do with pressurization. The aircraft is pressurized using bleed air off the engines which is of higher pressure than ambient and also very warm.

Correct; however, if the temp controls for both A/C systems failed the plane would still pressurize. In that case I would tell the passengers THE TRUTH.... the air conditioning temp controls have failed, I have no control over the temperature in the cabin and we are going to....(fill in the blank). I would NOT say the "plane won't pressurize" as that is not true. OTOH, if the outflow valve failed (unlikely as the MD80 has a direct cable control wheel in cockpit and you test it before flight) then you have a pressurization problem and the "plane won't pressurize." But if that was the case, the cabin should not have gotten hot (one or both packs still working)... certainly not within 10 minutes of takeoff.

FWIW, if either of these scenarios had happened to a flight I was flying ORF-DFW, I would NOT have flown all the way to BNA. There are too many other stations nearby that could handle the 130 or so pax. And one does not lower flaps and _retard_ the throttle in order to "help burn off some fuel" (extending the gear works though). These inconsistencies indicate that actual events may not have transpired as described and has my curiosity. Which is why I continue to ask for the flight number & date. It would be interesting to read what actually happened.
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