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  #81  
Old 10-28-2014, 07:19 PM
carolsyracuse carolsyracuse is offline
 
Join Date: Oct 2006
Location: locust grove, ga
Posts: 139
Default 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
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  #82  
Old 10-28-2014, 07:23 PM
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strahler13 strahler13 is offline
 
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Default

[quote=Walt;928731]Risk vs Benefit

Benefit = cleaner belly
Risk = engine failure

I think Walt hits the nail on the head in six little words..
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  #83  
Old 10-28-2014, 07:55 PM
rhill rhill is offline
 
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Location: Valley Forge, Pa
Posts: 636
Default

Quote:
Originally Posted by Walt View Post
Risk vs Benefit

Benefit = cleaner belly
Risk = engine failure

Let see, which one should I choose, this is a tough one
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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  #84  
Old 10-28-2014, 09:23 PM
woxofswa woxofswa is offline
 
Join Date: Sep 2007
Location: Mesa Arizona
Posts: 608
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Quote:
Originally Posted by rhill View Post
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.
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.
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  #85  
Old 10-28-2014, 11:13 PM
badmrb badmrb is offline
 
Join Date: Oct 2009
Location: Pomona, ks
Posts: 77
Default 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.

Last edited by DeltaRomeo : 10-29-2014 at 08:37 PM.
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  #86  
Old 10-29-2014, 12:28 AM
dhmoose dhmoose is offline
 
Join Date: Jun 2010
Location: Portland, OR
Posts: 337
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Quote:
Originally Posted by Walt View Post
Risk vs Benefit

Benefit = cleaner belly
Risk = engine failure

Let see, which one should I choose, this is a tough one
I thought I was in the twilight zone until this was finally mentioned! Thanks Walt.
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  #87  
Old 10-29-2014, 01:31 AM
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rvmills rvmills is offline
 
Join Date: Nov 2007
Location: Reno, NV
Posts: 2,125
Default

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
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  #88  
Old 10-29-2014, 06:08 AM
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aarvig aarvig is offline
 
Join Date: May 2008
Location: KANE, Hugo, Minnesota
Posts: 765
Default 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.
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  #89  
Old 10-29-2014, 08:46 AM
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Gash Gash is offline
 
Join Date: Aug 2009
Location: Goodyear, Arizona
Posts: 877
Default

Quote:
Originally Posted by rvmills View Post
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.
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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Last edited by Gash : 10-29-2014 at 09:12 AM.
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  #90  
Old 10-29-2014, 11:26 AM
BillL BillL is offline
 
Join Date: Sep 2007
Location: Central IL
Posts: 5,516
Default

Quote:
Originally Posted by Gash View Post
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.
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.
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RV-7
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“I often say that when you can measure what you are speaking about,
and express it in numbers, you know something about it; but when you
cannot measure it, when you cannot express it in numbers, your knowledge
is of a meager and unsatisfactory kind.”
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