In need of a mechanic in Pennsylvania (KDUJ)

[highlowfastslow]

Hey guys - I thought I would put this out there to see if anyone has any ideas or knows any A&Ps in central PA. 

I was traveling from Chicago to Cape Cod today, a regular trip, but started getting some vibration at the start of my second leg when I left Clarion County, PA. The plane was generating good power and got to 7,000 just fine, but kept having brief changes in power and RPMs. It was enough that i didn't want to continue and so I started looking at Foreflight for places to land with a mechanic. Dubois (KDUJ) showed up as having maintenance, and we happened to literally be right over it, so I landed, but turns out there are no longer any active mechanics here. 

I was able to get a mechanic to drive down from St. Mary's. Capable guy and, from talking to the owner and someone that knows him, a very capable shop. He took a look at my cylinders - cylinders 1-3 had good compression readings. Cylinder 4 had good readings except for at top-dead-center it was losing pressure and you could hear the air escaping. The mechanic took this to mean it's likely that the rings are bad, but to be sure the cylinder has to be pulled. I did another run up after the compression readings and, while within RPM drop limits, rougher than normal. 

Here is the problem - the St. Mary's mechanic won't pull the cylinder at the field i'm currently at and would like me to fly it there. It's only a 10-15 minute flight, but i'm hesitant to take it up at this point. My questions are:

- Does anyone know of a mechanic capable of pulling a cylinder that would be able to do it at KDUJ (they have a hangar we can use)?

- Does the mechanics view that the ring is bad make sense given the compression reading is only low at TDC?

Some other observations that might help the diagnosis:

- I went through 1.5-2 quarts on only a 2 hour leg from Chicago, so clearly oil is being burned. There were no leaks to be found. 

- It did not want to run at peak or LOP and started running rough before all cylinders peaked in cruise

- It's idling at 500 RPM and is rough at idle. It usually idles around 7-800 and idles just fine

- When landing there were certain low power settings with more pronounced vibration (1500-1700 RPMs)

Any ideas that MS has would be appreciated!

Edit: Should also note that the #4 plug had oil on it, the other 3 did not. 

 

Edited August 5, 2017 by highlowfastslow

[Andy95W]

1.) how low was #4?

2.) where was the air escaping- oil filler tube, exhaust, or air intake?

Regardless, you'll probably need an overhauled cylinder (or get yours overhauled if you want to save money and have the extra time.)

[DVA]

Any ideas that MS has would be appreciated!
 

Hi,

If you'd like to chat we're in Allentown which is about 100 east but on your way. At the least I can help you research options. My cell is (484) 239-0007.

Dave

[highlowfastslow]

6 minutes ago, Andy95W said:

1.) how low was #4?

2.) where was the air escaping- oil filler tube, exhaust, or air intake?

Regardless, you'll probably need an overhauled cylinder (or get yours overhauled if you want to save money and have the extra time.)

1) I'm not sure, should have asked

2) It was coming out of the filler tube

Are you saying overhaul makes more sense than replacing the rings? Will it just happen again if they're replaced? 

The cylinders were all overhauled in 2010

[Andy95W]

Yes, you're right, a full cylinder overhaul would not be required.  New rings and re-hone the barrel, and IRAN (Inspect and Repair As Necessary) the rest.  

[Garryowen]

Do you have an engine monitor and can you access the data from where you are by chance? That might have some tell tale signs of what's really going on. Might be as simple as a clogged fuel injector or a failing plug. I know that doesn't explain the oil burn, but I get nervous when the first step is to pull a cylinder in the field. 

[takair]

Hmm.  It sounds like the cylinder may need work, but I'm not sure that would lead to sudden roughness.  Would be helpful if you could get the compression value.  Beyond that, do you have an analyzer and can you tell us what it was doing?  Sudden roughness tends to be plugs, injectors, magnetos and valves.  Did you do mag check?  Maybe I missed that above.  What else did the mechanic check?  Injectors? Plugs?  If one of those is causing roughness it may get you to another airport to do more significant work.  You could have an oil fouled plug from the low compression.  Borescope would help and might be easier at the location than full cylinder removal.  Not suggesting flying without understanding what is going on, but understanding what is going on may allow you to move the plane.

[Andy95W]

21 minutes ago, Garryowen said:

Might be as simple as a clogged fuel injector or a failing plug. I know that doesn't explain the oil burn, but I get nervous when the first step is to pull a cylinder in the field. 

I think this is excellent advice.  Fairly easy to accomplish and then test run BEFORE pulling the cylinder.

[highlowfastslow]

Mooneyspace is awesome. This is great advice and I spoke with Dave earlier, who was extremely helpful.

I do have an engine monitor but I'm not sure I'll be able to pull it here. The CHTs and EGTs were all normal during the flight, but will see if I can get them pulled.

I'm going to try and get a compression value from the mechanic tomorrow. He also did a borescope and said things "looked good", but want to confirm with him what he saw. I wish I knew the right questions to ask on the spot, it's a learning process.

He did check the plugs and #4 was pretty oily and probably fouled during flight. It sounds like that could be leading to the roughness?

