Turbine Engine Oil Consumption

etherealsky · Tue Oct 26, 2010 10:35 pm

I know that turbine engines boast very low oil consumption compared to reciprocating engines, but what kind of numbers are we talking about? What is the typical oil consumption for something like a CFM56, or a GE-90 (or any other turbofan for that matter) and how is it measured - qts per hour? How about GE's Gen-X; does it improve oil consumption further than current designs?

I've also heard that some operators fly so frequently that they don't need to perform oil changes because they're adding oil so often, but doesn't that contradict the assumption that turbine engines burn very little oil per hour of engine operation?

Viscount724 · Wed Oct 27, 2010 12:11 am

I've noticed maintenance staff checking the oil on various widebody types after international flights and in some cases they didn't have to add any oil. In other cases sometimes only one quart.

KELPkid · Wed Oct 27, 2010 12:44 am

Quoting etherealsky (Thread starter):
I've also heard that some operators fly so frequently that they don't need to perform oil changes because they're adding oil so often, but doesn't that contradict the assumption that turbine engines burn very little oil per hour of engine operation?

Do turbine engines even get oil changes? As I lineboy, I was always told that turbine engines eventually burn off all the oil, because the lubrication system is open loop (i.e. oil in the engine bearings is not returned to the sump, but gets burned in the engine). We only added oil to turbine powerplants when it was requested by the flight crew, though...

tdscanuck · Wed Oct 27, 2010 2:01 am

Quoting etherealsky (Thread starter):
What is the typical oil consumption for something like a CFM56, or a GE-90 (or any other turbofan for that matter) and how is it measured - qts per hour?

If you're up into the quarts per hour something's wrong...it should be well below a quart an hour.

Quoting etherealsky (Thread starter):
I've also heard that some operators fly so frequently that they don't need to perform oil changes because they're adding oil so often, but doesn't that contradict the assumption that turbine engines burn very little oil per hour of engine operation?

A lot of engine maintenance is sensitive to both calendar time and engine time...it's possible that operators with high utilization are burning oil (engine time) fast enough that their oil never gets too old (calendar time).

Quoting KELPkid (Reply 2):
turbine engines even get oil changes? As I lineboy, I was always told that turbine engines eventually burn off all the oil, because the lubrication system is open loop (i.e. oil in the engine bearings is not returned to the sump, but gets burned in the engine).

Modern engines aren't open loop...the oil gets scavenged back to the tank. There is always a breather somewhere to separate air from oil and invariably some oil mist goes out the vent, but most of it just keeps going round and round.

Tom.

jetmech · Wed Oct 27, 2010 3:02 am

Quoting etherealsky (Thread starter):
CFM56

The CFM's on A-340's almost always required 2 or 3 quarts of oil each at the end of a 7-8 hour flight, sometimes even four quarts. The RB-211's on 747's usually took 1 to 2 quarts. Trent 500's and 700's often did not require any uplift. CF6's usually took a quart.

Quoting etherealsky (Thread starter):
don't need to perform oil changes because they're adding oil so often

I don't think I've every seen an oil change on a commercial turbofan. One of the reasons you need to change the oil on reciprocating engines such as your car, is due to the fact that the oil gradually gets contaminated with combustion by-products. On commercial turbofans, the oil does not come in contact with combustion by-products, so it maintains it's physical and chemical properties for much longer.

Quoting KELPkid (Reply 2):

Most commercial turbofans use a dry-sump oil system.

http://www.globalsecurity.org/milita...ry/policy/army/fm/1-506/Fig5-1.gif

http://www.tpub.com/content/aviation/14014/img/14014_140_1.jpg

Regards, JetMech

[Edited 2010-10-26 20:04:35]

tdscanuck · Wed Oct 27, 2010 4:16 am

Quoting jetmech (Reply 4):
I don't think I've every seen an oil change on a commercial turbofan.

I've seen it, but only for engine preservation if one's coming off wing and will be stored for while (aka "pickling").

Tom.

fr8mech · Wed Oct 27, 2010 5:30 am

Our PW4000 engines have a .5qt/hour limit.
Our CF6 engines are limited to .55qt/hour. We start looking for a problem at .25qt/hour.
Our PW2000 engines are limited to .6qt/hour.
Our RB211 engines are limited to 2.2pints/hour.

