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  #21  
Old 04-26-2016, 05:54 PM
1001001's Avatar
1001001 1001001 is offline
 
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Location: Just Minutes from KBVI!
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Default

Quote:
Originally Posted by jrs14855 View Post
You seem to be running out of possibilities. Even though you say you checked the hose I would replace it with a hose made by a reputable hose shop. It is possible you have a flaw in the hose that you missed on a visual inspection.
What is the volumetric flow through these lines? If it is high enough, there is a possible failure mode in which the inner liner of the hose delaminates. Then when liquid flows past it a local low pressure area can suck the liner inward and actually obstruct flow. When flow is removed, the "bubble" goes back to normal and is very difficult to visually detect. I have seen this happen with hoses and also with rubber lined piping systems.

If there isn't much flow in this line, this failure mode would probably not apply because the local pressure would not drop low enough.
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  #22  
Old 04-26-2016, 06:43 PM
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Bayou Bert Bayou Bert is offline
 
Join Date: Sep 2012
Location: Prairieville, LA
Posts: 223
Default Not a High Flow Rate

The flex hose I have, that runs from governor adapter to the
prop, is a SS rated at 1500 psi. It too is new with 14 hrs of operation.
The leak down test by Lycoming requires the governor to be removed.
Then a plate is bolted on in place of governor. It has been tapped so
the same gauges you check the compression with can be hooked to
the plate. This allows your to pressure the prop circuit. The procedure
call for 40 psi on first gauge from compressor. The specs showing amount
of leak down on second gauge are 6 to 35 psi. Anything inside that range
is considered good.
Based on these numbers I would say the flex is more pressure than flow.

Plate for governor is being made and I hope to be able to do the
procedure Friday morning.
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  #23  
Old 04-26-2016, 06:49 PM
BillL BillL is offline
 
Join Date: Sep 2007
Location: Central IL
Posts: 6,320
Default

Quote:
Originally Posted by Bayou Bert View Post
The flex hose I have, that runs from governor adapter to the
prop, is a SS rated at 1500 psi. It too is new with 14 hrs of operation.
The leak down test by Lycoming requires the governor to be removed.
Then a plate is bolted on in place of governor. It has been tapped so
the same gauges you check the compression with can be hooked to
the plate. This allows your to pressure the prop circuit. The procedure
call for 40 psi on first gauge from compressor. The specs showing amount
of leak down on second gauge are 6 to 35 psi. Anything inside that range
is considered good.
Based on these numbers I would say the flex is more pressure than flow.

Plate for governor is being made and I hope to be able to do the
procedure Friday morning.
Good to hear, Bert. I made a crude plate to cycle my prop in place. It should be easy to perform the test.
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  #24  
Old 04-26-2016, 07:07 PM
Bob Kuykendall's Avatar
Bob Kuykendall Bob Kuykendall is offline
 
Join Date: Sep 2006
Location: Vallecito, CA
Posts: 593
Default

Quote:
Originally Posted by Bayou Bert View Post
The flex hose I have, that runs from governor adapter to the
prop, is a SS rated at 1500 psi. It too is new with 14 hrs of operation...
I think that the issue that 1001001 and others are trying to raise is that there are a variety of failure modes in flexible hoses besides bursting. I've also seen flaps of rubber get cut off of the ID while fitting the ends that later cause intermittent problems.

Thanks, Bob K.
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  #25  
Old 04-26-2016, 07:28 PM
1001001's Avatar
1001001 1001001 is offline
 
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Default

Quote:
Originally Posted by Bob Kuykendall View Post
I think that the issue that 1001001 and others are trying to raise is that there are a variety of failure modes in flexible hoses besides bursting. I've also seen flaps of rubber get cut off of the ID while fitting the ends that later cause intermittent problems.

