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Crankshaft Seal Blowout In Flight and Emergency Landing

Congrats to you sir for keeping cool and flying the airplane.

I can only hope and prepare that if i were put in that situation that i could remain as composed as you did and get the plane, myself and passenger down safely.

Godspeed
 
Gash said:
Third, from a previous life, I flew a couple thousand hours in the F-16 where we practiced simulated flameout (SFO) patterns regularly.
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errr...ummm. I think that pretty much explains the successful outcome.

I've always had a habit of a high pattern altitude... even on a straight in approach. I've learned to enjoy forward slips so much that now I purposely do them.

Inspiring post to say the least Gash! Thanks!
 
DanH said:
The big thread is here:

http://www.vansairforce.com/community/showthread.php?t=92980

See posts 98, 227, and 236 for relief valve information. Use a NAPA 2-29000.
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Dan, thanks for the link and part number. That's a big help. I'm slapping myself in the forehead for not having read that thread, as it really has all the information one would need to avoid this problem. Hindsight 20/20, etc...

Acceptable risk based on knowledge is good, but risk due to lack of knowledge is unacceptable.
 
Oil Flow

Gash said:
Yes, absolutely. Here was my thinking at the time:

1. Descent. Oil was gushing out of my engine fast. It's hard describe the extreme flow volume, but it was breathtaking. My first thought was to reduce the rate the engine was pumping oil overboard by bringing the power back. Data download shows that I initially pulled the power to 17" MAP and descended at 800 FPM until I saw I could definitely make the field, then I reduced to 9" or less for the remainder of the flight. Reduce power = airplane slows down or goes down (or both).
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Unfortunately, with a constant speed prop, simply reducing power won't have any effect on oil flow. You have to reduce engine RPM to reduce oil flow, and even then you'll have to reduce it a lot because the oil pressure relief valve pretty much ensures constant flow through the engine until you get down to 1600 hundred RPM or less...maybe a little higher with hot oil...to make a significant difference.

Skylor
RV-8
 
woxofswa said:
Not too long ago I flew my first extended night flight from PVU to FFZ. It was smooth as silk, and my wife and daughter were blissfully asleep after a full day of the airplane actually being useful. It was also pitch black and I was admiring the capabilities of the SkyView system. About 20 miles or so ESE of BCE I decided to lean a little further and play around with the MPG rating. About a minute later, the engine suddenly and forcefully "burped". I immediately restored the fuel flow to where it had been and it returned to its normal sewing machine cadence. It had never done that before and hasn't ever since. I took the incident of a sign to fly smarter and always keep the envelope as large as possible. The terrain I was over was almost certainly lethal to dead stick. When my heart restarted, I tried to calculate if I would have been able to glide to Escalante, but there was no way. Off in the distance, I could see the lights of Page. My direct course would take me west of there but I turned toward Page and continued down over TBC, etc. Strong SA obviously benefited you and while it is tempting to fly as efficiently as possible, sometimes it makes more sense to take a slightly more meandering route, the execution of which demands higher situational awareness in itself.
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Myron, I'm disappointed that I missed your carne asada at Copperstate, but I'm TRULY SAD that I missed your wife's brownies! ...and raiding your cooler of course.

Thanks for sharing your experience and thoughts about route planning. I often use Foreflight to compare time/distance/fuel differences between careless direct routing and thoughtful routes that take potential forced landings into consideration. The difference is usually nothing more than 5 minutes or a half a gallon of fuel here and there. The minimal savings are not worth the risk.
 
Question...somewhat related...

If I'm not interested in the possibility of picking up a little extra power, and care more about keeping the belly of my plane clean (I'm getting old, and just want to fly!) why not route the breather to a well vented canister attached to the lower firewall?

It could then be checked every oil change and emptied, as well as determine if the gunk amount is significantly different from the last change and investigate.

I suspect I'm missing something...
 
TomRV8 said:
If I'm not interested in the possibility of picking up a little extra power, and care more about keeping the belly of my plane clean (I'm getting old, and just want to fly!) why not route the breather to a well vented canister attached to the lower firewall?

It could then be checked every oil change and emptied, as well as determine if the gunk amount is significantly different from the last change and investigate.

I suspect I'm missing something...
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Hu? my 2001 Dodge Cummins came with a crank case breather bottle....Good idea!
 
TomRV8 said:
If I'm not interested in the possibility of picking up a little extra power, and care more about keeping the belly of my plane clean (I'm getting old, and just want to fly!) why not route the breather to a well vented canister attached to the lower firewall?
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The goal is to capture the oil that's coming out due to unusual attitude operation. Straight and level flight rarely puts out enough oil through the breather to make much of a mark on the belly... If it does, you're running your oil level too high or something else might be wrong.

