Turbo oil leak... Bummer.

[wombat]

I don't know exactly how long this has been going on, but I just noticed it while doing an oil change.  I'm at 35 hours since annual.   I wasn't there for the annual so I don't know if it was getting wet at all then.

• Before next flight? 
• Within the next couple of flights?
• Before next annual?
• At next annual?

I did call a local shop and they have room for me on Monday, so that's nice.

Any thoughts on what is likely the problem?

• Just loose?
• Crack?
• Pilot miscontrol?

  I'm at < 400 hours (tach) since factory re-manufacture and 35 hours since annual.

[N201MKTurbo]

I think that check valve has AN fittings on both ends. If so, the elbow isn’t the proper fitting.

[Fly Boomer]

2 hours ago, wombat said:

Any thoughts on what is likely the problem?

Did the turbo come off at the annual?

[Z W]

Hard to tell from the photos where the oil is, but I would suspect a clogged check valve or loose hose connection. If a check valve is stuck open, oil will pool in the lowest part of the system and leak out.

I would have the check valves disassembled and cleaned and put a wrench on everything and tighten it all up. Clean thoroughly, run up or fly around the pattern a couple of times, and look for more leaks. Let it sit overnight and look for more leaks again.

There are also seals between the hose fitting blocks and the turbo, I believe. I bought new ones from Aircraft Spruce for something like $15.00 chasing a similar issue. Turned out that wasn't the problem, but you could buy those cheap enough and send them to the shop with the plane just in case.

[Ragsf15e]

Id especially check whether those fittings are correct as @N201MKTurbo suggests.  Also +1 on check valve cleaning.

[Pinecone]

The other issue that can cause a oil leak is an issue with scavenge pump.  If it is not sucking out faster than the supply is pumping in, you can pressure the turbo.

Main Turbo has a test for this.  They disconnect both oil lines and stick the ends in a jar half full of oil.  Spinning the engine should cause the oil level in the jar to go down.

[wombat]

Talked to my regular A&P; he said he noticed similar oil during annual and tightened the bolts.   No other turbo work has been done since I bought it ~200 hours and 2 years ago.  I have a bit of a hard time believing it's the wrong fitting, that seems like something that wouldn't take multiple years to manifest.  Maybe?   Just seems odd to me that it would take so long.  An oil pump or check valve failing seems more likely partway though the life.

 

I'll try to do a runup tonight without the cowl and see if there is any indication of if the oil is showing up during the engine run or after.

[Ragsf15e]

1 hour ago, wombat said:

Talked to my regular A&P; he said he noticed similar oil during annual and tightened the bolts.   No other turbo work has been done since I bought it ~200 hours and 2 years ago.  I have a bit of a hard time believing it's the wrong fitting, that seems like something that wouldn't take multiple years to manifest.  Maybe?   Just seems odd to me that it would take so long.  An oil pump or check valve failing seems more likely partway though the life.

 

I'll try to do a runup tonight without the cowl and see if there is any indication of if the oil is showing up during the engine run or after.

The thing with the check valves is that they are probably original.  They aren’t required to replace and they are expensive, so they are usually just left there until they don’t work.

[kortopates]

Most of the time check valves just need cleaning out.

Often the nipple on the steel fittings get cracked from over torquing the hose. It may only need a new fitting to stop the leak if its just dripping from the hose connection. 

[wombat]

Sooo....    Got the plane back from the shop.   IFR certified up to 28,000'.  Yikes!

 

But the interesting part is that the oil is coming from the quick-drain on the sump and from the mess that I made when changing the oil.

The quick-drain is apparently supposed to have a cap over it and it didn't have one when I bought the plane, so I never thought to look in the box of spare parts for one.   

And then when I changed the oil, I accidentally spilled and it ran down the bottom of the oil line to the bottom of the turbo.

[Z W]

I've started keeping a can of brake cleaner on hand in the hangar. After the oil change, where some oil always gets somewhere, I spray the bottom of the engine compartment down pretty good with it and wipe up all the oil I can see. Then I do the run up and look for major leaks before applying mousemilk to the wastegate and exhaust joints and re-cowling.

At least this way I figure every 25 hours or so the oil and gunk gets cleaned off the bottom of the motor, making it easier in theory to spot the source of any leaks later.

Your mileage my vary... Good luck.

[Ragsf15e]

So I have irrational fears about airplane maintenance, and I even helped on this!  Can someone share a picture of how their check valves are mounted?  Did we put ours back in the correct directions after cleaning them out?  That smaller back one would stop oil to the turbo if it’s backwards!  I think we did it right?  You can see the “cap” that screws into the “barrel” on the smaller check valve.

[Z W]

[Ragsf15e]

1 hour ago, Z W said:

Excellent, thanks.  Looks like mine are exactly the same as yours.

[Pinecone]

Next time, take a picture BEFORE you take things apart.

[N201MKTurbo]

When we design a system we try to make things poka yoke. A Japanese term for mistake proofing. We try to make electrical connectors so they cannot be plugged into the wrong place, and/or if they are plugged in wrong, they don't do anything bad.

These check valves are the best example of not being poka yoke I've ever seen. You can swap the feed and return valves and you can put them in backwards.

There are 8 different ways to put these valves in, and only one is correct.

[Ragsf15e]

4 hours ago, N201MKTurbo said:

When we design a system we try to make things poka yoke. A Japanese term for mistake proofing. We try to make electrical connectors so they cannot be plugged into the wrong place, and/or if they are plugged in wrong, they don't do anything bad.

These check valves are the best example of not being poka yoke I've ever seen. You can swap the feed and return valves and you can put them in backwards.

There are 8 different ways to put these valves in, and only one is correct.

And I think at least two of those ways could leave the turbo with no oil!!

[Ragsf15e]

5 hours ago, Pinecone said:

Next time, take a picture BEFORE you take things apart.

No doubt, thanks;-)!

[N201MKTurbo]

40 minutes ago, Ragsf15e said:

And I think at least two of those ways could leave the turbo with no oil!!

Yep. And 5 ways that will pump lots of oil out of the turbo because it will block the scavenger pump.