Engine Start-Is that smoke from fuel or oil

[JammedStab]

https://www.youtube.com/watch?v=8DfTX-IAkdg

L-1011

[Exup]

Smoke, probably just had an engine change & it looks like the first start burning off inhibiting fluid.

[Mozella]

I never did bid the 1011, but my airline operated many of them and I liked riding on them. This much smoke on start up was certainly not normal, but it happened from time to time at low temperatures. I don't believe it is necessarily associated with an engine change.

Since I wasn't checked out on the 1011, I don't know what else contributed to this huge amount of smoke, perhaps a cross bleed start or a weak start cart. I do remember making a PA announcement or two to calm my passengers when they saw an event like the one in the video.

[JammedStab]

The reason I ask is because we had a difficult start on an Allison engine once with lots of white smoke becoming visible to us. The FE stated that we were looking at "raw fuel".

[nitpicker330]

Happens a lot to all Jets in really cold weather after a cold soak.

Watch them startup on a really cold day.

The seals probably don't seal fully until they warm up a bit?



Edit----just watched the video and that's a lot of smoke, the cold Aircraft I mention above don't emit that much!!

[TOWTEAMBASE]

That took a heck of a long while to wind up, maybe premature fuel ??. And why were they filming it, I'd say they were expecting it to have issues, maybe it's been sat idle for a while !

[MrSnuggles]

White smoke usually means "clean" smoke, water vapours, carbon dioxide, etc. Black smoke indicates high carbon content and/or only partially combusted fuel/oil.

That said, I have no idea why this much smoke appeared. Wild guess would be a long still standing engine blowing out some condensed water vapour. Wild guess, mind you.

[SMOC]

Smoke by definition occurs as a result of combustion, while I agree it can be inhibiting fluid involved in the video it would be interesting to know the temperature of the day, I've done wet spins on very cold mornings with cold engines where upon selecting fuel on the fuel vapour appears to condense and appear visually. Later doing the normal start the condition can be seen to stop immediately at the time when combustion begins, luckily it was a BA 747 with RB211-524D4s which as many know make a distinctive noise at light-off, therefore confirming the point of combustion coinciding with the vapour cloud stoping.

Unfortunately every video or picture of cases like these refers to it as smoke giving the impression it's like burning oil which is incorrect, it can still be seen today during very cold mornings where there is a short burst of fuel vapour/condensation but light-off occurs some time after as expected on a cold morning, usually after the aircraft has been parked overnight allowing the entire engine to get cold soaked.

http://www.airliners.net/photo/Northwest-Airlines/Airbus-A319-114/0473034/L/

[ampclamp]

Looks like a hell of a wet start with that white mist. But surely they would not have let it go that long if so? Spun up for quite while and did not light off for a while after it cleared by the sound of it.

[Stanwell]

ampclamp,
You got it - that's kero (avtur).
A definition: "Smoke is the visible sign of incomplete combustion".
Seen it before but it didn't take as long as that, though.

[grounded27]

I would agree that is most likely pickling fluid/ fluid fuel mix, I noticed a partial light. The reason I say this is I have been on the headset of an aircraft inside a blast fence, it was starting to surround me and I came very close to bailing out. It could have just been fuel, it is common to see with an ignition system failure (switch systems and you get a light). Also if the aircraft had been sitting a long time the FF may be erratic so they may have elected for it to stabilize before a light. On a normal start in cold weather many PW engines put off lots of vapor.

[lomapaseo]

I assume that the spin-spark and spray is being followed and this stuff doesn't burn. I also assume that the light off inside the engine occurs just at the time that we pick up the low frequency hum. Always amazed that the flame front doesn't jump backwards out the tailpipe.

I have seen this on the L1011's at the gate several times on a cold winter morning

[bcgallacher]

RB 211-22B engines were prone to this at low ambient air temps - saw this many times.It was usually accompanied by slow acceleration to idle or a hung start with low egt. Never saw it on Tristar or 747 with any of the -524 series engines - the VIGV and FCU systems were different. A newly installed engine will also do this while burning off inhibiting fluid in the fuel system.

[DevX]

I would say that the engine has either been overhauled or in storage (or both) as that's definitely inhibiting fluid. The long length of time taken to light is indicative of an unprimed engine so a manual wet crank, followed by a minimum of 30 secs. drying out crank should have been carried out prior to trying for a real start. This would have purged the inhibiting fluid and primed the engine thus ensuring a normal start.