Thanks, Bob K.
That's the idea. An additional failure mode related to the one I mentioned above is that if the inner liner of the hose becomes delaminated, it can kink and obstruct flow even when the outer part of the hose is smoothly curved and appears undamaged.
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  #26  
Old 04-26-2016, 08:42 PM
jrs14855 jrs14855 is offline
 
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Location: Lake Havasu City AZ
Posts: 2,641
Default Hose

Quote:
Originally Posted by 1001001 View Post
That's the idea. An additional failure mode related to the one I mentioned above is that if the inner liner of the hose becomes delaminated, it can kink and obstruct flow even when the outer part of the hose is smoothly curved and appears undamaged.
That is exactly what I was suggesting. At this point I would be trying a different hose. Try to find a hose that is rated 3000# even though the pressure in the governor line is way below that.
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  #27  
Old 04-26-2016, 09:01 PM
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Bayou Bert Bayou Bert is offline
 
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Location: Prairieville, LA
Posts: 223
Default Path Forward

If the engine passes the leak down test Friday, then based on Bob, Dave and Jim's post on the the flex hose,
the flex line will be removed and a solid SS line installed. Don B aka Cajunwings has one for his O-320/CS
he's not ready to use yet on his 9 rebuilt.
I will then go and fly the same profile, as best as I can, that I used to made the charts.
Then if that does not solve the problem, Don has offered his prop, same as
mine, to try and finally nail down my prop as the problem.

My spinner will not fit Don's prop. If I try Don's prop, does anyone see any problems
flying without the spinner?

First goal, pass leak down test Friday.
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RV-9A known as Pearl Sold
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Last edited by Bayou Bert : 04-27-2016 at 05:05 AM.
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  #28  
Old 04-27-2016, 01:20 PM
ilj22901 ilj22901 is offline
 
Join Date: Sep 2013
Location: Charlottesville
Posts: 2
Default Prop problem

I have a friend that had CS prop problem that was traced to the large thrust/crankshaft bearing. It was not perfectly installed or shifted and when the fixed pitch prop was replaced with a CS it caused rpm problems. I guess that is what the leak down test is for.
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  #29  
Old 04-27-2016, 02:45 PM
jrs14855 jrs14855 is offline
 
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Location: Lake Havasu City AZ
Posts: 2,641
Default Thrust Washers

My 0 320 with Lycoming case does not have thrust washers. Some of the clones do.
Front main bearing clearance, rear plug integrity and thrust clearance can all affect leakage.
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  #30  
Old 04-30-2016, 05:44 AM
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Bayou Bert Bayou Bert is offline
 
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Location: Prairieville, LA
Posts: 223
Default Test Update

Shot of Test Plate I had friend make. It is bolted on in place of the
governor.


I made a bunch of mistakes on the test. First I didn't have any help.
I didn't tighten the bolts that hold the plate enough. So when I was
warming the engine I could not see the plate. Oil everywhere. I did put
a flare fitting at the gauge port and ran tubing up above and installed
gauge where I could see it from the cockpit. The 100 psi gauge rapped out
against the stop indicating way over 100 psi. Bought from Grainger and it is
a 100 psi.
Warmed oil to 110 degrees and all cylinders just over 300. But after
shut down and cleaning all the mess up found second mess up. I should
have removed the plug for the prop circuit and installed the female side
of quick connector for the test gauges. Soooo, but the time I FINALLY
connected the gauges and added air, the engine had cooled a good bit.
When I first applied the 40 psi, the gauge on the prop circuit when up to
almost 40 psi while it was pushing oil out of the transfer line and other
areas. It then settled down around 30 psi which indicates a good test.
Lycoming said it should be between 6 and 35 psi.
Still not sure why pressure on gauge was so high if true.
BUT...as I just left the air running, over time of about 20 minutes
the pressure on the prop circuit declined to below 6 psi. If I moved the
prop around, it would go back above 6 psi then go back down. Lycoming
does not give a time factor on the test. I assume the air cooling down
the bearings etc reduced the back pressure...right?

So today, if I can beat the coming storms, going to go back and
1. Check plate for tight once more.
2. Leave quick connect installed with hose removed. Can't think of any
reason not to do this since there should be no pressure on that circuit.
3. Install another cheap gauge but 0-200 psi this time, just to see.
4. Warm to 110 degrees oil temp.

Then immediately on shut down hook up gauges and apply 40 psi to
prop circuit. AND see what new gauge shows for oil pressure.

We'll see.
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