What Is This Smoke Coming Out Of The Engine? — Tech Ops Forum

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What Is This Smoke Coming Out Of The Engine?

BA From United States of America, joined May 2000, 11135 posts, RR: 61
Posted (9 years 2 months 1 week 6 days 21 hours ago) and read 4363 times:

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Look right underneath the Rolls-Royce Trent 772B. What is that small puff of smoke or steam coming out the bottom? I have never seen this before.

Any feedback would be greatly appreciated.

Regards

"Generosity is giving more than you can, and pride is taking less than you need." - Khalil Gibran

13 replies: All unread, jump to last

Q330 From Australia, joined Dec 2003, 1460 posts, RR: 24
Reply 1, posted (9 years 2 months 1 week 6 days 21 hours ago) and read 4312 times:

Looks like tire smoke to me. I don't think it's coming from the engine.

-Q

Long live the A330!

Q330 From Australia, joined Dec 2003, 1460 posts, RR: 24
Reply 2, posted (9 years 2 months 1 week 6 days 21 hours ago) and read 4252 times:

Oh, wait, it might not be on the runway! Nuts

If it's not, I have no idea what it is.

-Q

[Edited 2004-03-10 03:20:52]

Long live the A330!

AJ From Australia, joined Nov 1999, 2376 posts, RR: 27
Reply 3, posted (9 years 2 months 1 week 6 days 21 hours ago) and read 4217 times:

Most likely steam from the oil breather.

Srbmod From United States of America, joined Mar 2001, 16888 posts, RR: 51
Reply 4, posted (9 years 2 months 1 week 6 days 21 hours ago) and read 4218 times:

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A Rolls-Rolls engine that smokes? Wow!

What a novel concept.

OPNLguy From , joined Dec 1969, posts, RR:
Reply 5, posted (9 years 2 months 1 week 6 days 21 hours ago) and read 4167 times:

Ah, yes, the glorious days of airline steam... Big grin

(Probably an oil breather....)

LHcapt2007 From United States of America, joined Mar 2004, 235 posts, RR: 0
Reply 6, posted (9 years 2 months 1 week 6 days 21 hours ago) and read 4114 times:

Any possibility of the shifting hydraulic loads imposed from slats/flaps/landing gear contributing to the smoke? Steam from the oil breather sounds ligit, but was this pic on landing or TO(I know the reversers arent deployed but maybe just at touchdown or rollout if a landing, prob TO)?

LHcapt2007

[Edited 2004-03-10 03:32:27]

TNCM

BA From United States of America, joined May 2000, 11135 posts, RR: 61
Reply 7, posted (9 years 2 months 1 week 6 days 21 hours ago) and read 4048 times:

Thanks for the feedback everyone!

LHcapt2007,

It's on a taxiway, it could have either landed and gotten of the runway and is taxiing now or it could be taxiing to the runway for take-off. It certainly can't be taking off on the taxiway. Smile

Regards

"Generosity is giving more than you can, and pride is taking less than you need." - Khalil Gibran

LHcapt2007 From United States of America, joined Mar 2004, 235 posts, RR: 0
Reply 8, posted (9 years 2 months 1 week 6 days 21 hours ago) and read 4016 times:

LOL shouldve looked at the BIG TAXIWAY LINE right under the nose gear... duh thanks!

cheers

TNCM

BR715-A1-30 From , joined Dec 1969, posts, RR:
Reply 9, posted (9 years 2 months 1 week 6 days 20 hours ago) and read 3895 times:

That is the smoke from the Oil Breather Vent. A Common sight on BR715s too.

Q330 From Australia, joined Dec 2003, 1460 posts, RR: 24
Reply 10, posted (9 years 2 months 1 week 6 days 20 hours ago) and read 3823 times:

LOL shouldve looked at the BIG TAXIWAY LINE right under the nose gear... duh thanks!

I should have noticed that too, before I made that first post. Of course, taxiway lines do start on the runway and then curve off where there is a runway exit, but the plane is probably on a taxiway.

-Q

Long live the A330!

Broke From United States of America, joined Apr 2002, 1322 posts, RR: 4
Reply 11, posted (9 years 2 months 1 week 6 days 11 hours ago) and read 3636 times:

On all jet engines there is some leakage of high pressure air past the seals at the bearings into the oil system. This usually occurs at the bearings that are in the high pressure compressor/high pressure turbine assembly. The oil breather allows this air to dump overboard and not pressurize the oil system. The air is vented through a fixed devise that centrifuges the oil out of the air so, usually, there is little or no loss of oil out of the breather.
What I believe you are looking at is the air coming out of the breather. The air is warm and in humid or cold areas you may see condensation forming in the exhaust. If the engine losing oil out of the breather, the color of the breather air will be darker and there is generally staining on the cowling at the exhaust port.

VC-10 From United Kingdom, joined Oct 1999, 3677 posts, RR: 37
Reply 12, posted (9 years 2 months 1 week 6 days 11 hours ago) and read 3629 times:

On all jet engines there is some leakage of high pressure air past the seals at the bearings into the oil system

That's what keeps the oil in! The rotor bearings are in a sump which is basically a box with the rotor shaft passing through it. Oil jets spray oil on the bearings in the sump and higher pressure air is fed into another 'box' around the sump. This air leaks into the sump through the seals and so keep the oil in the sump.

Both the oil and the air is extracted from the sump through the scavenge oil pumps and the mixture eventually finds its way to the oil tank in which there is a de-airator. Once separated from the oil the air is vented to the gearbox and vents to atmosphere via the centrifugal oil breather that removes any remaining oil from the air. It is this oil/air vapour you see in the picture.

You generally see the vapour when an engine is accelerating or decelerating as the internal pressures are unbalanced at this time.