To contrast, our JT9 engines were limited to 1qt/hour, but if you had no external leak, we could fly the aircraft so long as we could anticipate there was going to be 4 gallons left in the tank at destination. Our engines had 7 or so gallon tanks depending on position.

b78710 · Wed Oct 27, 2010 9:47 am

CFM's on our 340's use the most, never less than 2 quarts, sometimes up to 3 or 4 over a 7-10 hour flight.

CF6's on our jumbo's usually take a can, sometimes 2.

Trent 500's take a can if your lucky. Very often none.

In fact I believe when we first got our trents the oil consumtion was so low that we actually had some issues with the oil breaking down because it wasn't getting any fresh oil.

Quoting KELPkid (Reply 2):
Do turbine engines even get oil changes? As I lineboy, I was always told that turbine engines eventually burn off all the oil, because the lubrication system is open loop (i.e. oil in the engine bearings is not returned to the sump, but gets burned in the engine).

don't find many total loss oil systems anymore. oil is scavenged back to the gearbox, air is removed from the oil through an aerator and vented through a breather, which often runs through the shaft and out the arse end.

though on the trents, if youve ever seen smoke out the drain mast underneath the engine, this is the breather. you can just make out the faint 'smoking' in this picture, just aft of the mast. but if you ever see one taxi onto stand its quite prominent

View Large View Medium
Click here for bigger photo!

Photo © Spencer Wilmot

maddogjt8d · Wed Oct 27, 2010 2:41 pm

Just for a reference point, I have seen a similar smoke/mist from the breather on the IAE V2500 on the A320. When sitting on the port (left) side of the aircraft, you can see a similar vent device that comes off the top-right section of the middle engine cowling.

MrChips · Wed Oct 27, 2010 8:30 pm

Quoting fr8mech (Reply 6):
To contrast, our JT9 engines were limited to 1qt/hour, but if you had no external leak, we could fly the aircraft so long as we could anticipate there was going to be 4 gallons left in the tank at destination. Our engines had 7 or so gallon tanks depending on position.

Ahh, Pratt & Whitney engines, you check the fuel and fill the oil! Even their small engines go through oil like it's going out of style. The PT6s that pull me around each have 3 gallon oil tanks, of which about a quart is guaranteed to go out the exhaust (unlikely) or all over the cowling (most definitely) after a full day of flying.

[Edited 2010-10-27 13:31:29]

fr8mech · Wed Oct 27, 2010 10:08 pm

Quoting MrChips (Reply 9):
Ahh, Pratt & Whitney engines, you check the fuel and fill the oil! Even their small engines go through oil like it's going out of style.

Hey, you never saw any corrosion on them, did you?

tb727 · Wed Oct 27, 2010 11:43 pm

Quoting fr8mech (Reply 10):

Hey, you never saw any corrosion on them, did you?

Yeah, if there is no oil on the outside of a JT8D, it's outta oil. I think we are at a .5qt/hr limit.

B727LVR · Thu Oct 28, 2010 1:04 am

Quoting etherealsky (Thread starter):
What is the typical oil consumption for something like a CFM56, or a GE-90 (or any other turbofan for that matter) and how is it measured - qts per hour?

Quoting KELPkid (Reply 2):
Do turbine engines even get oil changes?

The RR Spey Mk 511-8 on the GIII aircraft has a 28L tank, and normal oil loss is .9L per/hr. It has no oil change interval, per the manual "oil change is accomplished by attrition." Kind of crazy when you think about it, but it is an extremely reliable engine!!!

crjfixer · Thu Oct 28, 2010 9:08 pm

The limit on a cf-34 3b1 (crj-200) is 6.4 oz per hour

larshjort · Thu Oct 28, 2010 9:32 pm

I don't know how much oil the operators add to thier engines on the PC-12's but we selodm have to add any at the maintenace inspections.

How do you open the cans? Which tool do you use. I use the Can Key
http://www.thecankey.com/

/Lars

KELPkid · Thu Oct 28, 2010 10:00 pm

Quoting Larshjort (Reply 14):
How do you open the cans? Which tool do you use. I use the Can Key
http://www.thecankey.com/

/Lars

Automotive oil used to be sold in metal cans in the USA, too. As a result, almost everybody (here) had a pour spout in their garage that simultaneously punctures the can, and there is a sharp dimple on the spout end you could use to make a smaller hole opposite where you inserted the spout so that the oil poured out smoothly rather than coming out in "glops." Our FBO had several of these on board the Jet-A truck, in the same compartment where cans of turbine oil were stored...

