Thought I would share this interesting failure.
Some Background Details:
Our hangar neighbor had an interesting oil leak show up on his C206. Just to confirm how novel this may be, I did a quick title search of posts citing oil leaks here on Supercub.org which revealed several of the usual suspects. However, nothing like this incident, so I think this may be a new one.
This Cessna 206 has a reman IO-520, is flown weekly, with approximate total time of 1250 hours on the engine since it was installed.
The owner observed oil dripping from the cowl flaps and rear of the cowling. Checked the oil level, no significant loss. The upper cowling was removed, and it looked like a small quantity of oil coated the firewall and the rear of the engine. An initial guess was probably a leak at a hose connection to the remote oil filter or possibly somewhere on the back of the engine. After cleaning up the oil, no noticeable leak source observed, so re-installed the upper cowling.
The next day or so, the owner flew home, about 1.5 hours flight time. After landing he noticed it was still leaking, now much more than before. Lost about ¾ of a quart of oil during the flight. Now it’s serious; so, the owner and his A&P removed both cowling halves, inspected the engine and noticed a small dent on the bottom of the oil pan. Obvious thoughts are something failed inside, denting the pan.
Next step, pull the engine, remove the oil pan and see what failed. Nothing noted. Now what?
So, as they cleaned the oil pan, a small shiny/dented/hammered section was noted on the bottom of the pan. See Figures 3-5.
The owner had an idea, the dented area appeared to align with the dip stick location. Sure enough, when they lined up the pan and the dip stick, the dip stick end contacted with the pan.
By the way, the dip stick is original to the engine.
Conclusion:
So, it appears the dip stick end had been in contact with the oil pan since the reman engine was installed on his C206, 1250+ hours ago. So, whenever the engine was running, vibration caused the dip stick end to bounce around, hammering into the oil pan, until it finally, a crease formed, and the dip stick tip punctured the pan and caused the leak.
Therefore, the conclusion is, dip stick size does matter.
Figure 1 IO-520 as Removed from a C206. Note Oil Pan on Floor.
Figure 2 Oil Pan As Removed. Note Circle Lower Left, Opposite Drain, Indicating Suspect Area.
Figure 3 Closer Look at Suspect Area Inside on Oil Pan Interior.
Figure 4 Oil Pan Exterior Exhibiting Failure Site.
Figure 5 Closer View of the Failure Site from Figure 4.
Some Background Details:
Our hangar neighbor had an interesting oil leak show up on his C206. Just to confirm how novel this may be, I did a quick title search of posts citing oil leaks here on Supercub.org which revealed several of the usual suspects. However, nothing like this incident, so I think this may be a new one.
This Cessna 206 has a reman IO-520, is flown weekly, with approximate total time of 1250 hours on the engine since it was installed.
The owner observed oil dripping from the cowl flaps and rear of the cowling. Checked the oil level, no significant loss. The upper cowling was removed, and it looked like a small quantity of oil coated the firewall and the rear of the engine. An initial guess was probably a leak at a hose connection to the remote oil filter or possibly somewhere on the back of the engine. After cleaning up the oil, no noticeable leak source observed, so re-installed the upper cowling.
The next day or so, the owner flew home, about 1.5 hours flight time. After landing he noticed it was still leaking, now much more than before. Lost about ¾ of a quart of oil during the flight. Now it’s serious; so, the owner and his A&P removed both cowling halves, inspected the engine and noticed a small dent on the bottom of the oil pan. Obvious thoughts are something failed inside, denting the pan.
Next step, pull the engine, remove the oil pan and see what failed. Nothing noted. Now what?
So, as they cleaned the oil pan, a small shiny/dented/hammered section was noted on the bottom of the pan. See Figures 3-5.
The owner had an idea, the dented area appeared to align with the dip stick location. Sure enough, when they lined up the pan and the dip stick, the dip stick end contacted with the pan.
By the way, the dip stick is original to the engine.
Conclusion:
So, it appears the dip stick end had been in contact with the oil pan since the reman engine was installed on his C206, 1250+ hours ago. So, whenever the engine was running, vibration caused the dip stick end to bounce around, hammering into the oil pan, until it finally, a crease formed, and the dip stick tip punctured the pan and caused the leak.
Therefore, the conclusion is, dip stick size does matter.
Figure 1 IO-520 as Removed from a C206. Note Oil Pan on Floor.
Figure 2 Oil Pan As Removed. Note Circle Lower Left, Opposite Drain, Indicating Suspect Area.
Figure 3 Closer Look at Suspect Area Inside on Oil Pan Interior.
Figure 4 Oil Pan Exterior Exhibiting Failure Site.
Figure 5 Closer View of the Failure Site from Figure 4.
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