Interesting Oil Leak Anomaly

Ted

Ted

The pilot formerly known as Twin Engine Ted
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On my trip to Belize and back, the 310's left prop started leaving a fine mist around the nose bowl. The props had sat for several months during engine overhaul and they are at the 6 year mark, so it wasn't entirely unexpected that the seals start getting dry.

After returning from Belize, we cleaned it off and confirmed the leak was from the prop area. Also did an oil change and this time added CamGuard since the engines showed proper signs of being broken in and had 25 hours on them. Ok, need to take care of this at some point before too long.

On the trip up to Newfoundland (~7.5 hours on the Hobbs), no oil mist. We're flying home tomorrow (at least, that's the plan), so we're now thinking that we will monitor the prop to see if the leak returns. The year limit on props (which we don't have to adhere to as it's not an AD and we're Part 91) is 6 years, so we're right there. I had hoped to get at least another year out of the props until having to overhaul them. Since we fly regularly and they're still working well, that should be doable. Likely another year will be 100-200 hours.

I'm curious from the A&Ps if you all have seen leaks like this fix themselves. I could see the seals shrinking/hardening a bit from sitting, and then getting some fresh oil would help that. CamGuard advertises one of the benefits of conditioning the seals, so that may have helped as well.
 
Ted DuPuis said:
On my trip to Belize and back, the 310's left prop started leaving a fine mist around the nose bowl. The props had sat for several months during engine overhaul and they are at the 6 year mark, so it wasn't entirely unexpected that the seals start getting dry.

I'm curious from the A&Ps if you all have seen leaks like this fix themselves. I could see the seals shrinking/hardening a bit from sitting, and then getting some fresh oil would help that. CamGuard advertises one of the benefits of conditioning the seals, so that may have helped as well.
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Not an A&P, but the Mooney was also having some slight oil leakage from the prop when it was still sitting in the hangar in WA. Ever since I picked it up and have been flying it regularly, no further problems.

Airplanes like to fly - I think Sugar Pop missed you! :)
 
Yes, I am not surprised at all. If it stops, I wouldn't worry about it. But I think you knew that already.
 
Other thing is, if the prop blades are not in ad shape, just do an inspection and reveal. Save money and avoid losing material from the blades. Or so I have been told...
 
Temp change. Belize warm, Newfoundland not so much. My Hartzel does the same thing.

If you have a single engine you carry wind screen cleaner. ;)
 
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We figured we'd do a reseal if we did need to remove it.

We'll just monitor it and see. I'm not sure about the ambient temperatre making much difference since the engines were running at roughly the same. Probably just a sitting/not sitting deal. But if it starts leaking again in the summer, we'll reevaluate. Some of the folks on the Twin Cessna forum have claimed seeping props like that for years with no ill effects, but I'd prefer to not have oil leaks if avoidable.
 
Not unusual, in fact a deep cycle of the prop is McCaully's recommendation for correcting leaks in the field. I wouldn't sweat it
 
The MT prop on the -7A starting throwing a little oil like you mention, even though it was getting flown pretty regularly. We talked to a MT guy at Oshkosh that year and told him that even though we were right at the calendar o/h time for the prop, it only had a few hundred hours on it. He said to send it in anyway. We kept flying it for a few months (so we could wait until winter for the plane to sit idle for a while) and shortly before we removed the prop to send it off, the prop started 'sticking' at a certain RPM - wouldn't come out of coarse pitch when slowing to land, etc. After that, we decided not to wait any longer and sent the prop in. Sure enough, the seal, as well as some other internal parts, were worn and had to be replaced.

Since then, no oil on the nose and no sticky prop.
 
It seems like the McCauley and Hartzell props last better than MTs.
 
Ted - what props are you running, Hartzell or McCauley?
 
KRyan said:
Ted - what props are you running, Hartzell or McCauley?
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They're 3-bladed McCauleys, which are what the Colemill conversion has with it.

I prefer Hartzells by quite a bit and I'd like to update the props with newer variants (primarily in the interest of noise reduction, plus maybe a few knots better in cruise), but when I approached Hartzell about it I got a cold response.
 
I'm an A&P and no, I haven't experienced leaking prop seals heal themselves. Even if I had, how could one claim that it would happen again? If you want to fly around in the Bermuda Triangle with leaky prop seals that's your call but what exactly is it you think you're going to get by asking this question here? :dunno:
 
Silvaire said:
I'm an A&P and no, I haven't experienced leaking prop seals heal themselves. Even if I had, how could one claim that it would happen again? If you want to fly around in the Bermuda Triangle with leaky prop seals that's your call but what exactly is it you think you're going to get by asking this question here? :dunno:
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The same thing most who post here think they will get, an answer to a question and advice or input from someone who had a similar experience.
 
bbchien said:
Ted- dome oil, or engine oil (red vs uncolored?).
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Engine oil. Another 6 hours yesterday, still not leaking. We'll keep monitoring it.
 
Silvaire said:
I'm an A&P and no, I haven't experienced leaking prop seals heal themselves. Even if I had, how could one claim that it would happen again? If you want to fly around in the Bermuda Triangle with leaky prop seals that's your call but what exactly is it you think you're going to get by asking this question here? :dunno:
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What I got already from others - useful, productive input. :thumbsup:
 
Skylane81E said:
May not even be the prop, crankshaft seals can send oil out much the same way.
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Possibly so. When our shop looked at the initial leak they said it was the prop, but leaks like that can be hard to positively identify.
 
Skylane81E said:
May not even be the prop, crankshaft seals can send oil out much the same way.
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Yep...had that in a Piper Dakota over Lake Huron. Landed on an island (Gore Bay) and inspected. Cleaned it up and ran it up twice, no leaks. Flew back to ND without a a problem. A month later it let go completely.
 
Ted DuPuis said:
Possibly so. When our shop looked at the initial leak they said it was the prop, but leaks like that can be hard to positively identify.
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Very hard, thing is if it wasn't red it wasn't likely the prop itself leaking.

In fact given the recent overhaul perhaps the oring on the prop (it was replaced right?) got pinched, rolled, or just loaded funny at install.

If you look at the back of the prop where it meets the crank flange you can look for oil having been slung out from the seam between the hub and the flange.
 
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LDJones said:
Yep...had that in a Piper Dakota over Lake Huron. Landed on an island (Gore Bay) and inspected. Cleaned it up and ran it up twice, no leaks. Flew back to ND without a a problem. A month later it let go completely.
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Whoa! That must have made you a religious guy, when it all let go, thinking what could have been over Huron.
 
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