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Engine cutting in and out multiple times at altitude in 231


warrennn

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55 minutes ago, 81X said:

+1 million for an engine monitor- you will be surprised how much those factory gauges are off.   

Especially the gauges that weren't even installed by the factory. Like the CHT/EGT for the other five cylinders.

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Actually I have a digital fuel flow and TIT gauge (as well as digital cylinder head temp and oil temp). For nearly the entire 26 years I have owned the plane (and flown it between FL210 and 13000 on long flights) I have used a simple procedure to set power. I set the FF to about 13.3 gph and the TIT to 1520 degrees (and ~23", 2600 rpm at high altitudes and 30", 2500 rpm at low altitudes). Peak TIT is almost always 1600+.  I don't have much interest in lean of peak (one of my mechanics, who is well respected, is dead against LOP).  The previous engine lasted to 50 hours less than TBO and I have had remarkably few engine problems. I have looked into engine monitors and found them to add considerably to the workload (and also required a PC to download the data and I wasn't going to buy one just for this purpose). 

The mechanics will look at the engine in a couple of weeks. I will report back when they give their report.

Thanks very much for your suggestions.

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Warrennn

When you get a chance...

Look into engine monitors in a different way...

Look into LOP in a different way...

Look into a PC for your plane in a different way...

They are only tools... not very special or highly complex anymore...

Downloading data isn’t very hard...

Posting to the Savvy website is as easy as it gets... or some IT guy would be busy making it easier...

Having the data linked here would have us discussing the data as we see it, instead of asking a bazillion questions that are off the mark...

Times have slowly changed...

No, I’m not a young guy either.... :)

My plane got a PC to upload GPS data and download engine data... some high school kid needed a new PC, my plane got the hand me down...

Best regards,

-a-

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8 hours ago, carusoam said:

Warrennn

When you get a chance...

Look into engine monitors in a different way...

Look into LOP in a different way...

Look into a PC for your plane in a different way...

They are only tools... not very special or highly complex anymore...

Downloading data isn’t very hard...

Posting to the Savvy website is as easy as it gets... or some IT guy would be busy making it easier...

Having the data linked here would have us discussing the data as we see it, instead of asking a bazillion questions that are off the mark...

Times have slowly changed...

No, I’m not a young guy either.... :)

My plane got a PC to upload GPS data and download engine data... some high school kid needed a new PC, my plane got the hand me down...

Best regards,

-a-

+1 with these suggestions! Not to delve into the LOP/ROP wars of yesteryear but an old line mechanic who absolutely forbids LOP operations should be asked the simple question of "why". Most will sputter something about valve cooling with more fuel, blah blah blah which doesnt explain why LOP shows CHT's running cooler...not hotter...something you would instantly see with an analyzer....of course, its your engine.

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Several years ago, at 17,000 I felt my engine stutter.   It was very slight.  An engine monitor was very useful, and I could see (after a down load) the stutter I felt (which happened twice) was not my imagination.   The local mechanic couldn't find anything.   I knew I hadn't imagined anything, so I had him pull the mags and send them back to the mag shop that had inspected and repaired them about 50 hours before. They came back fixed with no charge.  :)  Apparently something had not been done properly and they were leaking at altitude.  --So, at the altitude you were flying at, mags can arc.   If nothing obvious is found on your plane and you are close to a 500 hour mag inspection, then you might want to get one done.   

Also on the topic of mags.  I was under the impression that early versions of the 231 did not have pressurized mags, but later versions did.  Most have probably been upgraded.

https://cdn2.hubspot.net/hubfs/4147179/technical_documents/service_instructions/sim20-58.pdf?t=1536939446395

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On 3/31/2019 at 9:54 PM, gsxrpilot said:

Especially the gauges that weren't even installed by the factory. Like the CHT/EGT for the other five cylinders.

Yeah, exactly.  Also contributing to this problem is that my factory CHT probe is on the coolest cylinder. 

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I haven't read all the responses so this may have been mentioned, but from the description I would look closely at the fuel tank vents.  Could have a partial blockage, or a vent was frozen over from residual moisture.  The periodic power loss can be from the tank pressure equalizing.  It would be more susceptible to symptoms of a partial blockage at altitude.  

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  • 3 weeks later...

My mechanic finally got a chance to look at the engine and found it to be in perfect health - no vacuum leaks, good compressions, good fuel pump pressure, etc. 

I am still guessing that it is water in the fuel, even though it didn't show up in the cup. For high altitude operations I need to think about isopropyl alcohol and make sure that my ADSB-in has a battery backup (so I can use the AHRS if the engine and gyros fail in IMC).

Thanks for all your advice and help!

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Warren,

Something to consider.....

On some Mooneys there is a small location of dead space lower than the drain....

When water gets in there it takes a while to get adsorbed into the fuel and exit....  molecules at a time....

It may make sense, prophylactically (?),  to use the proper water adsorbent, and procedure...

 

Some POHs May have the procedure and alcohol mentioned in the fueling section?

PP thoughts only, not a mechanic...

Best regards,

-a- 

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