SWA Rapid Decompression
04-02-2011, 06:05 PM
#52
veut gagner à la loterie
Joined APC: Apr 2008
Position: Light Chop
Posts: 23,286
Its called cycles you junior PhD aero experts....SWA flies way more cycles per month on a jet than most airlines I surmise.
I fly them and I used to build em so ...hmmm.
Would take a Boeing over a Airbus any day for durability. No....757 and 737 dont share a common fuselage barrel ...d'oh.
Calm down and say " aging aircraft issues". Good thing the who section didnt peel back ala Alaska 737.
Let the OEM and NTSB do their work folks and breath easy.
Jet Driver
I fly them and I used to build em so ...hmmm.
Would take a Boeing over a Airbus any day for durability. No....757 and 737 dont share a common fuselage barrel ...d'oh.
Calm down and say " aging aircraft issues". Good thing the who section didnt peel back ala Alaska 737.
Let the OEM and NTSB do their work folks and breath easy.
Jet Driver
Did Alaska have a 737 have the top peel back too?
And my understanding is that the 757 utilizes the same upper-fuselage diameter as the 707, 727, and 737.
Last edited by forgot to bid; 04-02-2011 at 06:18 PM.
04-02-2011, 06:05 PM
#53
Day puke
Joined APC: Feb 2006
Position: Out.
Posts: 3,865
Bravo Zulu to the whole crew, cockpit and cabin.
Now for the question...
I thought one tiny bullet hole would lead to everybody getting sucked out ... like in the movies
According to one report, it took some 45 seconds for the masks to drop. I'm guessing they drop around cabin alt of 15,000. So, by my calculation a 3ish square foot hole results in a cabin rate of climb of roughly 10,000 fpm? Does that sound reasonable?
I'm trying to imagine what it felt like.
Now for the question...
I thought one tiny bullet hole would lead to everybody getting sucked out ... like in the movies
According to one report, it took some 45 seconds for the masks to drop. I'm guessing they drop around cabin alt of 15,000. So, by my calculation a 3ish square foot hole results in a cabin rate of climb of roughly 10,000 fpm? Does that sound reasonable?
I'm trying to imagine what it felt like.
04-02-2011, 06:08 PM
#54
Che Guevara
Joined APC: Aug 2005
Posts: 6,408
I believe that issue was a design flaw of the body. Something about how the rivets were all in a line so when part of it started to go it ripped right down them like a zipper. After that I think they started staggering the rivets to keep that from happening. Someone who flies a 73 go take a look!
04-02-2011, 06:13 PM
#55
Che Guevara
Joined APC: Aug 2005
Posts: 6,408
04-02-2011, 06:24 PM
#56
veut gagner à la loterie
Joined APC: Apr 2008
Position: Light Chop
Posts: 23,286
04-02-2011, 06:40 PM
#57
Gets Weekends Off
Joined APC: Aug 2008
Position: 777 Left
Posts: 347
Its called cycles you junior PhD aero experts....SWA flies way more cycles per month on a jet than most airlines I surmise.
I fly them and I used to build em so ...hmmm.
Would take a Boeing over a Airbus any day for durability. No....757 and 737 dont share a common fuselage barrel ...d'oh.
Calm down and say " aging aircraft issues". Good thing the who section didnt peel back ala Alaska 737.
Let the OEM and NTSB do their work folks and breath easy.
Jet Driver
I fly them and I used to build em so ...hmmm.
Would take a Boeing over a Airbus any day for durability. No....757 and 737 dont share a common fuselage barrel ...d'oh.
Calm down and say " aging aircraft issues". Good thing the who section didnt peel back ala Alaska 737.
Let the OEM and NTSB do their work folks and breath easy.
Jet Driver
The 737 and 757 do use the same fusalage top. Just checked. All Boeing narrows do.
The 757 that American had pop a hole is not running the SWA cycle count per day...... But still blew out.
I didnt know UAL had a 75 rip, but if it is true, that just adds to the mystery of Boeing narrow pops.
I am not trying to bash Boeing, I fly for a living and if it is a Bus, MD or Boeing, I don't really care, as long as I am payed to fly them, I will and love my job. But it is pretty clear that Boeing has an issue with rips and holes in these birds that are aged.
320's are running short hops for several airlines and have been for years. The DC-9's at NWA (okay DAL) have WAY more cycles than any 737 at SWA and the American MD-80's are certainly up there as well.
I also agree that SWA maint needs to be looked at, but the bigger issue seems to be Boeing narrows blowing holes and getting rips when they should not be if they are still in their service lives.
The SWA crew did their job and did it well. But they shouldnt have to worry about the top blowing open and it seems that the 757 and 737 has a problem when they are about 15+ years.
I do not know the answer as to why, but I can certainly look at the last three years and see there is a problem that if age is a cause, will only worsen with time and cycles for the 73 and 75.
04-02-2011, 06:49 PM
#59
Gets Weekends Off
Joined APC: Mar 2011
Posts: 115
When structural damage is suspected, you typically get pretty slow to keep from making it worse.
