Lycoming prop oil control leak down test

Reaching out to see if any one has the tool already on hand to preform the leak down test as described in SB 1462A.

I have had an on going issue and really need to see if my recently overhauled engine is the problem.

https://www.lycoming.com/sites/default/files/Propeller Oil Control Leak Test Procedure.pdf

Tired of being grounded,
Ryan
Thanks.

From what I have seen in the past, the most common problem detected with this test is failing the leak down test (#7) of the nose section of the engine.

This part of the test can be done without the test plate by adapting a cyl differential pressure tester to connect directly to the line fitting on the nose of the engine. Testing this way wont check for obstruction caused by a plugged line or incorrectly installed gov. drive gaskets, but it will detect if the nose section is the problem (I think there is an internal plug that can be accidentally left out which will make the prop pitch control non functional).

What is the issue you are experiencing??

Prop Gov issue

Ryan: Details please.



Don Broussard
RV9 Rebuild in Progress
57 Pacer

A little back ground. Last August I discovered large bits of metal in the oil sump screen. Upon tear down of the engine we found the center main barring coming apart. I sent the engine off to Tulsa to BPE for an overhaul. All work was performed to new overhaul standards by BPE, Aircraft Specialties, etc.. Then I relocated myself from Indy to South Florida to flight instruct for six months. It wasn't until Feb that my engine returned from BPE. I also decided to purchase the new HRT Prop from whirlwind. (My previous prop, on the same engine btw, was a hartzel).

I came back in Indy for a week in Feb and installed the engine and prop in a very cold hangar.

On my first take off I hit 2750 RPM and had to pull the power back to prevent it from further over speeding. On climb out I typically reduce to 25/2500, which normally only takes a few little half twist of the knob. But this time I turning and turning with little drop in RPMs. I stayed above the airport for a few laps and noticed I wasn't getting much movement on the blades. Descending from 3000 ft the RPM hit 2750. RPM was not being held with multiple power changes and/or altitude changes.

Suspecting maybe a prop governor issue I elected to swap out my freshly overhauled Hartzell prop gov with a new Joihostol.

Second flight with the new gov and I had the exact same issue. During runup when I cycled the prop it took 4 or 5 seconds and the RPM slowly dropped about 300 rpm.. I took off and saw 2650 and could only get about half throttle to prevent over speed. As soon as the wheels came up I hit 2800. I only flew the pattern once and landed as I knew there was still a problem.

That was Feb.. I just returned home a few weeks ago.

I have since sent out the prop governors to Bill at WW for bench testing. He said the Hartzel gov was not acting right but the Johistol is. I have been waiting for them to be returned to me and expecting them any day now.

I have checked the prop gov line. I have the flex kind. I did find that one end of the hose was 1 size smaller fitting than the other. Although, it has always been like that, I corrected this thinking maybe the new WW prop is more sensitive than my prior Hartzel.

I removed the prop to ensure there wasn't a rag or something jammed in the crank shaft. There wasn't... Also, my crank does have the slot with a hole in it...

Once I get my governor back the next step, is to do the leak down test. I believe I will first do it without the special plate in SB 1492a. (So far the cheapest quote from a machine shop to make one was 300.00.) If it fails this test then I guess I have to pull the engine off and send it back to Barrett. If it passes, then I have no idea what to do.

Engine is IO 360 A1A narrow deck

Any other thoughts would be appreciated.

Scott in post #2 is correct! If you can read the service letter, it actually says it.
I had this problem after converting from FP to CS and actually found a problem in the nose of the engine by doing this SI. My issue was not the "missing plug" but actually was the clam shell bearings had shifted during assembly and was half on and half off the alignment pin, allowing the pressurized oil to escape under it, back into the crankcase. The 600TT engine a complete overhaul. :-(

I made the adapter plate from scrap aluminum purchased from a dealer, from their scrap bin. It does not have to look pretty, I used a jigsaw and drill and taps.

Pulling the engine is pretty serious, but after you have tested "everything" and the only issue is isolated to the "nose"...it is the only thing left!

Email sent too...

I finally was able to complete the leak down test described in SI 1462a and it failed. I did the test twice. The first reading was about a 3 or 4. Then I ran it up again to warm the engine/oil again and the reading was a 1 or so.

Prior to doing the test I switched out my new WW prop and put my old hartzel prop back on. I did a runup to 2000 rpm and this prop would not even cycle. I left the prop lever full aft for 30 or so secounds, 7 or 8 times. Nothing, where as the WW prop would cycle, just very very slowly.

