Flying Home Commericially Tonite...

.... had a front row seat (actully it was an exit row window seat...) for a
compressor stall on an America West Airbus while departing Detroit enroute
home to Phoenix.

Just after liftoff we heard/felt a moderate "bang" and I glimsed some flame
out the back of the left engine just about the time the gear was in transit.
Captain came on the I/C and said it was due to wake turbulence from the
Northwest Airlines aircraft that departed ahead of us.

Flight continued to Phoenix without any further issues.

Pretty interesting when you momentarilly take "suck" out of the "Suck ...
Squeeze ... Bang ... Blow" chain.

Am I correct in thinking that disrupting the airflow into a turbofan engine
sets up a momentarilly over-rich mixture (hence the visible flame?)

Jay Beckman
PP-ASEL
AZ Cloudbusters
Chandler, AZ

"Jay Beckman" wrote in message
news:08tsf.9585$xF6.1071@fed1read01...
... had a front row seat (actully it was an exit row window seat...) for a
compressor stall on an America West Airbus while departing Detroit enroute
home to Phoenix.

Just after liftoff we heard/felt a moderate "bang" and I glimsed some
flame out the back of the left engine just about the time the gear was in
transit. Captain came on the I/C and said it was due to wake turbulence
from the Northwest Airlines aircraft that departed ahead of us.

Did you feel some turbulance?


Flight continued to Phoenix without any further issues.

Pretty interesting when you momentarilly take "suck" out of the "Suck ...
Squeeze ... Bang ... Blow" chain.

Ummm...that doesn't apply to turbines....at least not as a discrete
sequence.


Am I correct in thinking that disrupting the airflow into a turbofan
engine sets up a momentarilly over-rich mixture (hence the visible flame?)

MTL.

Matt Barrow wrote:
"Jay Beckman" wrote in message
news:08tsf.9585$xF6.1071@fed1read01...

... had a front row seat (actully it was an exit row window seat...) for a
compressor stall on an America West Airbus while departing Detroit enroute
home to Phoenix.

Just after liftoff we heard/felt a moderate "bang" and I glimsed some
flame out the back of the left engine just about the time the gear was in
transit. Captain came on the I/C and said it was due to wake turbulence
from the Northwest Airlines aircraft that departed ahead of us.


Jet engines do sort of have the suck/squeeze/bang/blow but it's all a
continuous action. Check out the link below for a slightly more
detailed view. Compressor stalls can be nasty as pressurized combustion
gasses going the wrong way can in some instances damage the engine.

I don't think it's so much of an over rich mixture causing the problem
as it is the flames going the wrong way or burning in such a way that
they aren't producing a lot of air pressure to spin the turbine at the
outlet end of the engine.

http://www.grc.nasa.gov/WWW/K-12/air...bpar/ente.html

"Jay Beckman" wrote in message
news:08tsf.9585$xF6.1071@fed1read01...
... had a front row seat (actully it was an exit row window seat...) for a
compressor stall on an America West Airbus while departing Detroit enroute
home to Phoenix.

Just after liftoff we heard/felt a moderate "bang" and I glimsed some
flame out the back of the left engine just about the time the gear was in
transit. Captain came on the I/C and said it was due to wake turbulence
from the Northwest Airlines aircraft that departed ahead of us.

Flight continued to Phoenix without any further issues.

Good guess, as to the rich. No air was going through, but I'll bet that
fuel was.

I was on a flight that must have been the first landing of the first
captain's sisters kid, who had never landed anything before. It was
overcorrected all of the way down, landed long, and when he put the thrust
reversers up and gunned it, it stalled, not once, but twice.

My only experience with them, however.
--
Jim in NC

A few years ago, before I started flying, I was on an American flight
out of Houston with a pretty good crosswind ripping across the runway.
I was seated near the back of the plane. A couple of seconds after
takeoff we heard a VERY loud bang, the left wing dipped momentarily,
and we continued on...

About 20 minutes later the captain came on and explained they had a
compression stall due to, he said, to the wind blowing across the
engine. He apologized for waiting so long to explain it, but he said
he and the crew were busy going through the manual for the restart
procedure.

Not being a pilot at the time, I remember thinking that maybe he should
have read the manual BEFORE flying the plane :-)

If it's really true that the crosswind caused the compression stall, I
wonder why we don't hear about a double stall very often. Theoretically, the
wind can be strong enough to affect both engines, no?

Marco Leon

"Wiz" wrote in message
oups.com...
A few years ago, before I started flying, I was on an American flight
out of Houston with a pretty good crosswind ripping across the runway.
I was seated near the back of the plane. A couple of seconds after
takeoff we heard a VERY loud bang, the left wing dipped momentarily,
and we continued on...

About 20 minutes later the captain came on and explained they had a
compression stall due to, he said, to the wind blowing across the
engine. He apologized for waiting so long to explain it, but he said
he and the crew were busy going through the manual for the restart
procedure.

Not being a pilot at the time, I remember thinking that maybe he should
have read the manual BEFORE flying the plane :-)




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Marco:

Don't know if it's true or not -- just what the pilot said...

Cheers,
Wiz


Marco Leon (at) wrote:
If it's really true that the crosswind caused the compression stall, I
wonder why we don't hear about a double stall very often. Theoretically, the
wind can be strong enough to affect both engines, no?

Marco Leon (at) wrote:
If it's really true that the crosswind caused the compression stall, I
wonder why we don't hear about a double stall very often. Theoretically, the
wind can be strong enough to affect both engines, no?


A gusty crosswind is probably the most common cause of compressor
stalls on commercial flights. Of course, that doesn't mean that
anytime there's a crosswind that turbofans will be belching fire left
and right. It's not that common. You have to get just the right
level of disruption in the airflow. With any given crosswind, the
airflow to each engine is going to be different, because of where they
are situated, so it's unlikely that you'd get conditions conducive to
simultaneous compressor stalls.

John Galban=====N4BQ (PA28-180)

What makes me think it was true was the fact that you continued to your
destination. If it was a malfunction, then it would be hard to justify
continuing (unless of course you're British Airways an have four
engines...). A double compression stall on takeoff would be the absolute
worst time for that to happen.

I had a roomate a while back that was a flight attendant on the Pan Am 747
that lost an engine (as in "fell off" the wing) on takeoff. Still landed
without further incident. And yes, she was quite attractive

Marco Leon

"Wiz" wrote in message
ups.com...
Marco:

Don't know if it's true or not -- just what the pilot said...

Cheers,
Wiz


Marco Leon (at) wrote:
If it's really true that the crosswind caused the compression stall, I
wonder why we don't hear about a double stall very often. Theoretically,
the
wind can be strong enough to affect both engines, no?





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"Marco Leon" mmleon(at)yahoo.com wrote in message

If it's really true that the crosswind caused the compression stall, I
wonder why we don't hear about a double stall very often. Theoretically,
the
wind can be strong enough to affect both engines, no?

Because each engine is in a different place, perhaps masked from crosswind
by the fuselage, etc. Compressor stalls due to crosswind most often occur,
in my experience, at the start of the takeoff run, if you bring the power up
too quickly and one of the engines has a disrupted flow it will pop. Once
you've got speed crosswind compressor stalls are not too common. Another
place you're vulnerable with fans is top of descent. In the 747, if we were
at or over about 370 at start of descent it was real easy to stall them.
We'd have to bring the power back easy and not all the way. Once below 350
you can bring them back to idle.