What to do with used oil cans in the USA? Target practice, of course

jetmech · Fri Oct 29, 2010 5:09 am

Quoting Larshjort (Reply 14):
How do you open the cans? Which tool do you use. I use the Can Key

I use a flat blade screwdriver

. My Snap-On flat blade screwdriver was perfect for the job, until I lost it

.

Regards, JetMech

brons2 · Fri Oct 29, 2010 5:09 am

Why in the world do they still put the turbine oil in cans? What's wrong with plastic bottles ala most OTC automotive oils?

Or, just dispense it from a tank?

Tristarsteve · Fri Oct 29, 2010 8:22 am

Quoting brons2 (Reply 17):
Or, just dispense it from a tank?

When I started on the line in 1971, I was at LHR on the BEA Trident fleet. Every engine needed oil on every transit. We had an oil lorry. It met every arrival and had an air pump that pumped the oil out. I remember it made a duff duff noise as it pumped and five duffs was a litre, so you just had to count the duffs!

Now i work on an outstation. We have not used any oil at all this month. (Except a can I put in a starter motor that was being changed)

MD11Engineer · Fri Oct 29, 2010 3:27 pm

Quoting brons2 (Reply 17):
Why in the world do they still put the turbine oil in cans? What's wrong with plastic bottles ala most OTC automotive oils?

Or, just dispense it from a tank?

Contamination issues. You use as much oil as you need from a can and then dispose of the rest. You´ll NEVER use any leftover oil on another aircraft.
This is why many aviation authorities frown upon using oil from e.g. a drum. In the few cases where I have seen such a use it was most likely in a hangar and there were strict additional procedures to prevent the oil from being contaminated.

BTW, PW4000 engines use practically no oil. I once did a flying spanner job on a 747 with PW 4000 engines over three days all over Europe and Central to East Asia and didn´t have to top up even one engine.

Jan

Mender · Fri Oct 29, 2010 4:40 pm

The oil consumption rate of a turbine engine is usually affected by changes in engine speed so an aircraft flying a 9 hour long haul sector can use less oil than when it's doing two 1 hour flights.

I once supported an aircraft that was being used for touch & go crew training from a remote airfield. A two hour flight to the remote airfield and the engines needed 1 can of oil, two hours of touch & go flying it needed six cans!

b78710 · Fri Oct 29, 2010 6:35 pm

Quoting Larshjort (Reply 14):

How do you open the cans? Which tool do you use. I use the Can Key

leatherman

RaginMav · Fri Oct 29, 2010 9:07 pm

Quoting jetmech (Reply 16):
My Snap-On flat blade screwdriver was perfect for the job, until I lost it

Lost the screwdriver, or lost the job? I'm hoping the former.

Quoting Larshjort (Reply 14):
I don't know how much oil the operators add to thier engines on the PC-12's but we selodm have to add any at the maintenace inspections.

In my brief stint in a PC-12it was one quart every 4 hours in my plane. I also flew a King Air 200 for a while, each engine burned about the same.

Quoting MrChips (Reply 9):
The PT6s that pull me around each have 3 gallon oil tanks, of which about a quart is guaranteed to go out the exhaust (unlikely) or all over the cowling (most definitely) after a full day of flying.

My current bird is TPE331 powered, so I get my fair share of crap from PT6 drivers. I get my revenge watching them climb the ladder and add oil. After several years, I have yet to add a quart to a 331, unlike my time in PT6 aircraft!

[Edited 2010-10-29 14:09:07]

jetmech · Sat Oct 30, 2010 1:28 am

Quoting RaginMav (Reply 22):
Lost the screwdriver, or lost the job? I'm hoping the former.

LOL, the screwdriver, but I did lose and then subsequently regain the job as well for reasons that had nothing to do with using the screwdriver to open oil cans!

Regards, JetMech

Jabird · Wed Sep 25, 2013 8:16 pm

What about oil consumption rates on some of the upcoming new engines, like the CFM Leap engine and the PW1000G series? Will their usage rates be about the same as the current commercial fleet of engines in general or much more or less?

