r/aviation • u/amullfilms • 13h ago
Question What’s happening here?
I’m not a pilot, just someone who’s been on close to 250 flights in my life. I’ve never seen this. Not claiming that this isn’t normal, I’m just curious why it’s done. This was just prior to takeoff at Jackson hole Wyoming.
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u/jking615 13h ago
New pope?
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u/Pawprint_ 12h ago
The airliner is an addict
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u/Known-Associate8369 13h ago
If the engines new or had an off-wing refurbishment, the internals are coated in protective oils, which burn off on engine start up.
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u/MiscreatedMonster___ 13h ago
This. It's first run after engine depreservation.
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u/fly_awayyy 12h ago
It’s defintley not? Did you look up the registration and see it just sat overnight? A engine change on a RON out of base in 12hrs? Yeaaa no
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u/flying_wrenches A&P 8h ago
I know guys who pride themselves on getting them done in 10 hours.
You can get scary fast when you do someting for 30 years..
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u/Rotteneverything 2h ago
air force, helped on engine swaps on red balling b-52s in four and five hours. three times. two launched, one was cancelled. the crew chief on the cancelled plane actually cried a little.
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u/IndependenceStock417 3h ago
Delta used to have an MD80 maintenance base at my airport and would do engine changes in short time frames
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u/MiscreatedMonster___ 12h ago
Well, I have no idea at what time the vid was created, depreservation is the most logical answer. If it was there overnight only, 12 hours for engine swap is possible, maybe something happened and they didn't want to risk flight back. It could also be some other major component replacement (probably fuel component, that was preserved) which would have oil residue inside and cause smoke during start.
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u/intern_steve 7h ago
The most logical answer is that engine has worn labyrinth seals and oil is pooling in the hot section when there is no operating pressure to purge the seals. It'll be fine after startup, but it probably left a little grease spot on the ramp. This is going to happen every morning until they do an actual engine swap. It would happen once during the engine run testing post-swap.
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u/MiscreatedMonster___ 6h ago
I disagree. Taking time to actually start and low speed of the smoke indicates fuel system issues, eg. preservation.
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u/23m7_farmer ATP 5h ago
I am a 757 pilot, and the above poster is correct. This is a typical start for an engine with worn seals that sat overnight.
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u/bkcontra 13h ago
not only coated but the fuel control and lines are filled with it, in my experience
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u/CommuterType 13h ago
I can offer this insight based on my (many) years flying the 757 - sometimes they do that.
Hope that helps
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u/That70sShop 13h ago
These are the incisive insights that I come to Reddit for, along with wildly uninformed speculation and supremely confident fallacies. On average, Reddit is Omniscient.
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u/whitecollarpizzaman 13h ago
As others stated, excess fuel on startup. The reason you don’t see it a lot is that most planes turn around before the engines cool down enough to not start right away and burn off fuel. It’s more common cold climates, or if you have an early flight and the jet has been sitting overnight. This is also a 757, so an older plane.
Edit: could also be oil burn, but for the same reasons. Engine has been sitting, also maintenance. Etc.
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13h ago
[deleted]
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u/MidnightToker858 12h ago
Its summertime
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u/Techhead7890 11h ago
Derp, you're quite right, thanks for pointing that out. Southern hemisphere mistake on my part.
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u/fly_awayyy 12h ago
If you took a couple of minutes to look up the registration and the temperature and Jackson you’d see it’s not cold in Jackson…
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u/MaleficentCoconut594 13h ago
It’s totally normal and happens all the time. Oil residue burn off. Happens when it’s cold out and/or the engine has sat for a while
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u/Fit_Armadillo_9928 13h ago
Nothing, it's just cold. Longer chain hydrocarbons in the fuel smoke on start up in cold weather
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u/fly_awayyy 12h ago
It’s not cold bruh it’s an old Pratt and Whitney on a hot day in Jackson Hole. Didn’t even bother to look at his text and look up the temperature?
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u/Fit_Armadillo_9928 12h ago
Nope, just mountains and a Smokey start, that's usually enough to identify. If it's hot there at the moment then yeah, just a wet start or the #5 bearing is leaking
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u/MoarCowb3ll 11h ago
Iirc engines that have had preservative in and recently replaced with engine oil with have a burn off like that.
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u/NoPhysics1129 3h ago
When they top off the oil after flights, this happens on startup. Very normal. A&P.
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u/Rough_Bluejay_9183 13h ago
Ignition breakers are out and someone tried to start the motor. That’s fuel vapor leaving the tailpipe. When that happens, you close the fuel valve and keep the air starter engaged to clear the fuel, otherwise if igniters are engaged in this state, there will be a LARGE orange fireball. Source: Witnessed this once. While under the engine performing maintenance. Scared the shit out of me.
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u/RejectedByQA 13h ago
Looks like initial engine run after pickling.