The separator is the first line of defense in this... It captures the majority of what might fall out the breather while inverting and returns it to the case. A second can below it would capture any overflow (which is minimized anyway by the separator), but then that capture can would overflow and dump during the same inverted manoeuvers... So by the time your oil change came around you'd be cleaning the belly just as much as before.

Maybe you could put a second separator after the first, and route it to the exhaust pipe, with redundant pressure relief valves and extra plumbing and... and...

In the end it seems like a lot of extra hassle. A separator with an overflow tube that ends just above the exhaust pipe, inside the cowling, right at the firewall, will allow any drips to spill on the outside of the exhaust, and either burn off or run off. Try to keep the G's positive and it'll be less of a problem. :)

To the original poster though, awesome work on getting it down in the circumstances. I always practice power-off approaches, just for situations like this. Now I need to go read up on high-key, low-key to see how they relate to what I do... :)
 
Did anyone in here recieve a mailing from Antisplat warning of this possibility? I know I didnt. But, thankfully....I do read far to much of these forums and knew of the danger. Still, for Alan to expect that every pilot would read these forums AND this thread which isn't titled to get the proper attention is foolish. I've said before and I'll say again, Alan is a great guy.... who will end up penniless if he doesn't stop putting out aircraft parts that aren't properly engineered and tested. Like Dynon's unforgivable delay in the freezing pitot tube fiasco....Alan shouldn't be sleeping until this is fixed or recalled.

With that said....the valve is still in mine, even though I did find more than a little build up of carbon in my saddle tube.
 
Alternative

I haven't hadmuch luck in convincing everyone to remove these deivices, in spite of my own testing and experiences, as well as some of the other posts here of pilots exhibiting the same problems, the most recent one averting a disaster due to superior piloting skills.

So.... since keeping oil off of the belly via a separator seems to be so important, I thought I would share with you the success I have had with the AirWolf Oul Separator.
I have installed it on 3 airplanes now, an RV-7A, and 2 RV-10's. Yes, the exact RV-10 that I had the problem with the Anti-Splat Aero device, so the comparison is valid. I have NO oil on the belly. NADA. Nothing. I only have to clean the lead off. The Airwolf device is the old Walker Separator, and it is very effective.
Yes, it costs a little more, but in the scheme of things like not blowing out the nose seal it seems like cheap insurance to me. And for those of you for whom NO oil on the belly is so important, this alternative works.

I have hundreds of hours on these, so it is not a 20 hours test and declaring victory.

I wish I had the money to cover the difference in price for all of you using the Anti Splat device as I would do it. But I haven't won that lottery yet.

I just wish you would not continue to jeopardize your aircraft, yourself, and perhaps your families/friends.

Vic
 
Snowflake said:
Now I need to go read up on high-key, low-key to see how they relate to what I do... :)
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Rob, it was not my intention to complicate matters by bringing up flameout pattern stuff from a previous life. The reason I brought up "low key" was to respond to a question as to why I flew the airplane like I did. I simply wanted to describe what was going on in my own head at the time. Basically, when the chips were down, I had an almost automatic unconscious reaction to go to my "happy place". Just like anybody else, training kicks in when needed, and most of my life I've trained to go to certain locations and altitudes relative to the landing point. That's all.

I'm certainly not advocating flameout pattern positions as "the" best way to land an airplane in trouble. It's just one of many ways to skin the cat. I don't think people should change the way they fly their airplanes if what they're already doing is safe and makes aeronautical sense.
 
vic syracuse said:
I haven't hadmuch luck in convincing everyone to remove these deivices, in spite of my own testing and experiences, as well as some of the other posts here of pilots exhibiting the same problems, the most recent one averting a disaster due to superior piloting skills.

So.... since keeping oil off of the belly via a separator seems to be so important, I thought I would share with you the success I have had with the AirWolf Oul Separator.
I have installed it on 3 airplanes now, an RV-7A, and 2 RV-10's. Yes, the exact RV-10 that I had the problem with the Anti-Splat Aero device, so the comparison is valid. I have NO oil on the belly. NADA. Nothing. I only have to clean the lead off. The Airwolf device is the old Walker Separator, and it is very effective.
Yes, it costs a little more, but in the scheme of things like not blowing out the nose seal it seems like cheap insurance to me. And for those of you for whom NO oil on the belly is so important, this alternative works.

I have hundreds of hours on these, so it is not a 20 hours test and declaring victory.

