jet leaking oil...

[svcta]

I saw a citation today at TMB that was leaking oil from #1 pretty quickly. Just sitting on the ramp(and had been for the hour after I showed up and left, so I think it had been sitting for a little while). Must have been at least a quart or two on the ground and more coming out almost continuously.

It was leaking from the drain mast on the nacelle. I don't really know much about how specifically turbines lubricate themselves. Where would this come from just sitting static?

 

[avbug]

As a general rule, turbines don't use oil. Some more than others. Leaking is another matter. The only place a turbine engine should be losing oil, and it should be very minimal, is the lab seals on shutdown. Sometimes you'll see a little smoke after shutdown; the labrynth seals are pressure seals that should work nearly perfectly during operation, but which can leak whn the engine is shut down. Any leakage is minimal, and in that case smoke is usually visible in the intake area or out the tailpipe/exhaust.

Oil coming from a gang drain or collector is generaly coming out of a garlock seal or a separator unit...or an overflow. Are you sure it was turbine oil, or could it have been fuel, or fuel mixed with other fluids?

Turbine engines must be recently run to check oil. I've known more than a few pilots to check oil on a preflight, decide based on what they see that it needs oil, and proceed to overfill the engine. The result may very well be a lot of oil draining overboard, or even potential engine damage as result. What you see could be coming from a number of sources, but pilot error often ranks right at the top of the source list.

 

[BoilerPilot]

Oil Leak

Depending on the model of Citation...

If it had a JT-15 strapped to it then they are notorious for having check valves stick not sure by the description of where you said it was coming from if that is what is was. Like avbug says to realistically check the oil on a turbine it needs to be done 10-15 mins or so after shutdown. I still check it in a preflight just out of habit, but it's the after shutdown check that's the important one. I could be off base on the leak but it is a habit of the older citations....

 

[PUNISHER]

Sometimes you'll see a little smoke after shutdown; the labrynth seals are pressure seals that should work nearly perfectly during operation, but which can leak whn the engine is shut down. Any leakage is minimal, and in that case smoke is usually visible in the intake area or out the tailpipe/exhaust.

The CF700 is notorious for this.

 

[svcta]

Citation II. Wasn't jet fuel as nearly as I could tell. The line guy got some fingers in it for a sniffer test and he said no( I had pax boarding and my own a/c to worry about so I didn't get in to it)...and the color was off for jet fuel. It was the color of 5606, but I've never flown a jet that was serviced with 5606 that I'm aware of. Isn't one of the turbine oils also a similar color? I haven't poured any in about 7 or 8 years.

 

[avbug]

Citation II. Wasn't jet fuel as nearly as I could tell. The line guy got some fingers in it for a sniffer test and he said no( I had pax boarding and my own a/c to worry about so I didn't get in to it)...and the color was off for jet fuel. It was the color of 5606, but I've never flown a jet that was serviced with 5606 that I'm aware of. Isn't one of the turbine oils also a similar color? I haven't poured any in about 7 or 8 years.

H5606 is standard hydraulic fluid for many aircraft...much more common than skydrol (and not nearly as nasty). What you saw could also have been hydraulic fluid...not necessarily oil. It could have been fuel, too. Fuel that sits on the tarmac tends to thicken and change colors. It may also have been a combination of fluids. In any event, it's something that needs to be checked out before the aircraft flies again.

 

[Groucho]

The CFM also leaks both fuel and oil. I had a mech explain it to me this way. When the aircraft is parked with a strong tail wind there is strong rotation in the fan section and often a much slower rotation in N2, the core. This has everything going backwards and the oil and fuel pumps turn backwards just a little.

The shaft seals also don't like the reverse flow and they leak. The drip rate out the mast of a CFM series can get up to sixty drops a minute, that's one a second, and still meet spec. The engine has to be run and checked after a 5 minute static run up. This almost always gets the seals to line up correctly and the pumps to scavange the sumps correctly and the engine "dries up and runs right."

When a Pratt leaks, it leaks cause something is loose somewhere.

 

[sbn340mech]

It's not leaking oil, just marking its territory

 

[wms]

If it stops leaking, then you should worry.

 

[avbug]

That would be a round piston engine.