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  #11  
Old 12-31-2018, 05:01 PM
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Mike S Mike S is offline
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Quote:
Originally Posted by rvbuilder2002 View Post
There will always be a certain amount of leakage (there has to bee since the oil feeding the main bearing has to go somewhere). There is a specification for the amount of leakage allowed. The test is done using a Cyl differential pressure tester just like is done when checking cylinders. If pressure delta is outside of the allowed range, it is a sure indication that something in the nose section is not right (excessive bearing clearance, missing plug, etc.)
Possibly this?? http://www.vansairforce.com/communit...3&postcount=13
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  #12  
Old 12-31-2018, 06:45 PM
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Quote:
Originally Posted by rvbuilder2002 View Post
Since it didn't look like either of threads that Axle linked to have the information I am adding it here......
There is a Lycoming service instruction (don't remember the # right now) that documents a specific procedure for testing the nose section of a constant speed engine.
There will always be a certain amount of leakage (there has to bee since the oil feeding the main bearing has to go somewhere). There is a specification for the amount of leakage allowed. The test is done using a Cyl differential pressure tester just like is done when checking cylinders. If pressure delta is outside of the allowed range, it is a sure indication that something in the nose section is not right (excessive bearing clearance, missing plug, etc.)
Lycoming Service Instruction 1462 Propeller Oil Control Leak Test Procedure (With Propeller Installed on Engine) is the test Scott is referencing. [Link is valid when I post this. IF link is broken search for the name as I did a copy / paste.]

Lycoming Service Instruction 1435 (Conversion from Constant Speed to Fixed Pitch Propeller and Vice Versa) tells how to convert to constant speed providing you do not have the problem that Axel did.
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  #13  
Old 01-01-2019, 04:13 PM
sblack sblack is offline
 
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Quote:
Originally Posted by Boyd Birchler View Post
Converted a 0-360 A4M to a hollow crank from it's original solid crank.

Have not always been lucky: had a C90 Continental that would not get oil pressure, had the engine off the plane twice before finding the culprit: 6 little #10 machine screws were left out on the front of the camshaft....
I had that one. I replaced the cam with a rebuild and it was slightly different and had those holes for a vacuum pump gear I think. Oil just pees through them from the gallery on one side of the engine and doesn't get to the other side. My engine builder figured it out and had the engine off, fixed and back on in a few days but damned frustrating after a rebuild.
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  #14  
Old 01-14-2019, 11:44 PM
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Well, it has been a long troubleshooting event. Leading down multiple rabbit holes.

Background info: I removed the engine from the plane to access the firewall for the governor cut out and also to send it in to an engine shop (name held on purpose). As the engine was already at the shop I asked the shop to convert it to constant speed. They said no problem.

Bad Assumption: Everything should be working, they are professionals.

Trouble shooting:
After I did the test with the air on the 90 degree fitting (nose of the engine that gets the governor line), I started researching on VAF and other sites. That lead me down the path of the hole or no hole, NPT plug or not.

in order to confirm the problem, I tried to prove that saying of "insanity is doing the same thing over and over again, but expecting different results".

in this case, I was not insane. The results would differ and were not predictable. Sometimes I would put 40 psi of air in the plug and the prop would move. Sometimes i would cycle the prop a few times with the engine running and it would work. Then it would not work after a certain number of prop cycles. Sometimes it would work if I "double pump" the prop lever is my RMP was at 2200. Seemed like it always failed to cycle at around 170 deg of oil temp. All that took time to diagnose and collect.

I designed a pressure differential tool that would work just like a cylinder compression tool. I would put 40 psi of air in the 90 deg fitting and read the actual pressure in the system. Sometimes the tool would real 22-24 psi and the blades would move; and some times the 40 psi was going straight out of the crank case vent without any prop movement or pressure.

Talked to a local A&P and he said I should instrument the governor to check the pressure. So I contacted the PCU5000 folks for guidance on how much pressure I should see at what governor rpm. They told me that max pressure of 320 psi plus/minus 20 happens as low as 1700 governor rpms. So 1700 times the governor ration of .866 gave me the engine rpm required. at 1600 ish engine rpm i should have a good check of governor pressure and not blow the gauge to the moon. I ran the engine at 1600 rpm and the pressure gauge read 350 psi. I called that good as the calibration on the gauge was not checked for accuracy prior to using. we just knew it work as they A&P uses it to check pressure in the fuel/oil lines he makes. Pics below of the set up.





I then designed a governor pad test plate on Solid Works using the Lycoming Service Instruction 1462. Once that was done, I used my 3D printer and made the plate. Aircraft Spruce wanted over $2000 for that part. It cost me about $4 in plastic and 45 minutes of computer time. Following the service instruction I was still getting inconsistent readings for pressure. Same as with the pressure differential tool i made for the 90 deg fitting. Pics below. Forgot to take a pic of the actual part.






The next logical step was the crankshaft plug. Even though i visually looked at it before I put the prop on. So I ran the engine and sure enough, prop worked fine for approx 20 minutes of cycling. I ran it until it stop cycling, then shut it down. interestingly enough, oil temp was 174 deg (i use Aeroshell 100 Plus).

Next step was to pull the prop. One buddy kept telling me that I left a plastic plug in. That was not it. But I kept thinking that some of the problems ("double pump" on the prop lever, oil temp at 170 deg) were pointing at partial blockage or poor seal of oil in the crankshaft or crank case. I found a gentleman (thread on VAF) that said his crank case broke a piece inside that was improperly manufactured. I was hoping that was not the case. Prop came out and i found this.

