Metal oil line into turbo on T337C

[rmorris]

I have a question regarding a metal oil lin running into my T337C. I just bought this plane about 5 weeks ago. Have had to make a "urgen" landing on a single engine twice already.

In both cases the oil pressure on the rear disappeared, and then I shut down the rear engine and made my way to the nearest reasonable airport. Pulling up to the line the rear portion of the plane was draped in oil.

In both cases it was the little metal oil line running into the turbo had broken in two pieces right near where it goes into the metal plate bolted to the turbo.

The first time I landed at a field where they specialize in Aerostar's with turbos. They identified the line quickly and then pulled it off. They said that they normally replace that type of line on an Aerostar with a threaded fitting tapped into the metal plate and then a flex line threaded onto it (eliminate the rigid metal piece entirely). They debated this move, but it qas going to require a bunch of research to see if it could be done on a Skymaster. Their other idea was to take the tube to a welding shop and have the line repaired...that is the option that was pursued. They put it back on and said it would last as long as if it was new.

Approx 7hrs (hobbs time) later, I had that same line break in flight.

My homefield a&p (who is just now learning the Skymaster) is going to research it today.

I told him that I either want the line replaced, or that cool "Aerostar" modification made to eliminate the rigid metal line.

Anyh one know a place to buy that line (and a part number) or anythign about a mod to keep that line from ruining my future flights?

-robert
rmorris@agsi.us
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Mazda F Platform Picture

[Paul Sharp]

What ever ended up happening with your oil line problem? I can't imagine this being anywhere normal or we'd be seeing it cropping up regularly and this is the first time I ever remember hearing about this as a problem. Seems to me that something else would be causing this. I have a T337B and have never had any problem with that sort of thing, and never read about anyone else having it happen. Twice in a row is really suspicious.

[rmorris]

From the a&p/IA talking with other Skymaster owners, it looks like the weld job that "repaired" the line the first time - was not heat treated.

I tried to order a replacement fitting from someone on Monday via the mechanic, but they failed to ship it out overnight as requested. We then went to plan B.

I called ATC (Approved Turbo Components) in Florida [based on a recommendation I received]. Mike looked it up and said there was a direct replacment fitting that would solve the issue. I ordered it and it is now sitting on the airplane, but not yet tightened down. Also, if you go this route, you will need a different and expensive check valve for it based on threading.
Seems that with the new fitting (which is MUCH larger and thicker than the original), there are two issues:
1) The angle and length of the new fitting, along with the new check valve, cause it to go right into the side of the engine. This can be worked around by using a righght angle fitting into the end of the check valve and now you go go under to the flex line as before
2) The size and angle of the new larger pipe make it virtually impossible to get to the backside bolt to tighten it down. The mechanic worked on it for several hours Wednesday before finally throwing in the towel. I am awaiting his thoughts on how to resolve (ie make a tool, buy some funky angled tool, sell the plane, etc. If anyone has thoughts on it, please let me know. Can you easily remove the front chamber on the turbo and separate the two halves, thus making it easy to get an angle on that back bolt of the oil line fitting?
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RENT GUARANTEE ADVICE

[Kim Geyer]

You should be able to loosen the bolts that hold the compressor half and the exhaust half and rotate them out of the way. your mech. is most likely going to have to remove the turbo to do this. once he has torqued and saftied the oil fitting bolt he can move the halves back to where they were or reindex them to a position that provides the best clearence for all the lines. You should also check for any damage to the impellers as a slight imbalance of the rotor will break those lines and the mounts. Also make sure the line and the oil hose aren't so close to anything that they could hit while the engine is running.
hope this helps
Kim