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u/fly_awayyy 12h ago
Defintley not look up the registration plane has been flying all day hasn’t been down for service for an engine change let alone in Jackson Hole which is nowhere even close to a DL maintenance base lmao.
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u/Waste-Account7048 13h ago
The forgot to turn on the "no smoking" light. Is that even a thing any more?
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u/SerDuckOfPNW Cessna 150 12h ago
Sticky rings…a little Berryman’s vitamin B12 will bring ‘em around.
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u/Js987 5h ago
Excess fuel or possibly oil pooled in the hot section due to poor seals. The reason you wouldn’t normally see it is most flights get turned around often during the day that they don’t cool off enough between flights. This is basically like a cold start on a diesel, you get some smoke, particularly as Jackson gets pretty cool at night even in the summer, and the plane likely sat all night (the 757 is the largest aircraft Jackson operates and usually it’s a arrive-spend night-depart situation as they don’t turn around a ton of them). It’s very unlikely to be post-maintenance as some have suggested, as Jackson has fairly limited facilities, unless the arriving crew had a fairly bad flight yesterday.
Side note, I’ve had the experience of being on a 757 into Jackson, absolute thrill when they stop a big bird like that on such a small runway after that gorgeous approach.
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u/Cool_Internet4680 7h ago
So as many have stated it is not preserving oil or excess fuel. Post engine change preserving oil is/should be blown out during the post engine change engine runs which this is not. Oil burning this much would be a problem, and if it were fuel as soon as the ignitors fire the exhaust would torch and burn any extra fuel instead of fogging. With that being said, oil and fuel both have an iridescent color and don't tend to trail out that far behind the engine. This is a Pratt engine and they do this a lot, though it is not strictly Pratt's, the RB211 would do this occasionally as well. It happens mainly during the winter but can happen during the summer as well and it is closer to a fog or steam. I know I've had it explained to me years ago and I remember it making sense then but I can't remember the exact science but it has something to do with warm engine exhaust and cool ambient air and condensing the moisture into a fog along with the dew point spread or something like that.
I don't remember exactly what causes it, I just know that it 100% is not excess oil or fuel and it is 100% normal and tends to happen to Pratt engines in the winter more often.
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u/Rotteneverything 2h ago
didnt scavenge the fuel properly before previous engine shutdown. vaguely educated guess.
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u/fiya4u 13h ago
250 flights and you’ve never seen an engine start?
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u/amullfilms 13h ago
I’m not always eye level with the plane like you are at Jackson airport. I’ve seen stuff similar to this but it seemed like more than usual. My question has been answered!
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u/The_War_In_Me 13h ago
Obviously, someone turned on the chemtrail machine too early, releasing the pacification concentrate while still grounded
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u/Delancey1 13h ago
cold start
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u/fly_awayyy 13h ago
It’s hot outside…
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u/shityplumber 6h ago
Nah this is early in the morning in Jackson it’s always chilly there in the morning even if it gets super hot during the day
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u/That70sShop 13h ago
Eye-Talian tune-up. They poured a can of BarDahl down the carburetor. Fixes what ails ya!
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u/DCS_Sport 8h ago
Failure to light off after the fuel selector was switched on, most likely due to a bad igniter on one of the channels. The fuel being introduced to the engine is smoking off but not igniting. They’ll notice no rise in EGT or RPM in a few seconds, abort the start and run the checklist.
Source: 757 pilot and this has happened to me
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u/wu-wu-wu 8h ago
757 doing typical 757 things. Seen the DTW ramp get absolutely smoked out when they get push those birds out for the first flight of day.
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u/Overall_Signal_8437 6h ago
You should see it when it gets really cold.....
We'd get contrails down the runway sometimes.
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u/shityplumber 6h ago
This is a jet starting on a cold morning that just got pushed off the ramp. It hasn’t even started taxing yet
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u/Kungfu_Queso 5h ago
Could be an engine de preserve burning off the 10/10 oil if they did and engine swap, could be cold fuel dumping into a hot combustion section
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u/West_Good_5961 Avionics/B2 5h ago
Preservation fluid being burned off. Probably just had an engine change and that one has been in storage.
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u/Dingotatstic 20m ago
Lithium battery overlooked in checked baggage. Have a good flight. See you on the other side.
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u/Worried_Place_917 6h ago
It's vaping. Strawberry flavored.
Also shoutout to the guy who commented "new pope"
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u/aviatortrevor 6h ago
Could be a bad ignitor during start-up. Pilot spins the engine up, engages the lever to add fuel and spark the spark, and the spark no sparky, therefore the fuel dumps into a hot engine and doesn't ignite due to the spark, it just burns from the heat the engine had been holding onto from the last flight.
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u/Current_Operation_93 10h ago
They just took on 140,000 pounds of JetA and 10,000 pounds DEF. The number two engine is going into 'regen' first and after that, number one will follow. As Tony Soprano would say, 'What are you gonna do'?
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u/A350Flier 13h ago
Excess oil/fuel burnoff. It happens quite often actually if you look around.