Jet turbine engine oils

[JHZR2]

Ill have to see what we use at work.. I work at NAVSEA Philadelphia, and we have a HUGE land based engineeering site, that has a trainer LM2500 and a new 38MW Rolls engine, that is the prime powerplant for the DD(X)/DDG1000... THey have barrels of turbine oil around, I think they fill them with a Mobil product, but I have to look for sure...

JMH

 

[Terry]

But please answer this question. In the unloaded turbine engine, say a typical huge jet engine, the amount of fuel going through it being thousands of gallons on a coast to coast flight (or further), how does the oil serving the bearings on each side of the hot section keep from getting
any combustion particles in it?"



Labyrinth seals, a hydrodynamic lube "wedge" forming the support for the seals around the bearings. If the seal leaks or the fluid breaks down the blowby can be catastrophic and cause engine failure.

The turbine engine oil SHOULD never see combustion byproduct in normal conditions.

 

[Cujet]

Hi Tom,

I wonder if you can shed some light of carbon or coking issues with the 23699 oils. We use BP-2380 (of course) because it is available everywhere, even Russia. However the Trouble-Mecca engines in our heli's are having some carbon formation due to heat. Can you suggest a better oil?

Also, ZF, the heli trans MFG, has come out with a non mandatory SB (service bulletin) for use of some special trans oil (non 23699). Can you shed some light on what may be different?

Chris

 

[Tom NJ]

Hi Chris,

The MIL-PRF-23699 specification has three grades defined: STD (Standard), C/I (Corrosion Inhibited), and HTS (High Thermal Stability). The HTS grade is designed specifically to reduce deposits caused by high temperatures. The military does buy and stock some HTS grade, or if you are using commercial oils the common HTS types are BP 2197, AeroShell 560, Royco 560, and EM 254. Since other factors may be involved, you should use only oils approved by the manufacturer, which should include some HTS grades.

Regarding the ZF service bulletin, what type or specification do they recommend? If it is the DoD oil (Mil-PRF-85734) then this is the same as 23699 STD except it has higher load carrying capability.

Tom

 

[Cujet]

I have been unable to find a spec for the super ZF trans oil. To comply with the SB, they require a 30L purchase (3x what fills the trans). I assume that it is not common.

Thank you for the input on the HTS types. I kinda knew the info, in a round about way, as certain oils are known to work better. But I was unaware of the HTS grading.

Chris

 

[MolaKule]

Oil Pan 4,

It may be those advanced (AlkyPhenol-type) Anti-oxidants that break you outt but you must extremely sensitive to have this contact dermatitus.

 

[MolaKule]

http://www.howstuffworks.com/framed.htm?...edu537/turbine/

http://www.howstuffworks.com/framed.htm?...Engines101.html

Each shaft turns on two or more bearings, called "bearing cells" in which pressurized oil is fed to the cells and then carried back to the reservoir. Each bearing cell has special spring-loaded carbon seals. Heat from the combuster, turbine disk(s) and heat from the compressor are conducted to the bearing cells. The hot oil is first cooled by the fuel then an air-to-oil heat exchanger. The oil is filtered twice before being sent to the bearing cells.

There may be one, two, or three shafts in the engine, depending on engine type, thrust and application.

 

[kd5byb]

This is a great thread!

I work at an Army jet engine test facility, where we run Army T700-GE-701C's, 701D's, Navy 401C's, Army T55-L/GA-712/714's, and an Army GTCP36-155 APU out of the Apache. (I ran the -155 today, in fact.) We stock 23699 by the 55 gallon drum.

My comments!

HTS. The Army does seem to have type HTS in the system. We prefer not to use HTS and have taken a liking to Mobil Jet Oil II.

The OCI question is interesting - most of the engines we've tested burn enough oil that changing oil is sort of silly proposition. I seem to recall that a T700 will use a quart about every 20 to 25 hours and be in limits for consumption, and with a 7 or 8 quart sump (I forget), you're on fresh oil pretty quickly. We did a long test for NAVAIR on a 401C where they did ask for an oil change and analysis at some point. Not sure what they found in the analysis, we just changed the oil and pulled the sample.

Hot end seals - on the T700, and I assume the T55, most of the seals are pressurized with bleed air, so even if the seals leak, you're leaking from the high pressure side (oil sump) to the hot side. You don't get flow the other way. I've never seen oil in a turboshaft change color from contamination. This makes sense - if you keep out the contamination products from combustion, the oil will stay pretty darn clean.

There is an urban legend that notes that the T700 oil filter is so fine that the oil in the can is dirtier than whats in the engine after one pass.

thanks much,
ben

 

[kd5byb]

Quote:

---

However the Trouble-Mecca engines in our heli's are having some carbon formation due to heat. Can you suggest a better oil?

---

Hey Chris - which Turbomeca engines are y'all having problems with?

Looking at 23699, the HTS flavor is supposed to help prevent coking, as HTS = High Thermal Stability. If you can run HTS, I'd suggest trying that. What does Turbomeca say?

Be careful going to HTS - I've heard stories of HTS cleaning off coking left by STD/CI flavor 23699's, causing filter bypass problems, etc...

later,
b

 

[jerrylee]

Are we talking about Redline......

 

[Cujet]

Our flight department operates a Gulfstream G550 equipped with 2 BMW-RR BR510 engines and a Honeywell R-eally E-xpensive-220 APU, A Pilatapus PC-12/45 with the Pratt PT-6, A Eurocopter EC-135 equipped with 2 Trouble-Mecca Arrius 2B1_A1 engines and a troublesome ZF main rotor transmission. We also have 2 Extra EA-300L aerobatic planes and a couple of DG gliders.

We only have 2 pilots and 1 mechanic (me) so the flight time per aircraft is quite low.

We had one of the Turbomecca's let go (in flight) in a very remote area of the carribean. It had about 280 hours total time on it. That was exciting. We landed on a tiny Island with 1 house on it. They told us to leave. Not without a new engine!

We brought the loaner eng to a 1700 foot coral runway in the Pilatus. That in itself was really fun.

You should have seen the Turbomecca rep watching us put his loaner engine on the 13 foot Boston Whaler and take it 20 miles to the (Gilligans) Island. It was not a smooth day, and it was a long ride. Good thing it was wrapped up in plastic.

Chris

 

[kd5byb]

Heh heh heh! Sounds like a lot of fun. I had a flight test Chinook blow out a hyd line, but it was over the airfield so no big deal.

We're not fond of HoneyAlliedWell ourselves either! They seem to be a lot harder to deal with than say, General Electric. We really like GE. I can email them a tough question and get an email back in 15 minutes. Not so with Honeywell. I do have to admit that the 714A is a workhorse...

Although Honeywell ground services (the people who sell Honeywell's specialty tooling) are on the ball and great to deal with! We recently bought a bunch of APU overhaul tooling from them...

later,
b