Doomed US Air Jet Under Investigation

Geico266

Geico266

Touchdown! Greaser!
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Geico
Giraldo Rivera & Fox News is reporting the NTSB reports the same jet that crash landed into the Hudson suffered an "inflight compressor stall" the Tuesday before it "landed" in the Hudson.

What causes an inflight compressor stall? Can it be related to the engine outs if birds were not the cause?
 
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Geico...it was actually a USAir jet...
 
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It was US Airways. It did have compressor stalls, but they relit the engine and continued the flight. MX returned the plane to service after it landed in CLT with a clean bill of health. Prior compressor stalls or not, sucking a bunch of big birds into an engine will kill it. It's an old story, and a non-story IMHO.

Compressor stalls can be a big deal if they're allowed to continue, but if the engine is secured quickly and no limitations are exceeded they're not that big of a deal at all. We have a few planes that have had a compressor stall and are still flying with no further trouble.
 
Teller1900 said:
It was US Airways. It did have compressor stalls, but they relit the engine and continued the flight. MX returned the plane to service after it landed in CLT with a clean bill of health. Prior compressor stalls or not, sucking a bunch of big birds into an engine will kill it. It's an old story, and a non-story IMHO.

Compressor stalls can be a big deal if they're allowed to continue, but if the engine is secured quickly and no limitations are exceeded they're not that big of a deal at all. We have a few planes that have had a compressor stall and are still flying with no further trouble.
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What causes them? Is it maintenance, mechanical, or flying technique?
 
If you are an AOPA member, there is a detailed description of compressor stalls in the Never Again section
 
Geico266 said:
Got it! Correction is on the way. Thank you mods!

What causes a compressor stall?
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The most common reason for them...

The axial compressors are basically a disk with a bunch of really small fan blades on it. The compressor disks rotate between stator vanes (almost identical fan blades that are fixed to the outer ring of the engine between the axial compressors). A compressor stall occurs when air doesn't move between the compressor disks and the stator vanes smoothly and the blades stall, just like a wing.

The failure on the afternoon that the Bus ended up in the water would have technically been a compressor stall...the birds choked off the air supply to the compressor section, causing it to stall and stop sucking in air, basically.

Clear as mud? I'm clearly not an engineer, but you can read a much better explanation here.
 
And I imagine it wasn't the comp stall itself that caused the shutdown on the flight prior to the crash, it may have been the computer shutting the motor down to prevent damage. I'm not sure I'd like the computer making the decision to shut down an engine or not. Those are the kind of things that, in my not very humble opinion, should be left up to the crew to decide. If the EGT is shooting up, pull the power back, but PLEASE do not just shut the engine off. It may recover from the stall without any further action.

On a side note, have any of you turbine folks ever had a comp stall on the takeoff roll? Whaddya do about it? I've had one and we aborted the T/O. Just curious what others do.
 
Geico266 said:
Is it odd to anyone else but me the pilot & crew have not spoken publically yet? You would think the pilot would be welcome on every news show around. I can understand him wanting to avoid that, but a select few might be good for aviation.
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I'm sure the whole crew would be more than welcome on any news show, but as with any official investigation it's best to keep quiet until the investigators are done. Chances are the Union, the airline, and the crew themselves have been doing as much as they can to stay away from cameras until the NTSB has finished their report. And I'd assume US Air has a clause similar to ours about not talking to the press at all about anything company related without clearing it through HQ first. If the media is still interested in the story when the NTSB is done with their investigation I'm sure we'll hear plenty from the crew and/or airline then.
 
Teller1900 said:
I'm sure the whole crew would be more than welcome on any news show, but as with any official investigation it's best to keep quiet until the investigators are done. Chances are the Union, the airline, and the crew themselves have been doing as much as they can to stay away from cameras until the NTSB has finished their report. And I'd assume US Air has a clause similar to ours about not talking to the press at all about anything company related without clearing it through HQ first. If the media is still interested in the story when the NTSB is done with their investigation I'm sure we'll hear plenty from the crew and/or airline then.
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Sorry, I deleted my post before you posted yours after reading an article that stated what you said. I guess I'm just anxious to hear the "rest of the story". From all accounts they really did an exceptional job of "flying the airplane".
 