I wish I had the money to cover the difference in price for all of you using the Anti Splat device as I would do it. But I haven't won that lottery yet.

I just wish you would not continue to jeopardize your aircraft, yourself, and perhaps your families/friends.

Vic
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Vic,
Do you have any more info or possible a picture of the installed AirWolf unit? The Web site does not have much info/picture other than the item itself. I am interested.
 
vic syracuse said:
I just wish you would not continue to jeopardize your aircraft, yourself, and perhaps your families/friends.
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Hi Vic, I'm happy that you have found a solution that works for you. It is important for us to have confidence in the equipment we put on our airplanes. But I would caution that to conclude that airplanes and lives will be jeopardized because this equipment is installed is not accurate. The increased risk is caused when this equipment is not properly maintained.

I mentioned above that I had neither inspected nor cleaned the valve fitting for two years. What I did not write was how much I flew during that time. I flew 265 hours in two years without ever cleaning out the fitting as recommended by the manufacturer. I am quite confident that this oil separator will operate just fine and quite safely in the future if I inspect and clean it every 50 hours at oil changes.

The oil separator that you advocate is equally useful. Is it a maintenance free item? If it is indeed an install-and-forget item, then perhaps that added unique benefit would justify the hundreds of dollars of extra cost. Otherwise, I choose to stay with an oil separator that has a proven track record if properly maintained.
 
I disagree

Gash, I hear you but respectfully disagree with the statement that we KNOW if it is properly maintained it will work. I seriously doubt there is enough data and time yet to show that it will be as you stated. What we do know is that those of us who have put lots of time on it under varying conditions have demonstrated pretty clearly it has a failure mode that could be LESS than the usual oil change interval. I duplicated failures consistently at 30 hours on my airplane.

Could mine be different? Of course! So could every other one out there. I bet we find that some will fail with LESS time, and as engines age and have more blow by what could have been working at 50 hour intervals will now fail at less than that, and cause a serious unexpected problem for some one. I'll bet on it.

And everyone seems to forget that very knowlegeable people that we all respect tried this over 30 years ago and had the same problems. I know. I am getting the phone calls, and I have quoted some of them here with their permission.

As for the Air Wolf being maintenance free, I don't know that I would trust any item on an airplane to be completely maintenance free. I am not aware of any required maintenance, but I do clean it out every other year, mostly just to look inside. I've never found anything.

I will try to get some pictures as someone asked. Basically, it almost the same setup int hat it is mounted on the firewall and the drain is plumbed to the accessory case. There is an inlet hose that you attach to the rear baffles to pick up some pressure. In aircraft with vacuum pumps they use the outlet of the vaccum pump to supply the pressure. The outlet is quite large in diameter, about 1 inch or more, and it is attached to the firewall and is terminated about 4-6 inches ABOVE the cowling outlet.

Vic
 
Seems there is some muddying of the water here as it related to stand alone separators vs separators used with a vacuum valve setup?

Am I confused or are these not two separate items that can be combined or used separately?

Have there been any reports of failure modes with the AntiSplat air/oil separator when used as a stand alone unit (no exhaust mounted vacuum valve)?
 
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My apologies in Advance

So, here goes, and if Doug sees to it that I should be banned from this site, I am OK with that.

It is my very strong opinion that this Anti Splat device installed as recommended and plumbed to the exhaust systems will in fact fail at some point in time and may cause undo bodily or property harm. I have been living this for over a year. I called Allan a over a year ago and told him there was a problem. I was told I was the only one having this problem. Then I was told it was only on RV-10's. I spent over a year of my time and money thoroughly going over my engine, and then retesting, and I continually came up with the same results. And FINALLY, after it seems there are more people with some time on their aircradft, we are beginning to see the same failure modes. And I will bet that IF we continue to see people using it we will hear of more failures.

Most recently, someone on this forum almost got hurt. And it's nice for him to say it will work fine if properly maintained. What about the 2nd or 3rd buyer of the aircraft who knows nothing of this potential Sword of Damocles? And what about the person who is lulled into "it works fine with just cleaning it out every 50 hours" and then something changes that causes more blowby?? I will bet it will most definitely fail in a whole lot less time than the usual interval on that particular airplane.

I posted just recently of another RV-10 that came to my hangar and was just minutes away from a blown nose seal. And that owner (not a builder) said he had just cleaned it at the last oil change. Unwarranted confidence. And this person flies regularly at night and in IMC.

You are all being lulled into a death trap here. I have never felt so strongly about something like this in my entire life. Perhaps it is because I have lost some aviation friends who wouldn't listen and paid in full. Perhaps some of you have seen that as well.

