LMML 14/32 From Malta, joined Jan 2001, 2560 posts, RR: 7 Posted (8 years 9 months 3 weeks 5 days 16 hours ago) and read 2200 times:
Recently I heard that one of our B733's aborted a take-off because one of the engines flamed out during the run. The story goes that inspection revealed nothing wrong and it was put down to a gust of wind!
Starlionblue From Hong Kong, joined Feb 2004, 15904 posts, RR: 66 Reply 1, posted (8 years 9 months 3 weeks 5 days 13 hours ago) and read 2088 times:
If you get sudden crosswind at low speeds to such a degree that airflow into the engine is severely disrupted this is possible. No air into the engine results in oxygen starved combustion.
"There are no stupid questions, but there are a lot of inquisitive idiots." - from Citadel by John Ringo
Starlionblue From Hong Kong, joined Feb 2004, 15904 posts, RR: 66 Reply 3, posted (8 years 9 months 3 weeks 5 days 12 hours ago) and read 2073 times:
Sorry, yes. No air, no combustion. I assume that some air is present, but so little that the ratio of air to fuel becomes too low, and the flames go out.
"There are no stupid questions, but there are a lot of inquisitive idiots." - from Citadel by John Ringo
Greasespot From Canada, joined Apr 2004, 3054 posts, RR: 22 Reply 4, posted (8 years 9 months 3 weeks 5 days 11 hours ago) and read 2045 times:
I am gonna have to go with a dissenting opinion here and say it is not possible. Yes wind can cause a compressor stall but it will not cause a flame out. One thing about a engine is it is really good about drawing air in.
Plus on your A/C it was on the T/O run so there engine was at high power therefore drawing in enough air. You would also need so much wind it would damage the A/C by moving it around.
If that was ever to happen you would also be changing the engine as the air volume decreased you would have EGT's shoot sky high and you would over temp the engine.
I will not say it is impossible because nothing is impossible but from a engine shop perspective I would say nope that was not the problem.
Greasespot
Sometimes all you can do is look them in the eye and ask " how much did your mom drink when she was pregnant with you?"
Starlionblue From Hong Kong, joined Feb 2004, 15904 posts, RR: 66 Reply 5, posted (8 years 9 months 3 weeks 5 days 11 hours ago) and read 2037 times:
Maybe the explanation given to LMML 14/32 was unclear. They may have meant stall or surge instead of flameout. Still, if the ignitors are off air starvation could stop combustion no? At least in theory.
Air2gxs From , joined Dec 1969, posts, RR: Reply 7, posted (8 years 9 months 3 weeks 5 days 10 hours ago) and read 2016 times:
You know, I was looking at this thread and wondered about it and decided that the engine probably did not flame-out from air-starvation. As greasespot put it: jet engines are really good about drawing in air.
I'm not sure what the fuel management system is like on a 737-300, but could fuel starvation have been the problem?
We had a DC8 (same base engine) flame out because the flight crew failed to properly configure the fuel system prior to take-off. Fairly easy to do on an 8, don't know about a -300.
We wound up changing that engine because of the thermal shock of going from TO to not running without cool down. He was well into the take-off roll when it flamed-out. Was also rather cold out as I remember.
SlamClick From United States of America, joined Nov 2003, 10062 posts, RR: 71 Reply 8, posted (8 years 9 months 3 weeks 5 days 10 hours ago) and read 1993 times:
If this was possible it would be standard practice to select ignition to continuous during turbulence. Oh, that's right! We do!
Yes some kind of abormal airflow across the intakes might cause a momentary disruption of air supply through the compressors that would allow the flame to die - momentarily. That is actually called an "unstart" but it is pretty rare in routine ops. The igniters should have been on for takeoff and it should have relit almost without being noticed.
Rare? I'd say so. I've never had it happen. No one of my friends has had it happen that I know of. But the people who devise our procedures and write our manuals say it can.
After all that, I doubt that it was the real and complete explanation for this event.
Happiness is not seeing another trite Ste. Maarten photo all week long.
Starlionblue From Hong Kong, joined Feb 2004, 15904 posts, RR: 66 Reply 9, posted (8 years 9 months 3 weeks 5 days 9 hours ago) and read 1983 times:
If this was possible it would be standard practice to select ignition to continuous during turbulence. Oh, that's right! We do!
LOL Slamclick.
BTW in an arena not entirely unrelated to this one, military aviation, engines can and do "unstart" due to strange attitudes. You may have seen the Su-27/35/37 or the MiG-29 do the "Cobra", a very high angle of attack maneuver. Most military jets (and commercial jets assuming they could perform the maneuver, which they can't) would find their engines being starved at this point, and stopping, since the airflow over the intakes is essentially perpendicular to the direction of the intake (across instead of into) and at a later stage the plane is going slightly backwards.
"There are no stupid questions, but there are a lot of inquisitive idiots." - from Citadel by John Ringo
TripleDelta From Croatia, joined Jul 2004, 1053 posts, RR: 7 Reply 11, posted (8 years 9 months 3 weeks 5 days 9 hours ago) and read 1970 times:
AIRLINERS.NET CREW PHOTO SCREENER
Unstarts were quite a problem for the Olympus engines used on the Concorde, before the Rolls-Royce found a way to shutdown and restart the engines in flight. As I remember from watching Wings Over The World, this was due to the high-speed of the air entering the engine (above M0.3-0.5). An unstart usually, when it occurs, shuts down the engine due to the shock wave it produces and can even blow off a couple of engine parts.
However, I haven't heard of any unstarts on sub-sonic jets. This may be a bit naive, but can it be possible that instead of being starved of oxygen, the engine was "oversaturated" with it? Say, a sudden gust of wind hits the intake and from the shock and sudden speed change, an unstart, or a similar disruption of airflow, occurs. Or maybe even a shock to the fuel system as well. But then again, what would happen in turbulence in that case?
Air2gxs From , joined Dec 1969, posts, RR: Reply 12, posted (8 years 9 months 3 weeks 5 days 6 hours ago) and read 1909 times:
A sudden gust of wind wouldn't not lean the mixture out enough to flame-out. The air going down the core is basically controlled by the variable stator vanes (VSV's), which are wide open at TO power, and the variable bleed valves (VBV's), which are closed at TO power. Tubo-fan engines take a lot more air into the inlet than they can use. Most of that air goes into the by-pass duct. The air that goes down the core is regulated by the VSV/VBV system. A huge slug of air may cause a slight disturbance at the intake but certainly would not cause a flame-out. Remember, there is all kinds of air going down the inlet in-flight (low altitudes). Much more than on the ground.
LMML 14/32 From Malta, joined Jan 2001, 2560 posts, RR: 7 Reply 13, posted (8 years 9 months 3 weeks 5 days 4 hours ago) and read 1879 times:
Wow !!
Thanks for the mature and sensible discussion. Someone mentioned Concorde and I have a question about this too: Why the delay in lighting the #4 burner during the takeoff roll? If I am not mistaken this is also due to an airflow issue. Can someone please elaborate?
QantasA332 From Australia, joined Dec 2003, 1500 posts, RR: 35 Reply 14, posted (8 years 9 months 3 weeks 5 days 3 hours ago) and read 1890 times:
I don't think that there's a delay in lighting Concorde's #4 engine afterburner on takeoff (it is weaker initially, though), but #4 is certainly a 'limited' engine in another way. Wingtip vortices around the right wing rotate in the opposite direction to the engine's/fan's rotation, which can cause all sorts of vibration and problems at low speeds (namely takeoff). As a result, #4 is limited to 88% N1 at speeds below 60 kts. Read more here, at the very bottom of the page.
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