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Geico266 said:
Sorry, I deleted my post before you posted yours. I read an article that stated what you said here. I guess I'm just anxious to hear the "rest of the story". From all accounts they really did a good job.
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I'm just too quick for ya :rofl:. One of my sim partners from the Beech was on the flight, and I don't think he could've been much happier about the outcome! I'm sure someone will get a book deal, or at least a few good interviews when the NTSB is all done. Not to mention, I'm sure the NTSB report will be a good read, too!
 
AWACSEng said:
And I imagine it wasn't the comp stall itself that caused the shutdown on the flight prior to the crash, it may have been the computer shutting the motor down to prevent damage. I'm not sure I'd like the computer making the decision to shut down an engine or not. Those are the kind of things that, in my not very humble opinion, should be left up to the crew to decide. If the EGT is shooting up, pull the power back, but PLEASE do not just shut the engine off. It may recover from the stall without any further action.

On a side note, have any of you turbine folks ever had a comp stall on the takeoff roll? Whaddya do about it? I've had one and we aborted the T/O. Just curious what others do.
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The Airbus won't shut it down automatically for a compressor stall/surge. Like you said, the memory item is "Thrust Lever.....Idle" and then accomplish the rest or the procedure. I don't know of any aircraft that would shut it down automatically.

I've had several compressor stalls in cruise but never any on takeoff. If it happens prior to V1, you reject the takeoff, after V1, you continue the takeoff and treat it there. Simple.
 
maddog52 said:
The Airbus won't shut it down automatically for a compressor stall/surge. Like you said, the memory item is "Thrust Lever.....Idle" and then accomplish the rest or the procedure. I don't know of any aircraft that would shut it down automatically.

I've had several compressor stalls in cruise but never any on takeoff. If it happens prior to V1, you reject the takeoff, after V1, you continue the takeoff and treat it there. Simple.
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That's about what I figured. I was thinking that since the 'bus seems to not like the crew making decisions that it may shut the engine down based on the abnormally high EGT that is usually associated with the stall. At least they (the manufacturers) got that right. I agree with your assessment of the stall on T/O. I mainly put the question out there to see if other folks see a comp stall as a less serious event.
 
AWACSEng said:
I was thinking that since the 'bus seems to not like the crew making decisions that it may shut the engine down based on the abnormally high EGT that is usually associated with the stall.
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The engine doesn't shut itself down for anything on an Airbus.
 
Greg Bockelman said:
The engine doesn't shut itself down for anything on an Airbus.
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Good to know. We were having a table top discussion about this at work today and this possibility came up. Must be an urban ledgend spread by the Airbus nay-sayers.
 
AWACSEng said:
On a side note, have any of you turbine folks ever had a comp stall on the takeoff roll? Whaddya do about it? I've had one and we aborted the T/O. Just curious what others do.
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The B727 will compressor stall on #2 engine during the takeoff roll if you have a real stiff 90 degree crosswind. The best way to avoid that is advance #1 and #3 start the roll then bring #2 up smoothly once speed builds up around 60kts.
 
Rotor&Wing said:
The B727 will compressor stall on #2 engine during the takeoff roll if you have a real stiff 90 degree crosswind. The best way to avoid that is advance #1 and #3 start the roll then bring #2 up smoothly once speed builds up around 60kts.
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Is this a design "flaw"? I mean could the #2 engine have been mounted higher on the VS to get cleaner air? Just curious.
 