I am justifiably fearful that one of our friends on this very site, or a buyer, is going to get hurt. I've been saying it for a very long time and it almost came home to roost this week. And I am not an "I told you so" person.

Just after my last post, I walked outside and the framed picture in my hangar reminded me, and I know most of you have seen it:

Aviation in itself is not inherently dangerous. But it is terribly unforgiving of any carelessness, incapacity, or neglect.

Vic
 
Brantel said:
Seems there is some muddying of the water here as it related to stand alone separators vs separators used with a vacuum valve setup?

Have there been any reports of failure modes with the AntiSplat air/oil separator when used as a stand alone unit (no exhaust mounted vacuum valve)?
Click to expand...

To muddy the waters further, my experience has been somewhat different.

Prior to installing the AntiSplat separator, I had a very small oil leak from my left mag mounting pad; perhaps a teaspoon over 4 hours of flight. Just enough to be annoying, and smear the belly. I was hoping the AntiSplat vacuum would stop/decrease my leak.

Because my welder of choice was not available for a while, I elected to omit the valve temporarily, and installed the drain hose just above the right exhaust pipe. After first flight I was disappointed to find my mag pad leak had increased significantly. Approximately 3-4 times what it had been originally. I also noticed minor oil leaks elsewhere that I thought were new.

I cleaned the engine thoroughly, added UV dye to the oil, and went flying. After shut down, I was surprised to find UV dye streaks not only from the mag pad, but also from virtually every mating surface and threaded fitting. Small streaks, but still there. This was very disappointing

I removed the AntiSplat, reinstalled the standard Vans breather, cleaned the engine again, and went flying. I am now back to my original minor mag pad leak, with no evidence of leaks elsewhere. I really wanted the AntiSplat to work, but it just didn't for me. Not sure why it didn't, but I am with Vic on this one.

Any one besides Vic have experience with the AirWolf on a -10?

Jim Berry
RV-10
 
N15JB said:
Because my welder of choice was not available for a while, I elected to omit the valve temporarily, and installed the drain hose just above the right exhaust pipe.
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The drain hose (1/4" nominal line) or the separator outflow hose (5/8" or 3/4" line)?

I'm guessing the 1/4" drain hose was plumbed to return separated oil to the crankcase, and you ran the large separator outflow hose to a position above the exhaust pipe.

Not that it matters. If you didn't pull a vacuum on the crankcase, how could the system be expected to slow your crankcase leak?

Given the situation, you won't like the Airwolf separator. As Vic noted, it taps upper plenum pressure (or vacuum pump outflow, if equipped), and actually pressurizes the crankcase. Typical crankcase pressure with a stock breather is less than 5" H20, with 1" being typical. The Airwolf system will result in a typical case pressure of 10"~15" H20 in cruise, more when you shove the nose down. Your leaks will get worse.

The above should not be taken as a endorsement of AntiSplat, nor as criticism of Airwolf. It is just an attempt at illustrating operating principles.

vic syracuse said:
Gash, I hear you but respectfully disagree with the statement that we KNOW if it is properly maintained it will work.
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Vic, Although I fully agree with the basic objection (we really don't know how long it might take to clog any given exhaust tap, as we don't yet fully understand the mechanism), I'd suggest that the installation of a relief valve greatly reduces the risk. Karl has done so.

Gash said:
Allan explained that he actually did previously send out a bulletin to all of his customers who bought the oil separator and vacuum valve. In fact, he spent considerable effort and expense on the mailings, so it was a serious undertaking on his part.
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ColoRv said:
Did anyone in here receive a mailing from Antisplat warning of this possibility? I know I didn't.
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I'd wager it to be a very rare document.
 
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DanH said:
The drain hose (1/4" nominal line) or the separator outflow hose (5/8" or 3/4" line)?

I'm guessing the 1/4" drain hose was plumbed to return separated oil to the crankcase, and you ran the large separator outflow hose to a position above the exhaust pipe.

You are correct; 1/4" hose to the case, and 3/4" hose to above the exhaust.

Not that it matters. If you didn't pull a vacuum on the crankcase, how could the system be expected to slow your crankcase leak?

I did not expect the system, without the valve, to decrease my leak. I was surprised that the leak increased.

Jim Berry
RV-10
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Gash - thank you for the elaboration in Post #47. All good reasons for the choices made and proven out by the outcome. Great job and thank you for sharing it all with us.
 
