Smoking airbus?
 

I was watching A/C on the apron and noticed some very wierd happenings with one particular A330 on start up. There was a substantial plume of blue smoke eminating from one of the engines, now this was not black smoke that one may normally notice during climb out etc.
My suspicions lie, as the smoke was very blue in colour, with unspent fuel mixture lying in the combustion chamber (can this happen?), but as I never noticed this before (with non piston A/C) I felt I sould ask the question, what did I see?
This only occured in one of the engines and may have lasted only a second.

VF
P.S. I am happy the smoke was not drifting from somewhere else....

Hmm.....not sure about that one. Firstly, are you sure of the exact type. I know that some airbus family use the IAE V2500 series of engne. This type normally dry cranks for about 30 seconds prior to ingnition, in order to enable the fan blades to settle into the keyways, and to blow unburnt fuel from inside the cowling. The CFM series does not do this, and start is initiated from cold so to speak. I think perhaps a Powerplant mechanic may have a better idea.....

Tailwinds

Guys, I often see A330 start up in front of the crew room. They almost systematically spew blue smoke from their engines on startup... Don't know why.

well, something is burning there, perhaps oil?

We operate PW4168A engines on our A330 and this happens quite often, especially with cold engines. As far as I know, it's oil that is burned. Same thing with the PW engines on our MD-11.

Yes, burning oil is a possibility.....The CFM 56 will burn about .5 quarts/hour, and the V2500 series, about .3 quarts an hour.

Tailwinds

Correct me if I´m wrong. This is a very normal thing to see, especially with cold engines (larger turbofans eng. such as the RB211 (older ones) PW4000, and on some JT9D) It is allso seen during shut down. On some engines it is fuel (from the nozzels or other areas) that is purged into the turbine to make a "controled" cooling/warm up during startup/shutdown. It can allso be oil from pressure bearings, where the internal pressure keep the oil on the "oil" side of the bearing, and when the engine is spooled up the oil press is greater that the press that keep the oil "inside" so to speak. And during spool down, the internal press is decreasing, and since oil press is greater some oil is let into the engine hot section and come out as smoke.

On other engines this allso happens, but at a much smaller scale and mostly not visible.

Is allso depends on what kind of ignitor plugs the engings have. The "glow" type will smoke more than the "spark" type, don´t ask me why, but thats what I been told.

[This message has been edited by Danish Pilot (edited 19 April 2001).]

Come on guys, if the smoke's white, then it's fuel, if it's blue then it's oil and if it's black then it is no good at all!!

Most of these engines have air pressure (that is engine air P off x stage bleed) used to seal the oil bearings. When shuting down the engine, the decay of the sealing air is quicker than the oil P, still pumping some oil "overboard". Next time you start, there comes the blue smoke...

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... cut my wings and I'll die ...

WHITE=FUEL

BLUE=OIL

I´ve seen this on the RR RB-211 quite a few times. I´ve also been told its burning oil.

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Nothing to see here, just making use of the internet!

PanicButton: Yes, some of the OLDER Rb211 smokes, but not so much the new ones. And just for the record, the oil doesn´t burn, is just vapourises in the hot section, like a BBQ in the summer.... :)

(sorry for poor spelling)