Tristarsteve · Fri Sep 27, 2013 11:22 am

Quoting Jabird (Reply 24):
What about oil consumption rates on some of the upcoming new engines

Well I have now worked on both engines on the B787, just transits only oil filling, no defects yet (50 transits).
The B787 with the Trent uses no oil, same as the Trent on the B777. Just one can now and then, we did outstaion transits after a 2 hr flight and the oils were always 20/20 on Eicas.
But the B787 with the GENX is much the same as any CF6. It has the oil breather down the centre of the engine, and after shurdown oil drips onto the ground behind the engine. This means that we filled oil every time. The aircraft flew for 6 hrs to get to us and I filled 2 or 3 cans in each engine.
By the way, when you try and fill a GENX the first time, you find that the oil will not pour in. You need to dribble it in slowly. But take a plastic tye wrap, and poke it into the grill inside the oil cap, and now you can pour the oil in normally! You are opening an NRV that GE thought would open under the weight of oil as you poured it, but it doesn't.

Starlionblue · Fri Sep 27, 2013 12:20 pm

Quoting TristarSteve (Reply 25):
By the way, when you try and fill a GENX the first time, you find that the oil will not pour in. You need to dribble it in slowly. But take a plastic tye wrap, and poke it into the grill inside the oil cap, and now you can pour the oil in normally! You are opening an NRV that GE thought would open under the weight of oil as you poured it, but it doesn't.

This post makes me so happy. I am happy that despite our vaunted technical prowess as a species, we still need smart technicians with dirt under their fingernails to fix things that very qualified engineers think should just work.

n901wa · Fri Sep 27, 2013 2:34 pm

I gotta say, I agree with the Pratt oil usage, but also give them credit, the 4000 is a tight engine. If you gotta put oil in a 4000 something is going wrong, a garlock seal or nose bleed. The worst use to be the RB-211-22B on the L-1011, you would bring a case, and some guys use to wear a rain jacket to service nbr 2 eng. We use to joke that you never had to change a RB211-22B oil, because it was a total loss oil system. Send it to HNL from LAX twice, and you replaced the whole tank

The 524 was a Much better eng.
It was funny on the 27, you could tell who did the walkaround from the spots on their shirts, Flight Crew and Mechanics. Is it just me or did used 2380 smelled real bad.
As for Plastic bottles, I would bet it would eat thru it over time. Some of the Overflow plastic bottles used for servicing IDGs and Starters start out tuff, but tend to get soft after a little while.
Glad I'm not the only one that Have a Large Flat Blade Snap-on Can Opener

LH707330 · Fri Sep 27, 2013 7:29 pm

There was an old joke somewhere about a blind mechanic trying to figure out which engine was hung from a 747 wing. If you hit your head on it, it's so heavy that it must an RB211, if it drips a bit of oil on you it's a PW4056, and if it doesn't drip anything it's a CF-6 because it's burned up all of its oil already.

Dalmd88 · Fri Sep 27, 2013 7:34 pm

Count me in the large screwdiver camp also. Never liked to carry more tools than needed. As for the metal cans, they are also very easy to recycle. The plastic ones don't clean up enough to be recycled

LH707330 · Mon Oct 14, 2013 5:54 pm

Quoting TristarSteve (Reply 25):
But the B787 with the GENX is much the same as any CF6. It has the oil breather down the centre of the engine, and after shurdown oil drips onto the ground behind the engine. This means that we filled oil every time. The aircraft flew for 6 hrs to get to us and I filled 2 or 3 cans in each engine.

Do the GE and CFM56 engines burn more than the Trents because the breather goes down the center as opposed to out a small stub pipe at the bottom, or does something else cause that?

CALTECH · Mon Oct 14, 2013 8:22 pm

Quoting tb727 (Reply 11):
Yeah, if there is no oil on the outside of a JT8D, it's outta oil. I think we are at a .5qt/hr limit.

Back in the 727 days, our engines were not put on H.O.C. watch until they burned more than 1 quart an hour.

Quoting Larshjort (Reply 14):
How do you open the cans? Which tool do you use. I use the Can Key

That is a nice can opener.

I liked putting 3 holes on one side, and one hole on the other for a good steady flow.

Quoting fr8mech (Reply 10):
Hey, you never saw any corrosion on them, did you?

So very true. Pratts are like Harley's, they like to mark their parking spots.

tb727 · Mon Oct 14, 2013 9:17 pm

Quoting CALTECH (Reply 31):
Back in the 727 days, our engines were not put on H.O.C. watch until they burned more than 1 quart an hour.

That sounds about right for what we do too nowadays.