ColoRv said:
Did anyone in here recieve a mailing from Antisplat warning of this possibility? I know I didnt. But, thankfully....I do read far to much of these forums and knew of the danger. Still, for Alan to expect that every pilot would read these forums AND this thread which isn't titled to get the proper attention is foolish. I've said before and I'll say again, Alan is a great guy.... who will end up penniless if he doesn't stop putting out aircraft parts that aren't properly engineered and tested. Like Dynon's unforgivable delay in the freezing pitot tube fiasco....Alan shouldn't be sleeping until this is fixed or recalled.

With that said....the valve is still in mine, even though I did find more than a little build up of carbon in my saddle tube.
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No. I did not receive a letter.
I bought one of these units. Due to the location of my brake reservoir and battery, I could not put it where their instructions stated. (Nothing about maintenance in the instructions by the way).
When I called the factory to ask for a preferred alternate location, I was told "that is what we recommend, but, put it wherever you like, its your airplane." That ended the conversation.
It's for sale. Separator and valve kit. New, in the box, never installed, nor will it ever be on my airplane.....
I was going to sell it, but did not feel comfortable doing so. Same reason I never sold my Blue Mountain stuff, which I gave it to Stein so he could help others.
PM me an offer. At least I will know that you know what you are getting.....
 
Vic,

Don't sugar coat it ... Tell us how you really feel! :)

I think such direct talk is good all around.

This thread is the first time I've heard of fwd seal retention plates which initially sounded like a great idea. Then I started wondering why they weren't standard. Then I started wondering if there was a pressure build up and the front seal had retention plates where else might fail? Anyone know? The thrust seal may just be preferred to other potential options.

According to Alan Barrett, if we knew what was in the blow by we wouldn't return it into circulation, but that's his (learned) opinion. My open mind is starting to close.
 
woxofswa said:
Vic,

This thread is the first time I've heard of fwd seal retention plates which initially sounded like a great idea. Then I started wondering why they weren't standard. Then I started wondering if there was a pressure build up and the front seal had retention plates where else might fail? Anyone know? The thrust seal may just be preferred to other potential options.

According to Alan Barrett, if we knew what was in the blow by we wouldn't return it into circulation, but that's his (learned) opinion. My open mind is starting to close.
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On that note; I wonder why there isn't a built-in pressure valve into the top of the deep stick. It would certainly not hard to make it and regardless of separator or not, it would possibly save some disaster.

Vic,
I am glad you are you raising the concern. I can't think of any other motive other than a healthy concern for others.
 
another option

I've been trying to stay out of this, but here's my input. I've been watching all of these threads for months as I was doing my FWF. When I started I was going to put in the separator, but as the failures started adding up, I followed Ironflight's setup in his RV-3 with the Half-Raven tank hooked up to the breather. The breather is open out of the tank and vents onto the exhaust. In the 40 hours of flying I just did, the belly is clean even after multiple zero and negative G maneuvers. I've seen a few references to it on other threads, but it never seems to get much air time. Not sure why.

Ok, ya it's twice the cost of the other separator, but it's larger and works great, and in the grand scheme of things its not that much money.

http://www.ravenaircraft.com/cat_engine.html

RV-8 FWF by akarmy, on Flickr
 
I have tried to stay out of this one but its time to speak up. First of all I agree with Vic 100 percent. I would be one of the old timers that Paul Dye refers to. We tried almost the exact set up into the exhaust system with a PVC valve that anti splat is using many years ago with the same problems that are ongoing today. I had a partial failure of a crankshaft seal failure over the middle of nowhere Texas many years ago. No where near what Gash had but a failure none the less. I found the PVC valve itself to be the culprit with the valve having glued its self shut. We all eventually went back to venting the outlet from the exhaust back to overboard or over the exhaust pipe.
Alan was warned of this by a prominent figure in this group and failed to listen. I do believe that the Anti Splat air oil separator is a fine unit by its self. However there is no way to gage when a when a failure will occur with the valve or the coking at the exhaust port. Every engine is different Do your selves a favor and find a safer way before someone gets hurt. Enough said.
Ryan
 
Do your selves a favor and find a safer way...
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All valid points Ryan, thank you. What are your thoughts about installation of a relief valve as previously described? It seems to me that this is a very acceptable risk mitigation. Combine this with regular service intervals, and I believe the equipment becomes a safe system. I would be interested to read comments from others on this combination of risk control measures.
 
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Risk vs Benefit

Benefit = cleaner belly
Risk = engine failure

Let see, which one should I choose, this is a tough one :eek:
 
Why push your luck?

Gash, both you and Dan asked the same question. Why not just put the relief valve in as a failure mitigation. Let me ask it another way. Why install something in the first place that has a high probability of failure with severe consequences and count on the backup system to work?