However...FlightAware is not too accurate in regards to just about anything, so I wouldn't trust any airspeed indications from it, especially if they're one off speeds (ie 230, 231, 229, 155, 180, 230, 230) as it's all radar-derived data.
In the FlightAware Track Log from that flight, the speeds where you pointed out are 225, 139, 190, 234. I don't know that a 737 could even go from 225-139 then back to 234 in the space of 4 minutes, and even if it could, slowing all the way to 140 for a few seconds just to accelerate back up wouldn't be enough time to check for structural damage then decide it's safe to accelerate again. I'd say FlightAware bug.
You can see the groundspeeds are 230 or lower for the rest of the flight after the descent, so they were tracking a little slower than normal probably just to play it safe.
However...FlightAware is not too accurate in regards to just about anything, so I wouldn't trust any airspeed indications from it, especially if they're one off speeds (ie 230, 231, 229, 155, 180, 230, 230) as it's all radar-derived data.
In the FlightAware Track Log from that flight, the speeds where you pointed out are 225, 139, 190, 234. I don't know that a 737 could even go from 225-139 then back to 234 in the space of 4 minutes, and even if it could, slowing all the way to 140 for a few seconds just to accelerate back up wouldn't be enough time to check for structural damage then decide it's safe to accelerate again. I'd say FlightAware bug.
You can see the groundspeeds are 230 or lower for the rest of the flight after the descent, so they were tracking a little slower than normal probably just to play it safe.
04-02-2011, 06:58 PM
#60
veut gagner à la loterie
Joined APC: Apr 2008
Position: Light Chop
Posts: 23,286
Well, this thread has been moved. Which means it will shortly die. So in parting:
A319/A320/A321 - 48,000 cycles
B727 - 60,000 cycles
B777 - 40,000 cycles
B737 - 75,000 cycles
DC9 - 100,000 cycles extended to 115-120K cycles
MD80 - 50,000 cycles
Now, from page 14 of the 222 page NTSB report on Aloha 243 says something interesting about cycles:
So not every cycle is a full cycle. If SWA truly banged this one in and out on short runs it's completely possible it did not hit it's full cycles so to say it had XYZ cycles may be misleading as far as the NTSB would be concerned.
Also, and this is rather unfortunate but interesting if true:
source: The Honolulu Advertiser | Local News
A319/A320/A321 - 48,000 cycles
B727 - 60,000 cycles
B777 - 40,000 cycles
B737 - 75,000 cycles
DC9 - 100,000 cycles extended to 115-120K cycles
MD80 - 50,000 cycles
Now, from page 14 of the 222 page NTSB report on Aloha 243 says something interesting about cycles:
At the time of the accident, the N73711 had accumulated 35,496 flight hours and 89,680 flight cycles (landings), the
second highest number of cycles in the worldwide B-737 fleet. Due to the short distance between destinations on
some Aloha Airlines routes, the maximum pressure differential of 7.5 psi was not reached on every flight.
Therefore, the number of equivalent full pressurization cycles on the accident airplane is significantly less than the
89,680 cycles accumulated on the airplane.
second highest number of cycles in the worldwide B-737 fleet. Due to the short distance between destinations on
some Aloha Airlines routes, the maximum pressure differential of 7.5 psi was not reached on every flight.
Therefore, the number of equivalent full pressurization cycles on the accident airplane is significantly less than the
89,680 cycles accumulated on the airplane.
Also, and this is rather unfortunate but interesting if true:
Boeing says the 737 was designed to decompress safely with as much as a 40-inch crack in the plane’s skin, the 0.036-inch thick, aluminum outer layer of the fuselage. Instead of an explosive decompression, the hole in the skin is supposed to release internal pressure in a controlled way. In the Aloha accident, investigators concluded that more damage occurred — about 18 feet of the fuselage tore away — because many fatigue-caused cracks had gone undetected.
Austin says that a weakened fuselage was not the main reason for the extensive damage.
A 10-inch-by-10-inch hole opened, he says, in the roof of the cabin at a location known as body station 500. (Body stations are points on the fuselage that are measured in inches from near the nose of the jet to the rear.) A powerful stream of air swept an Aloha flight attendant off her feet and toward the hole, Austin says. Her head and right arm went through the hole, he says, but her body momentarily plugged it, blocking the escaping air and creating a jolt of pressure that ripped the jet apart. The flight attendant was swept out, and her body was never found.
Austin says that a weakened fuselage was not the main reason for the extensive damage.
A 10-inch-by-10-inch hole opened, he says, in the roof of the cabin at a location known as body station 500. (Body stations are points on the fuselage that are measured in inches from near the nose of the jet to the rear.) A powerful stream of air swept an Aloha flight attendant off her feet and toward the hole, Austin says. Her head and right arm went through the hole, he says, but her body momentarily plugged it, blocking the escaping air and creating a jolt of pressure that ripped the jet apart. The flight attendant was swept out, and her body was never found.
Thread
Thread Starter
Forum
Replies
Last Post