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Rotor&Wing said:
The B727 will compressor stall on #2 engine during the takeoff roll if you have a real stiff 90 degree crosswind. The best way to avoid that is advance #1 and #3 start the roll then bring #2 up smoothly once speed builds up around 60kts.
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I've had that happen to me, just as you describe. The crosswind upsets the airflow going into #2, causing turbulence in the inlet and a compressor stall was the result.

We had rolled less than 100 feet for takeoff when it happened, so there was no drama associated with the rejected takeoff. :sleep: We taxied to a runway that was better aligned with the wind, and power came up on #1 and #3. Deep in the roll power came up on #2. Smooth flight thereafter.

-Skip
 
Greg Bockelman said:
The engine doesn't shut itself down for anything on an Airbus.
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AWACSEng said:
Good to know. We were having a table top discussion about this at work today and this possibility came up. Must be an urban ledgend spread by the Airbus nay-sayers.
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The APU will shut itself down automatically for a certain set of circumstances. Basically that is because an APU may/will be running when no one is on the plane to monitor it. But the engines don't have that capability, nor should they.
 
Geico266 said:
Is this a design "flaw"? I mean could the #2 engine have been mounted higher on the VS to get cleaner air? Just curious.
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I don't think so. It is the crosswind that causes the air to come into the inlet "sideways" (not down the centerline) that is the problem. Interference from the fuselage doesn't seem to be a problem.

-Skip
 
Skip Miller said:
I don't think so. It is the crosswind that causes the air to come into the inlet "sideways" (not down the centerline) that is the problem. Interference from the fuselage doesn't seem to be a problem.

-Skip
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As best I understand it that's (basically) the same reason the F-14 had so much trouble maneuvering with its original F-111 P&W engines, and the reason the F-15 has the variable geometry engine inlets. At high speed and high AOA maneuvering, the air was turbulent and coming into the engine "sideways," causing compressor stalls. In the case of the F-14, when they put the new GE engines on, they had a lot less crashes due to compressor stalls.
 
Greg Bockelman said:
The APU will shut itself down automatically for a certain set of circumstances. Basically that is because an APU may/will be running when no one is on the plane to monitor it. But the engines don't have that capability, nor should they.
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I knew APUs shut themselves off. Ours does the same thing. I'm glad the speculation on the computer having that kind of authority over the engines was just that, speculation. Thanks for the enlightenment!
 
As the gallows humor develops on this: Some light has been shed on why the captain returned to the plane twice <g>. Evidently there were free drink coupons in the cockpit (didn't want to be charged for the water landing.). Plenty of ice out on the wing.

Best,

Dave
 
Teller1900 said:
I hear that on 8 Feb, 60 Minutes is going to have the whole crew on.
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Oh great. Don't get me wrong, of course they did a good job, but making such a big deal out of it is just going to reinforce the public's perception of flying as a game of luck, or chance, and it ultimately does a disservice to all the good pilots flying out there.

-Felix
 
sba55 said:
Oh great. Don't get me wrong, of course they did a good job, but making such a big deal out of it is just going to reinforce the public's perception of flying as a game of luck, or chance, and it ultimately does a disservice to all the good pilots flying out there.

-Felix
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You knew it was going to happen. Just roll with it.:smile:
 
Teller1900 said:
I hear that on 8 Feb, 60 Minutes is going to have the whole crew on.
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The pilot (Skully) was interviewed for the first time today and I caught a part of it. "Just doing the job I was trained to do" was all I heard. I sure would like to shake his hand someday.


I hope if I ever have an engine out I'm near water. :yikes: :nono:

:rofl:
 
Geico266 said:
The pilot (Skully) was interviewed for the first time today and I caught a part of it. "Just doing the job I was trained to do" was all I heard. I sure would like to shake his hand someday.
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The cockpit crew on that plane would never get close to buying their own drinks in our crowd...

Geico266 said:
I hope if I ever have an engine out I'm near water. :yikes: :nono:

:rofl:
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I hope that, if I ever have an engine-out, I'm near a big, wide runway! :D
 
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