I think there is a place for backup systems such as electrical or vacuum systems where they may fail and a backup system would make life easier but isn't mandatory. Here you are putting in a backup system that is mandatory and has to work 100% of the time when called upon. No exceptions. Are you willing to bet on that?

How about those who ride in the airplanes? My conscience won't let me and I certainly won't sign off any initial airworthiness inspections or condition inspections with one installed this way as I do not believe it allows a condition for safe operation. I think there is enough empirical evidence to prove it.

Vic
 
Walt said:
Risk vs Benefit

Benefit = cleaner belly
Risk = engine failure

Let see, which one should I choose, this is a tough one :eek:
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I'll second what Walt said.Not to go off topic but what about the oil seal retainer plates that screw on over the seal,I understand if enough pressure is there something is going to blow out,better oil under the ship then covering the windshield.
 
rhill said:
I'll second what Walt said.Not to go off topic but what about the oil seal retainer plates that screw on over the seal,I understand if enough pressure is there something is going to blow out,better oil under the ship then covering the windshield.
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Perhaps not necessarily. Restricted visibility aside there could be something said for the advantage of immediate notification of a problem that a messy windshield portends. A hemorrhage elsewhere may dump quicker and may not manifest itself until silence is imminent. Precious moments of a still powered diversion could be lost to blissful ignorance.
 
Im another who never received any warning letter.

I never received any warning letter. I too wonder how many fellow RVers who've installed this have no clue. I think a REAL effort should be made to let folks know the possible dangers. Im glad I just happened to log in tonight and see this thread.

After coming across this thread and spending hours ready the various links to past discussions, I will be removing the check valve.

[ed. Removed three sentences criticizing the management of this site. Please play nice! dr]​

Im so glad the outcome of this failure wasn't something being discussed because of a crash investigation and loss of life. I almost always have one of my children with me when flying and cant believe I could have put their safety in such jeopardy. Hopefully I find nothing plugged but am tempted to head to airport now to investigate because I know Im not going to sleep well until I know how plugged mine is.
 
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I respect the opinion of those posting the warnings quite a bit. I've got the relief valve installed, a clean primary valve in, and a manometer on the way (as mentioned in the other breather/separator thread). So I'll test for actual crankcase vent levels, then make a decision on whether to keep the vent valve installed or return to a separator-only set-up.

Very good discussion here, for sure.

Cheers,
Bob
 
I find this conversation strange...

Lets put something in my aircraft that has a known potential to kill me or one of my passengers just so I can have a clean belly. Oh, and I'll make my self feel better by checking it more often just to make sure its OK.
I have to say, you guys arguing to fly with one of these systems sure have some cajones.
The risk is simply to high gentlemen. We owe it to our passengers, to innocent bystanders (people on the ground), and to the aviation community to be RESPONSIBLE and make good decisions. This should be a very obvious decision to make.
Shame on the manufacturer of this product to not inform purchasers of the potential problem (as it sounds is what happened in this case).
You're not driving pickups down the road, you're flying airplanes. Make responsible decisions or we all pay eventually.
 
rvmills said:
I respect the opinion of those posting the warnings quite a bit. I've got the relief valve installed, a clean primary valve in, and a manometer on the way (as mentioned in the other breather/separator thread). So I'll test for actual crankcase vent levels, then make a decision on whether to keep the vent valve installed or return to a separator-only set-up.
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Same here Bob. I'm going to make my decision on the value of the separator based on hard test data points, and not on non data-driven opinion. Like you, I respect the ideas here from a collective hundreds of years of experience, but some well-intentioned posts seem to be extrapolating disaster from emotion, and that's a distraction as we try to sort out actionable facts from melodrama.

One thing I think is being glossed over here is the reliability of the NAPA 2-29000 check valve. As far as I can tell, this item is quite reliable. It's been around since the 1970s (or earlier?) and would qualify as "proven" technology. So it seems reasonable that if you tee this check valve into your existing breather hose, you've just provided a fully independent and extremely low risk alternate exit route for crankcase breather pressure.

In other words, it's essentially a second breather line. How is that a bad thing? You can dangle whatever experimental gadget you want from the original hose termination, and still have the same pressure relief capability as a plain traditional hose. You have not increased risk, you've just branched the line and kept the risk exactly the same as before. Therefore, the man who calculates cost-benefit and chooses the dirty belly has the same risk as the man who branches a "second" reliable breather exit.

Tell me where I'm wrong guys. I'm not emotionally attached to these ideas and there's no ego here. I just want to have a discussion that is careful with the facts and rigorous with what limited engineering data is available.
 