I did do a mag check and the RPMs were within limits, but it felt slightly rougher than normal. He didn't check the injectors; once he saw the readings on #4 he stopped going further.

I'm going to confirm with him tomorrow that he got a look at the valve and it looked ok.

The clear piece of feedback here is don't rush to pull the cylinder...will be sure to heed that advice and exhaust other options first. Thanks all.


Sent from my iPhone using Tapatalk

[Yetti]

He did check the plugs and #4 was pretty oily and probably fouled during flight. It sounds like that could be leading to the roughness?  How many hours on #4?   Clean plugs to start with, that should clear up the roughness. If it does not then you might have a stuck valve.  Just ream the valve guide. You can poor man a compression test by pulling the prop through and see what cylinders are soft.   If you are sticking a valve, I think that is was causes cams to fail and start the spalling process.

[takair]

7 hours ago, highlowfastslow said:

Mooneyspace is awesome. This is great advice and I spoke with Dave earlier, who was extremely helpful.

I do have an engine monitor but I'm not sure I'll be able to pull it here. The CHTs and EGTs were all normal during the flight, but will see if I can get them pulled.

I'm going to try and get a compression value from the mechanic tomorrow. He also did a borescope and said things "looked good", but want to confirm with him what he saw. I wish I knew the right questions to ask on the spot, it's a learning process.

He did check the plugs and #4 was pretty oily and probably fouled during flight. It sounds like that could be leading to the roughness?

I did do a mag check and the RPMs were within limits, but it felt slightly rougher than normal. He didn't check the injectors; once he saw the readings on #4 he stopped going further.

I'm going to confirm with him tomorrow that he got a look at the valve and it looked ok.

The clear piece of feedback here is don't rush to pull the cylinder...will be sure to heed that advice and exhaust other options first. Thanks all.


Sent from my iPhone using Tapatalk

It is very possible that the oil fouled plug caused roughness.  Did the mechanic who looked at the aircraft suggest this as well?  Perhaps this comes down to the compression reading.  If within limits and not going out the exhaust valve, then I suspect that the mechanic is saying it is safe for the short flight to his facility.  The oil fouling willl likely return eventually, but typically only affects one plug at the beginning.  For a short flight, it may be safe by clearing the plug, good mag check, and monitoring CHT.  No PAX, have a plan if things get worse.  Ultimately, we are not there, so you need to rely to some degree on the mechanic.  Ask him straight up if it is safe and legal for the short flight to his facility.  I can appreciate why he wants it there.  While it is not a terribly difficult job, It can get expensive paying for his travel if simple tools are not on hand or forgotten....you may be down longer as well.

[BradB]

Sorry, I am out of town this weekend, so can't be of much help.

 

but KJHW is a Mooney service center and not that far from you.  They take good care of my plane if you want to give them a call.  

716-665-4800

 

sorry to hear about the trouble.  

 

Brad

[highlowfastslow]

5 hours ago, Yetti said:

He did check the plugs and #4 was pretty oily and probably fouled during flight. It sounds like that could be leading to the roughness?  How many hours on #4?   Clean plugs to start with, that should clear up the roughness. If it does not then you might have a stuck valve.  Just ream the valve guide. You can poor man a compression test by pulling the prop through and see what cylinders are soft.   If you are sticking a valve, I think that is was causes cams to fail and start the spalling process.

I'm not sure how many hours on the plug. The cylinder has about 235 hours it looks like. Cleaning of the plugs did help so that seems like the problem and what's leading to roughness. Now we just need to find out what's causing it...

4 hours ago, takair said:

It is very possible that the oil fouled plug caused roughness.  Did the mechanic who looked at the aircraft suggest this as well?  Perhaps this comes down to the compression reading.  If within limits and not going out the exhaust valve, then I suspect that the mechanic is saying it is safe for the short flight to his facility.  The oil fouling willl likely return eventually, but typically only affects one plug at the beginning.  For a short flight, it may be safe by clearing the plug, good mag check, and monitoring CHT.  No PAX, have a plan if things get worse.  Ultimately, we are not there, so you need to rely to some degree on the mechanic.  Ask him straight up if it is safe and legal for the short flight to his facility.  I can appreciate why he wants it there.  While it is not a terribly difficult job, It can get expensive paying for his travel if simple tools are not on hand or forgotten....you may be down longer as well.

Yes, the mechanic did suggest the fouled plug on #4 was causing the roughness. He cleaned the plugs and that did help significantly. 

The update is that i'm now in Queen City, PA and going to meet with Dave this afternoon. After doing several run ups and a full power run down the runway this morning, I decided it was safe to depart. It made 2700 rpm and readings were normal taking off and climbing. 

Kept a really close eye on #4 the whole flight. The roughness did return after a while and it manifested itself in a slight drop (20 degrees or so) with #4 EGT, but it then came back and roughness disappeared. Roughness would last no more than 3-4 seconds at a time. This happened every 5-10 minutes or so. On the hour long flight it went through another 3/4 of a quart so still burning a lot of oil. CHTs held steady at 270 the entire way and oil temps and pressure steady as well. 

