Christen inverted oil system

[dhmoose]

I recently purchased an RV-8 with a Christen inverted oil system. Problem is, the original owner has not gone inverted in ~16 years leading me to worry that the balls and seats within the oil valve and oil separator are corroded or filled with sludge. I understand that the ball in the separator is not removable or accessible but the ball in the oil valve is maintainable.

My question is, should I…
1) Assume that the system is beyond cleaning/repair (based on the decades since last inverted flight) and order a new separator and valve right off the bat?
2) Plan to order some o-rings and maybe a new ball for the oil valve in the hopes of cleaning it and keeping it in service and replace the separator?
3) Plan to order some o-rings and maybe a new ball for the oil valve in the hopes of cleaning it and keeping it in service and plan to clean the separator?

Thanks!

 

[[email protected]]

I would start by tearing apart anything I could and clean it up. hoses and all. If they are the supplied hoses they probably need replacing. Mine came with automotive heater type hoses.
One needs to understand the system before a problem occurs. I'm sure somebody will post a schematic of the system. Pretty simple.
My luck varies Fixit

 

[dhmoose]

I would start by tearing apart anything I could and clean it up. hoses and all. If they are the supplied hoses they probably need replacing. Mine came with automotive heater type hoses.
One needs to understand the system before a problem occurs. I'm sure somebody will post a schematic of the system. Pretty simple.
My luck varies Fixit

Good advice. I have the original manual and have studied the schematic of the system. What I am unsure of is the likelihood that the system can be cleaned or if 16 years of non-use (of the inverted portions) equates to replacement instead it cleaning. Looks like the original owner installed the “deluxe” aeroquip hose kit with high quality stainless braided lines. Not sure on the lifespan of those although I seem to recall them being lifetime hoses.

 

[eaglen92ce]

If you have trouble getting the separator cleaned up and working I have a good one I would like to sell. I just removed it from my RV6 and the ball is free and working properly.

 

[1flyingyogi]

It's not that hard to remove, clean, and test to see if it's working properly. There's a procedure for testing it. If you can't find it, PM me and I can help. I just did it for my Raven system a few months ago. It does take time, but not technically difficult.

 

[rmarshall234]

I would just order the orings and assume it needs a good cleaning. When you get the oil valve apart you will know if there is any corrosion in there requiring parts replacement but my guess would be no. The separator can be cleaned by filling it with mineral spirits and soak, drain, repeat as necessary. It’s a pretty simple, crude and robust system, it just needs attention. As Brian said, nothing difficult about it and there is good info out there. Make sure you hook the oil lines back up where they belong, done improperly, that could ruin your day.

 

[dhmoose]

Thanks

I appreciate the input guys. I’ll inspect, clean, and hope for the best and if something appears in need of replacement, so be it. Bill, I might reach out if my inspection turns up some issues. Thanks for the offer.

 

[Capflyer]

The valve can easily be taken apart. Both ends have disks that are held in with circlips. I have a Christian system that came with my engine that had not been flown in years. I opened up the valve to inspect and clean and both the inside and ball looked like new.

 

[Pilot135pd]

After reading this, I'd definitely do the same as you're doing and go over every part of that system

https://vansairforce.net/community/showthread.php?t=220051

 

[rmarshall234]

Here’s a tip…when you get the oil valve out and on the bench you’ll prolly need compressed air to get the caps off once you’ve removed the snap rings. Blow air into the fitting closest to the cap with the OV in a vice, cap facing upward. It will come out with force so cover with a rag and catch it. Cheers.

 

[JonJay]

According to Christen’s manual, “due to robust design and few moving parts service is normally not required”.

The Bucker hadn’t been upside down, negative, for many years when I bought it. I flew it upside down, negative, a lot for many more years. I never had any issues. The aircraft was restored and engine rebuilt in 2015. Logs are extensive on the rebuild but no mention of the Christen system. I’ve “aged out”’of negative G’s, just isn’t fun anymore, so it may be many years more before it goes negative again. I do only “gentleman’s” aero now.

Curious to know what folks are looking for when they take these apart and what they are finding. The report on the accident aircraft, noted above, stated oil pressure loss from a hose connected to the valve was a possibility but inconclusive. The valve itself wasn’t listed as a possible cause.

So, for those that have chosen to take them apart, what have you found that would be concerning?

 

[rmarshall234]

I’ve had a few of them apart and haven’t found anything that needed attention, just a good cleaning. The oil valve has a couple of very large ball type check valves and springs that allow it to “shuttle”. It’s this shuttle feature that is most important.

One of the local acro pilots had a problem with the shuttle feature which caused oil starvation and a subsequent engine seizure when she rolled back upright. I can’t say for certain it was a Christen system but I believe so.

To me, it’s one of those risk things that has low probability but very high consequences. Servicing is easy and provides for good peace of mind.

 

[camillodinucci]

Inverted Kit IO-390 EXP119

I'm not sure if this would be the best place for this topic.

How do I switch on the inverted flight kit on the IO390 EXP119 engine? Could someone trace the paths that the hoses should make, and also show where I should connect the nipples, and the parts?

Below I send the photos of the engine, I don't know where I should connect each nipple on the engine, I note that one of the nipples has a double connection (input or output), anyway, could someone with more knowledge provide me a connection diagram?

Below, I send the photos.

Thank you so much!

 

[RV8JD]

According to Christen’s manual, “due to robust design and few moving parts service is normally not required”.

It's interesting to note that Lycoming SI No. 1397A, "Overflow Oil from Breather Fitting of Inverted Oil System", states:

"... As a means of forestalling any problems that can arise from residue in the oil separator, it is recommended that the oil separator be removed from the aircraft and flushed with a petroleum solvent, such as mineral spirits or equivalent, every 300 hours of operation, or any time there is evidence of oil being discharged from the breather fitting."​

Note that the original version of the SI was published January 25, 1980 and contained virtually the same wording as above.


Also, the Extra 300L Service Manual states nearly the same thing:

"Cleaning Inverted Oil System

The inverted oil system must be flushed with a suitable petroleum solvent, such as varsol, every 300 (three hundred) hours of engine operation or when there is evidence of the loss of oil through the breather line after normal flight."​

 

[JonJay]

That’s good info Carl.

 

[dhmoose]

Inverted oil system oil valve

Just a follow up to my original post. I removed the oil valve from the 16 year old Christen Inverted Oil system and took it apart after ordering two o-rings from Aviat Husky in advance. Everything looked brand new inside. No corrosion or sludge was seen.

Thanks for everyone’s help.

 

[rmarshall234]

Sweet, now you have peace of mind - invaluable!