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Gash said:
Same here Bob. I'm going to make my decision on the value of the separator based on hard test data points, and not on non data-driven opinion. Like you, I respect the ideas here from a collective hundreds of years of experience, but some well-intentioned posts seem to be extrapolating disaster from emotion, and that's a distraction as we try to sort out actionable facts from melodrama.

One thing I think is being glossed over here is the reliability of the NAPA 2-29000 check valve. As far as I can tell, this item is quite reliable. It's been around since the 1970s (or earlier?) and would qualify as "proven" technology. So it seems reasonable that if you tee this check valve into your existing breather hose, you've just provided a fully independent and extremely low risk alternate exit route for crankcase breather pressure.

In other words, it's essentially a second breather line. How is that a bad thing? You can dangle whatever experimental gadget you want from the original hose termination, and still have the same pressure relief capability as a plain traditional hose. You have not increased risk, you've just branched the line and kept the risk exactly the same as before. Therefore, the man who calculates cost-benefit and chooses the dirty belly has the same risk as the man who branches a "second" reliable breather exit.

Tell me where I'm wrong guys. I'm not emotionally attached to these ideas and there's no ego here. I just want to have a discussion that is careful with the facts and rigorous with what limited engineering data is available.
Click to expand...

Good summary, and the most likely failure seems to be plugging, and the tee addresses that, should the maintenance interval not be within proper range. I suppose if we got some engine hours vs crankcase pressure, then we could develop a maintenance interval that yield a 98% (or so) probability of success. A crankcase pressure alert could also work, if we knew the blow-out pressure of a front seal.

With the oil change cleaning and pressure relief tee, a pressure switch is probably not needed.
 
Great write up Karl,
You did a great job. Emergencies usually take us all by surprise. You can practice and practice but when it happens all that training goes into dead cells for awhile until you get your cool back.

Prop seal.... leaking yes but blowing out Wow you did a great job. I guess that nearest airport feature is a great feature.

Smilin' Jack
 
... I have started a new thread in this discussions area addressing this titled;ASA Vacuum System Concerns. I started a new one so it doesn't get lost in a large discussion. This should be considered a
SERVICE BULLETIN
 
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Gash said:
...One thing I think is being glossed over here is the reliability of the NAPA 2-29000 check valve. As far as I can tell, this item is quite reliable. It's been around since the 1970s (or earlier?) and would qualify as "proven" technology...
Click to expand...

I wouldn't put a great deal of stock in the proven reliability of that valve, unless it is known that the quality of manufacture hasn't changed over the years.
FWIW, NAPA is now a Chinese company :eek:
 
Check for crankcase blockage

Ice can form around your crankcase tube and block this passage. Things will start to freeze up this time of the year. Pilots beware! Blew the crankcase seal on my Starduster II this way.
 
Vent tube

Jeff Hagg said:
Ice can form around your crankcase tube and block this passage. Things will start to freeze up this time of the year. Pilots beware! Blew the crankcase seal on my Starduster II this way.
Click to expand...

This is a problem that dates back to at least the mid 60's and in many cases has nothing to do with a check valve.
Around 1964 Piper started slotting the aluminum tube near the top to provide relief if the lower end of the tube froze up. At the time no one understood what the slot was for. On the Pitts as well as most aerobatic aircraft with a Christen type inverted oil system, it is normal to run the vent tube all the way back to the tail. Pitts provides an alternate tube for cold weather operation that vents to the bottom of the firewall. I flew my Pitts a few times in freezing temperatures with the tail outlet, never had a problem.
The vast majority of the posts on this subject ignore the fact that the Lycoming nose seals blow out for a variety of reasons, many of which have nothing to do with the check valve. Improper installation of the seal its probably a much greater problem than clogged check valves.
 
OK, no flame intended here at all?just more discussion

Honestly, in one sense, ice blocking a non-whistle-slotted breather, or an improperly installed nose seal, as causes of seal blowouts, while certainly possibilities, are a bit like distractors to the coked-up CVV stem discussion?yet they both add value to the discussion. That may sound like playing to both sides of the aisle, but its not?

Sure, they could each cause a blowout, but I've not heard anything from Gash to indicate he suspected the latter, and the former is a non-player in his system set-up.

Talking about the ice build-up is a good reminder to those with standard breather tubes?something to check as we head into winter (cleanliness, mounting, whistle-slot integrity.

Crank-seal installation?Gash, I have some gouge for ya, if you do this yourself.