[BOAC73]

Spot on DevX,
And if you had an engine change away from base it was wise to inform the tower and the fire station what was likely to happen. A wet cycle never seemed to fully purge in my experience.

[Feather #3]

However, when we start an R-3350, it's ALL of the above!!:ooh:

G'day ;)

[Tinwacker]

Smoke, probably just had an engine change & it looks like the first start burning off inhibiting fluid.

Spot on after an engine change, and as another writer mentions I would have advised the tower that a smokey engine would be starting, and not to sent the fire trucks.

This is not a normal engine start prior to aircraft pushback.

Note the heavy wheel chocks still in place, the undercarriage doors are still open, flaps partially lowered and maintenance steps still close to the fuselage.. post engine change first run-up.

[Mozella]

I can't say if you're right or wrong because I have no information about this particular aircraft. It may very well have been following an engine change.

However, I can say with certainty that the L-1011's my airline flew (I'm retired now) rather frequently smoked like this at the gate on cold days not associated with any engine change. I've witnessed this many times and the amount of smoke is astounding.

As I said earlier, I was never checked out on the 1011 so I can't say for sure what causes this much smoke and it may not be quite accurate to call it "normal" because it didn't happen on every cold weather start, but it happened often enough that it was not considered abnormal or worrisome (except perhaps to the passengers).

[Goldenrivett]

Hi Mozella,

Here's another link showing lots of smoke from a TriStar's RB211's engine.
https://www.youtube.com/watch?v=F8dezbfQC4I

"Because of a very weak APU, numerous engine starts were attempted and most resulted in "hung" starts, except for this one. After this engine (number 1) was started, they were then able to crossbleed to the other 2 engines which were then able to start normally. This start was almost a hung start as well, creating extra smoke, but then the engine does start to pick up RPM and is able to complete its start cycle. Any L10 lover will enjoy seeing this sight and hearing the sounds once again....Enjoy!!!"

If the APU was weak, the engine would not accelerate properly and to help it accelerate an "Enrich" setting was selectable. It was permissable to "blip" the Enrich on and off during engine start, between certain N3 RPMs. This introduced more fuel than normally scheduled and produced clouds of un- burned fuel. If Enrich was still on when N3 was above 35%, then to avoid starter motor damage, it had to remain on until start valve closed. If the APU was particularly weak, then this could mean a long time with Enrich on whilst the engine accelerated slowly. I suspect that is the reason for the smoke in the first video.

http://www.blackholes.org.uk/PP/RB211%20start.jpg

[601]

What is the duty cycle time for the starter on this engine?

[JammedStab]

Cold weather does seem to have an effect sometimes as seen on this A320.

https://www.youtube.com/watch?v=Neq8AOgcOVk

[Goldenrivett]

Hi 601

What is the duty cycle time for the starter on this engine?
"STARTER LIMITATIONS
Normal Cycle
Up to 3 minutes continuous operation then run down to zero N3.
Up to a further 3 minutes continuous operation then run down to zero N3.
Up to a further 1 minute continuous operation then run down to zero N3 and allow to
cool for 30 minutes.
Extended Cycle
5 minutes maximum continuous operation, and then run down to zero N3 and let the starter cool for 30 minutes."

[barit1]

Newly delivered 747 on the ramp, I was booked to ride jump seat to collect data. A crew of airline techhies transitioning to 747 were crowded in the cockpit, so I was relaxed in the upper lounge awaiting the flight time.

I heard a groaning sound - maybe hydrailics? - What were those fixerguys doing to this airplane?

I looked outside and - AHA! - A TriStar 1 km. down the ramp was emitting a large cloud of white vapor from #2. Loooonnng groaning continued a minute or more. Finally the smoke and the noise ceased almost simultaneously. Then the wing engines began the same complaint cycle. :E

Weather was clear, OAT near ISA.

[JRBarrett]

Reading the full description of the YouTube video, it was an L1011 belonging to an aviation museum, and they were doing engine runs in preparation for flying the aircraft to a new location.

It would explain why the start was being filmed, the maintenance stands, multiple chocks etc. Probably the first start after a very long idle period, and with inhibiter fluid still in the system.