Not sure exactly what the low PSI reading means, other than it is unacceptable.
Looks like the motor is going to have to go back to Barrett.

miyu1975 said:

I finally was able to complete the leak down test described in SI 1462a and it failed. I did the test twice. The first reading was about a 3 or 4. Then I ran it up again to warm the engine/oil again and the reading was a 1 or so.

Prior to doing the test I switched out my new WW prop and put my old hartzel prop back on. I did a runup to 2000 rpm and this prop would not even cycle. I left the prop lever full aft for 30 or so secounds, 7 or 8 times. Nothing, where as the WW prop would cycle, just very very slowly.

Not sure exactly what the low PSI reading means, other than it is unacceptable.
Looks like the motor is going to have to go back to Barrett.

Click to expand...

Ryan,
The low PSI indication means the crankshaft/prop hub assembly can not hold pressure, most likely because of a leak. Since you have swapped props, it most likely is the engine side leaking.
I know of two common problems in the engine area.
1. The engine case has a drilled hole opposite the prop oil input side, usually on solid cranks to allow for better lubrication-I think. I am thinking you sent your c/s equiped engine to Barrett for OH, so that should eliminate this issue as they would not add a hole for a C/S setup.
2. The clamshell bearing around the nose part of the crankshaft is not seated properly on the alignment dowel pins allowing oil to pass it and flow back to the crankcase. Thus not allowing the nose to create the pressure needed to move the prop. This is just an assembly error that can go un-noticed in a FP set up....my hangarmate ran his engine for 600 hours like this until we converted to c/s and found the issue, like you!! The only tell tale sign, looking back was we changed several prop seals.

Barrett should help you and take care of this. I would suggest you ask them what test they want you to perform to prove to them the issue is not something you are doing.

I am happy to report that my engine/prop issue has been resolved. After ruling out any prop governor or prop issue I removed the engine and shipped it back to BPE for tear down inspection. It didn?t take long for Allen to find the problem. Divco inserted the wrong pins in the case at the front main bearing location. They inserted hollow pins instead of solid pins. The hollow pins were allowing the oil to leak back into the crankcase. Divco picked up the tab and Allen put it all back together. 5 hours flying now and all is good. Nice to back in the air again. Now I gotta finish this ATP thing...

Thanks all for the help...

Did Divco pick up the tab for your extra labor and frustration?

Divco did not cover my cost, time, labor, or frustration, and instead told me their warranty does not cover such cost. They did however cover the bill from BPE.

Glad to hear you finally got this resolved Ryan!

I'm curious why hollow pins would ever be used in this application?

miyu1975 said:

I am happy to report that my engine/prop issue has been resolved. After ruling out any prop governor or prop issue I removed the engine and shipped it back to BPE for tear down inspection. It didn?t take long for Allen to find the problem. Divco inserted the wrong pins in the case at the front main bearing location. They inserted hollow pins instead of solid pins. The hollow pins were allowing the oil to leak back into the crankcase. Divco picked up the tab and Allen put it all back together. 5 hours flying now and all is good. Nice to back in the air again. Now I gotta finish this ATP thing...

Thanks all for the help...

Click to expand...

Which pins are you referring to? My case just got back from Divco and I would like to leverage your experience to ensure they didn't make the same mistake on mine.

Larry

The pins are located where the front main bearings would sit in. In the picture you can see light shining through the hollow pins. So the oil being sent to the front main bearing section to twist the prop and control rpm was not able to hold the oil pressure due to the hollow pins. Instead, the oil was leaking back into the crankcase, according to how Allen explained it to me.

That's interesting. I thought those were the pins you were referring to. However, I think the pin on my 320 (I only remember one on the 320) were hollow and I remember thinking they must be the source of oil for that bearing and ultimately the internal nose of the crank / prop. That engine was an FP, so have no idea if maybe that was a problem.

Thanks for posting.

Larry

miyu1975 said:

The pins are located where the front main bearings would sit in. In the picture you can see light shining through the hollow pins. So the oil being sent to the front main bearing section to twist the prop and control rpm was not able to hold the oil pressure due to the hollow pins. Instead, the oil was leaking back into the crankcase, according to how Allen explained it to me.

Click to expand...

Glad to hear you got to the bottom of this. I was trying to sort a prop speed issue and talked to Allen a couple of weeks ago about running the prop leak test. He mentioned he just had this experience as an example, no details, just something about the dowel.

A little disappointing to hear a quality outfit had this happen, but good they covered it.