But the CVV stem coking needs to remain the focus, so folks can be eyes-open on the issue. I say this, and I do still have mine installed?with open eyes.

My discussion here is about my experience, and may or may not be related to Gash's experience. I had what sounds like a similar level of blockage in a much shorter time...about 4 months and 70 hours (slower winter months). My engine is a 540, though not in a 10. My CVV was also broken inside. I did not have a seal blow out, and initially wondered if Gash's being coked up, down to a 1/8" hole, could cause a seal blowout. Not questioning his diagnosis, I say this as a rhetorical question of "what size hole causes a seal to blow?" There's probably a lot of "it depends" in there, and seal installation quality likely is a "depends" factor. Another interesting finding has been that since that time, I've inspected at oil changes and during other cowl-off maintenance, and have not seen anywhere near that speed or severity of coking. Very minor build-ups near the weld on my DIY saddle. Not sure why, and I don't know if coking starts slow, then accelerates as the clog gets large, but I have seen only very insignificant deposits since that first major clog. Since my clog occurred in winter, I will be watching closely this winter as well, to see if it gets worse again?just for a data point. No idea if cold weather has any significance at all though?just data seeking.

In my case I did chase leaks, and changed the nose seal twice?once before the AOS/CVV was installed, and once after. The seal leak was worse on the first swap, in which I replaced a split seal with a split seal. I felt I was diligent in the first installation (my knuckles bore the brunt of my diligent cleaning of the crank bore!). It held for a while, but began to leak again, though not as badly. During that time, I did install the AOS and CVV. My impression was that my oil leaks did seem to increase slightly after the install, but can't say how long after?very non-scientific swag.

Did the nose seal start to leak again due to the coking, I dunno?certainly possible. I do know that I got some additional advice from Lycon on the second seal swap; used a one piece seal, did a better job of sanding a helical pattern in the bore, and used Lycon's recommended Scotch Weld 1300 glue, versus Ace-bought Pliobond, on the second go-round (and my knuckles were even worse off). So I can't point to the CVV as the only culprit, and I don't think my head is in the sand. I also changed two prop governor gaskets, one oil return line, and chased and chased this, both before and after the CVV was installed. Even found a cracked (and poorly repaired) old oil breather adapter fitting.

After I found the coked stem, I went to a regular inspection interval, as described above. Still had some pesky oil leaks though, and replaced an oil cooler line, then the oil cooler, which had developed an internal leak (with a consistently clean CVV stem).

The last 10 hours have shown the cleanest cowl innards I've had for a while, but that is a very short sample size. Still watching closely, keeping the valve/stem clean, and have the 2 NAPA valves installed. I would like to test for the vent vacuum amount being provided, and will do so to add to this discussion. The clean belly concept has never been a big factor for me in this, though cleaning only smoke oil residue off the tail would be kinda nice! And if there is no vacuum, I'll work with Allan to see why, and see if it can be improved. I'll provide him candid feedback, good or "other", and post here too.

Cheers,
Bob
 
rvmills said:
But the CVV stem coking needs to remain the focus, so folks can be eyes-open on the issue.
Click to expand...

Eye on the prize-----thanks for keeping things on track

rvmills said:
I did not have a seal blow out, and initially wondered if Gash's being coked up, down to a 1/8" hole, could cause a seal blowout. Not questioning his diagnosis, I say this as a rhetorical question of "what size hole causes a seal to blow?" There's probably a lot of "it depends" in there,
Click to expand...

Thinking about this, the coke buildup itself may well be a limiting factor----------it takes some oil to be baked into the coke, right??

As the hole closes up from the coke, what happens to the available vacuum, and the flow of oil???

I wonder if there is a spot where the buildup will limit the oil flow to where there will be no more buildup----------yet there will still be a small opening???

Can the coke actually close off the hole entirely ????

Now back to your regular programing.
 
Clean the belly

I couldn't agree more with Pierre, I'll keep the vent tube open and clean the belly. Better to clean the belly than lose the plane.
 
Reality says the informed will make their own choice.

The real issue involves getting the word out about coking the exhaust tap, so the uninformed will not descend from the heavens in a shower of oil.
 
rvmills said:
OK, m . . . "what size hole causes a seal to blow?" There's probably a lot of "it depends" in there . . .

Cheers,
Bob
Click to expand...

Really good question! It also probably depends on how much blow by there is. Also, as rings rotate etc, does the blow-by change, wander with time? Probably.

Bob, As you check the crankcase pressure would it be possible to install an orifice of a couple of sizes to see how the pressure changes? I bet that is already in your test plan :D

I gotta get finished and flying so I can provide some data too.
 
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