Feel good about making the flight and optimistic that i can get the right answers here at Queen City. 

Thanks again for all the help everyone. Will update once we get some answers. 

[highlowfastslow]

1 hour ago, BradB said:

Sorry, I am out of town this weekend, so can't be of much help.

 

but KJHW is a Mooney service center and not that far from you.  They take good care of my plane if you want to give them a call.  

716-665-4800

 

sorry to hear about the trouble.  

 

Brad

No worries Brad and thanks for the suggestion. I'm at KXLL now and will be getting a second opinion this afternoon. Feel good that whatever the cause can get taken care of here. 

[Yetti]

You might be able to switch to a Champion REM 37BY .  It has a longer electrode to keep from oil fouling.   https://www.lycoming.com/sites/default/files/SI1042AC Approved Spark Plugs.pdf

 

[orionflt]

did you guys make it home ok?

Brian

[bradp]

Did you go visit DVA?  One thing you can try is to fill the cylinder with MMO, push the prop to TDC for that cyl to hydro-lock the MMO, and let it sit overnight.  It may help unstuck an intact piston ring .  The fact that the symptoms come and go may be a combination of oil fouling and ... my bet...  is you have a broken ring.  Just a hunch.  

[highlowfastslow]

4 hours ago, orionflt said:

did you guys make it home ok?

Brian

We did! Great meeting you Brian - thank you for the offer to help us out and for taking a look at the cylinder.

It took us a while to realize it was an option, but we ended up renting a car and driving to New Hampshire. Easy 6 hour drive then we'll head back to Chicago Tuesday. We'll be back sometime during the weekend of Aug 19th to pick up the plane so if you're around we'll see you then. Thanks again. 

2 hours ago, bradp said:

Did you go visit DVA?  One thing you can try is to fill the cylinder with MMO, push the prop to TDC for that cyl to hydro-lock the MMO, and let it sit overnight.  It may help unstuck an intact piston ring .  The fact that the symptoms come and go may be a combination of oil fouling and ... my bet...  is you have a broken ring.  Just a hunch.  

We did. Dave was extremely helpful and and generous with his time on Saturday. Brian above also happened to be there and helped us out. 

You're probably spot on with your hunch. We boresxoped number 4 and saw a couple things:

- a lot of oil

- significant scoring on the wall of the cylinder

The cylinder will have to be pulled and I'll have to get a new one based on how bad the scoring is. We're thinking one of the rings cracked, likely the oil control ring?

What typically causes a ring to crack? Just age or are there other drivers? I assume it was replaced when the cylinders were all overhauled in 2010, but not positive  

Unfortunately I caught it too late to save the cylinder. Lesson learned, although I'm not sure how to spot that problem sooner. I never saw abnormal temperatures and the plug didn't start fouling until this last flight. 

Will cost me a couple of AMUs, but should have it back in the air in a couple weeks so all is good. 

[jetdriven]

3 hours ago, bradp said:

Did you go visit DVA?  One thing you can try is to fill the cylinder with MMO, push the prop to TDC for that cyl to hydro-lock the MMO, and let it sit overnight.  It may help unstuck an intact piston ring .  The fact that the symptoms come and go may be a combination of oil fouling and ... my bet...  is you have a broken ring.  Just a hunch.  

I've done that in the past but there's a better chemical to use, Berryman' B12 Chemtool. Not the "Chem-dip" from the gallon paint can (that's water base soap), but B12 Chemtool from the quest can or a square gallon. This stuff actually will dissolve the carbon and freee up rings with the procedure you describe. 

[Andy95W]

Highlow- thanks for the follow up.  Hope you let us know the final outcome.

[carusoam]

Great report, highLow!

Best regards,

-a-

[highlowfastslow]

While I'm waiting on a new cylinder to get put in, I thought I'd ask about the best procedure when breaking in one new cylinder. I did some searching and couldn't find consensus when just replacing one cylinder. Should I use mineral oil and run it like I'm breaking in a new engine? Or do I use AD oil and run it normally? I obviously don't want to put my other 3 cylinders at risk when breaking in the new cylinder. 

[Marauder]

4 minutes ago, highlowfastslow said:

While I'm waiting on a new cylinder to get put in, I thought I'd ask about the best procedure when breaking in one new cylinder. I did some searching and couldn't find consensus when just replacing one cylinder. Should I use mineral oil and run it like I'm breaking in a new engine? Or do I use AD oil and run it normally? I obviously don't want to put my other 3 cylinders at risk when breaking in the new cylinder. 

I will let the experts chime in but I was taught to switch to mineral oil and break in like I was breaking in all new cylinders. You definitely want the rings to seat and I don't think you can do that with AD oil. 

[DVA]

Truls, for non turbo engines always run mineral oil and fly it hard. The #1 reason for a poor or in incomplete break-in is babying the engine during the first 10-25 hours.

[DVA]

You definitely want the rings to seat and I don't think you can do that with AD oil. 

Actually AD oil will work too, albeit slower when compared to MO. Lycoming wants all turbo engines to to break in with AD to favor the proper lubricating properties needed for the turbo.