WTF?! is that plug crooked? Is that rust? When I first looked at the plug I remember thinking, "why would the shop not clean the inside of the crankshaft?".


So I grabbed a wooden dowel, put it on the plug, and tapped gently. The plug came right out. Double WTF.


I pulled the prop extension so I could get the plug out and this is what I found. A USED AND RUSTED PLUG INSTALLED.


Continue on next post due to posting limitation.
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Last edited by AX-O : 01-15-2019 at 12:21 AM. Reason: spelling
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  #15  
Old 01-14-2019, 11:45 PM
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After I was done with the disappointment, I went to the local A&P and asked if he had a new plug i could barrow. He happen to have one left, part number SL61510. He told me that you can't reuse those plugs because they tend to pop out. While I was cleaning the inside of the crankshaft to make sure I got a good seal, one of our local guys showed up with a home made kit of all sorts of stuff. He also had an issue with that plug in his plane. He happened to to to our A&P and found out I was fighting a similar issue. After a little TLC on the tool, the new plug was back in.





Put the prop back on and waited a week to do ground runs as I ran out of weekend.

The following week I did ground runs and thing were working as expected. Finish putting the plane back together and then had to wait a day for rain. Are you kidding me? It rains here 3 days out of the year. Last time the plane flew was in Jul!!

The next day came and I was prepared. Did many risk mitigation things to stack thing on my side.
pics before heading out.


New nose


One of the potential issues on the first take off would be prop overspeed. So in order to mitigate that, I used the new EICommander and limited the RPM to 2800ish. That would cut the ignition out of the picture until the rpm would drop below 2800ish. Not ideal but a mitigation. I also thought about corrective actions if it happen. So throttle back to half way from full, climb expressively to slow the prop rpm and land straight ahead (7100 ft runway). But it would all start with the takeoff and feeding throttle slowly so the governor would have a chance at working before going full power.

Take off was uneventful. rpm went up to 2720, then down to 2680 and remained at 2710 while at full power. The rest of the flight was also uneventful. I flew a 0.6 and landed to check things out. Things seem to be ok but I am not calling it yet. Want to make sure the dang plug remains in. I am back in Phase I for 5 hrs. Pics after landing



Well.....This one hurt in so many levels. I almost threw in the towel. I hope this post scares you into doing some research first before going down this road. I also hope it will save you all the pain, money and time that I had to spend. So I guess tomorrow I will be calling the engine shop to tell them I don't have to pull the engine and they don't have to fix it.
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RV-4 fastback thread and Pics
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The information that I post is just that; information and my own personal experiences. You need to weight out the pros and cons and make up your own mind/decisions. The pictures posted may not show the final stage or configuration. Build at your own risk.

Last edited by AX-O : 01-15-2019 at 12:20 AM. Reason: place holder while i typed the rest of the post
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  #16  
Old 01-15-2019, 07:47 AM
BillL BillL is online now
 
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Sorry, I am a little confused about the actual issues and timeline.

Did this engine have both the case oil return plug AND the internal crank plug problem for this conversion to CS prop?
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  #17  
Old 01-15-2019, 08:24 AM
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Quote:
Originally Posted by BillL View Post
Sorry, I am a little confused about the actual issues and timeline.

Did this engine have both the case oil return plug AND the internal crank plug problem for this conversion to CS prop?
Just the crankshaft plug.
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  #18  
Old 01-15-2019, 10:08 AM
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Bayou Bert Bayou Bert is offline
 
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Great job Axel, I too had a similar problem with CS prop.
Engine built by rep firm for CS. When time to fly, found that
the engine/rpm would surge. Prop could not take changes to throttle,
lift off etc without surging. Had prop and governor checked, all good.
Finally after comparison, found that my crank did not have the cross tube
at the oil entry point like you show in one of you pictures. I only had one
hole in the wall of the crank was in that area. A longtime Lycoming engineer explained
that without the cross tube, no way to get air out of oil. When crank is spinnning the oil goes
to the outside, due to weight, air to center, exactly where slot/hole is in the cross tube.
Once crank was swapped out, any hint of surge completely gone.
Feel your pain and the timeline it takes to find something of this type.
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  #19  
Old 01-15-2019, 10:33 AM
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We’ve all been there Axel - identify a problem, come up with a plausible cause, and then we tend to lock in on that cause. So its always good to get some out of the box thinking goign on. AS we used to say in the space business “the first answer is always wrong!” Sometimes its not, of course, but its good to look far and wide for possible causes.

And Occam’s Razor is almost always right....

Glad you’re up and flying! The C/S prop makes a huge difference on teh -4...I think Dayton loves his - I sure liked it when I flew it.
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  #20  
Old 01-15-2019, 10:46 AM
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Axel,
I too feel your pain.
Some years ago I was converting a FP to CS and turns out the front clamshell bearing was "out of place" one side had jumped up on the dowel pin, just enough to take up all the clearance of the bearing so it ran but allowed the oil to run under and not build pressure.

The real problem was I am not as smart as you are and I struggled to get good info about trouble shooting as most A&P's have never run into anything like it. But, just like you, I kept eliminating possible problems and with the help of a SB, I pintointed the problem to the "nose" and tore the engine down to find the problem......heck of an education.
Congrats on resolving the issue and educating us on the issue.
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