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TOPIC: Cracked Oil Sump

Cracked Oil Sump 1 month 2 weeks ago #1662

Thank you for this update, Ken. Very interesting.
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Cracked Oil Sump 1 month 2 weeks ago #1659

  • KENT VANDENBERG
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Hello All,

My ordeal with the cracked oil sump is finally winding down. Here's a synopsis and pictures.

The engine was removed by an A&P mechanic and shipped via ground transportation to Western Skyways as a warranty return.

I personally witnessed the opening of the engine at the Western Skyways factory in Montrose, CO on Monday, September 23. The diagnosis by Western was a metallurgy failure of the pan. There was no evidence of anything coming apart internal to the engine and no strike marks were found on the inside of the pan in the area of the crack. The oil filter was removed, opened, and inspected for metal with none found. No metal inside the pan, and no metal found when probing around in the engine case.

The explanation I was given by the factory is as follows:

The oil pan configured with the Continental IO-470-S engine in the 1964 Cessna 205A is the same oil pan as configured with the same engine in the 1964 Cessna 210. This is because the 1964 Cessna 205A is certified under the same type certificate as the 1964 Cessna 210. The Cessna 205A model number reflects this, model 210-5A. In many respects, the 1964 Cessna 205A is the same as the 1964 Cessna 210 except for fixed gear.

The oil pan has a concave, oval shaped formed area in the bottom of the pan which is needed to provide clearance for the retractable nose gear of the Cessna 210. The formed area, all things being equal, can form a stress riser or weak area in the pan if there is a manufacturing or metal defect. That the crack initiated on the radius of the formed area supports this postulation. There is sufficient clearance in the airframe of the Cessna 205A such that an oil pan with the formed area is not required (no retractable nose gear). The Continental IO-470-S engine is allowed to be fitted with a "straight pan", ie, one without the formed area. The repair was to fit an approved oil pan with does not have the formed area, thus eliminating a source of cracking.

I have enclosed pictures of the oil pan exterior and a closeup, and the oil pan interior and a closeup; note the oval shaped formed area. Also included are pictures of the engine interior in the area of the oil pan crack, and the new "straight" oil pan fitted to the engine.

The engine was test run for two hours at Western Skyways per their normal acceptance procedure and all parameters passed. They said they would open the oil filter and inspect for metal after the test run but I was not there is witness that operation so I assume it was done and checked okay. The engine will be arriving back to the home base airport this week and thence installed.










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Cracked Oil Sump 2 months 3 weeks ago #1563

I remember a crack in a 182 was posted in a different Cessna forum several years ago. It was determined that all started before installing the engine, in transportation or handling. The crack was not obvious until it was worsened by the normal vibration of the engine.
Last Edit: 2 months 3 weeks ago by JOSE LOPEZ DEL PUERTO.
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Cracked Oil Sump 2 months 3 weeks ago #1544

  • STEVE ELLS
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Hey Kent;
This photo shows the crack. Very unusual. I don't believe I've ever seen that. Since you're under warranty with Western Skyways, I expect you to have zero cost out of pocket.
Check the oil filter first, if it's clean I don't see the need to pull the prop governor, but I would propose that to Western Skyways just to make absolutely sure that there has been no engine damage.
It is possible (I believe) to change oil sumps without pulling the engine. Check with Western Skyways and your mechanic.
Thanks for sending in this story.
Very unusual.
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Cracked Oil Sump 2 months 3 weeks ago #1543

  • KENT VANDENBERG
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Thank you Steve and Jen. The failure looks like at crack but the engine is still in the airframe. Will get removing that in a week or so. A&P is very overbooked. My initial thought was it was the oil quick drain but that's not the case. Great suggestion to check the governor screen, will do that, in addition to already planning on opening the oil filter to look for metal. The overhaul has 6 months left on a 3 year warranty so it will be sent to Western Skyways in Montrose, CO, and I plan to go there when it gets opened to see what's going on inside. I'll try to upload a picture of the crack in the oil pan.
Kent.


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Cracked Oil Sump 2 months 4 weeks ago #1541

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Some of the early Continental engines has oil sumps cast of magnesium, if I remember correctly. And there have been reports of those sumps corroding through.
The sumps on the IO and O-470 series are stamped steel so aren't prey to the type of corrosion that attacks the magnesium cases.
Are you sure that the oil quick drain valve didn't leak|?
If you want to know if your engine has been contaminated by metal, pull the prop governor and look at the screen that's part of the governor gasket.
You'll also want to pull the oil filter and cut it apart to see if it contains any metal.
And, if your mechanic has a borescope, he can inspect the inside of the oil pan (after the oil is drained) for metal.
If you still had 4 quarts of oil remaining and the OP and OT were in the green, I doubt that any oil-related damage occurred.
I will query engine builders to see if IO and O 470 sump failures are anything they've seen.
Please take pictures of the failure, and include the pictures with a description of what you find.
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