Speaking of JT8D's, those cowls are a mother to close by yourself on top of a ladder, I saw one of our mechs using something that looked a lot like this thing but I can't seem to find them to buy.

http://www.aircraftmechanic.org/showthread.php?1536-JT8-Cowl-Tool

Has anyone ever seen them before? The one in the picture above seems to be home-made.

fr8mech · Tue Oct 15, 2013 2:55 am

Quoting tb727 (Reply 32):
Has anyone ever seen them before? The one in the picture above seems to be home-made.

We used to make them. The ones we made used a strap. Gave you a lttle more leverage.

Had one similar made for B747-100/200 cowls.

DarkSnowyNight · Tue Oct 15, 2013 12:07 pm

Quoting jetmech (Reply 16):

I use a flat blade screwdriver . My Snap-On flat blade screwdriver was perfect for the job, until I lost it .

I like that. I also like using a needle nose pliers. Good easy punch thru, and we have the benefit of "opening up " that joke without having to make more smaller ones.

This is good for times when you have something like an RR powered A380 that not only needs a lot of oil, but gives a good amount of space to work with.

Quoting CALTECH (Reply 31):

I liked putting 3 holes on one side, and one hole on the other for a good steady flow.

I always tried to keep the numbers equal. But sometimes when using a flat blade, I'd just merge the holes to make one larger one. Seemed to get a good controllable flow that way too.

Quoting tb727 (Reply 32):

Anyone else notice our Indian friend there?

tb727 · Tue Oct 15, 2013 1:57 pm

Quoting darksnowynight (Reply 34):
Anyone else notice our Indian friend there?

Haha, oh yeah, look at that, didn't even see him!

n901wa · Tue Oct 15, 2013 5:03 pm

Ah, I went thru My Rollaway and found my JT8D eng cowl tool. I wonder If it would work on a MD-90? Also found my other 2 can openers I use to use. I got the cowl tool from my Pops, and the Oil servicing tools from my Grandpa. Worked great on opening cans, and dumped oil quick.

CALTECH · Sat Oct 26, 2013 2:40 pm

Quoting tb727 (Reply 32):
Speaking of JT8D's, those cowls are a mother to close by yourself on top of a ladder, I saw one of our mechs using something that looked a lot like this thing but I can't seem to find them to buy.

Remember when the 727 JT8D's lower cowls on # 1 and # 3 just didn't seem to want to close, rather than forcing it, would just get the horizontal latches closed that allowed the cowl to swing open in the other direction, then swing open and close the lower cowl in the other direction and close up those stubborn latches. Seemed to relieve the bind or whatever kept those lower cowls from closing as those stubborn latches now closed easily MOST times.

Quoting darksnowynight (Reply 34):
I always tried to keep the numbers equal. But sometimes when using a flat blade, I'd just merge the holes to make one larger one. Seemed to get a good controllable flow that way too.

Yup, would make the 3 holes one big hole.

Quoting n901wa (Reply 36):
found my JT8D eng cowl tool

Remember that tool from LAX and some outstations where really old timers worked.

LH707330 · Wed Sep 14, 2016 4:34 am

I just saw a mechanic adding oil to a 764 the other week, and that reminded me of this thread. Does anybody know exactly why the CFM56-5C burns so much more than other engines despite being smaller?

rcair1 · Wed Sep 14, 2016 3:18 pm

jetmech wrote:
Quoting etherealsky (Thread starter):CFM56
I don't think I've every seen an oil change on a commercial turbofan.

Hadn't the L-1011 that limped into Florida on #2 because all 3 lost oil just had an 'oil change' on all 3. If I remember correctly, they did not put new o-rings on the plugs and all 3 lost oil. They noted an issue on #2 and shut it down. Then while coming back they lost #1 and #3, and got #2 back up and running just long enough.

I'll have to go back and find the report.
-----
Nope - I was wrong. They did not put the o-rings on the master chip detectors and that is where the oil went out. It was service on the oil systems, but not oil changes.

Eastern 855.

They were headed Miami to Nassau. They lost oil pressure on #2 and shut it down. They decided to return to Miami due to worsening weather at Nassau. En route they lost, #3, then #1. They glided for a while and got #2 running again. Then successfully landed on #2.

Once on the ground, #2 would not produce enough thrust to taxi and they had to be towed in.

Whew!

DougS · Sat Sep 17, 2016 9:06 am

IAE V2500 burns 0.3Qt an hour. Most of that seems to get vented about 5 mins after shutdown......

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