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Breaking in IO550N?


Amelia

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Pieces and parts are arriving for my field-overhaul M20S engine. Might be able to fly it in the next few weeks!! What do I need to know about how best to run it? I know to fly it hard the first ten hours, but then? How will this one differ from the IO550G I wore out? I’d appreciate specifics so much. Will it like LOP? 

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People much more knowledgeable than me can comment, but the break-in procedure is normally dependent on the types of cylinders you're installing.  OEM cylinders take a lot more work than nickel, etc.

You're basically looking for all of the temperatures to stabilize.  Aiui this happens much faster for nickel than OEM -- but I've only done a couple of these and I'm far from an expert.

 

ETA:  Went looking for this article from Mike Busch.  Thought was a pretty nice, quick overview:

https://resources.savvyaviation.com/wp-content/uploads/articles_aopa/AOPA_2019-01_breaking-good.pdf

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1 hour ago, Amelia said:

Pieces and parts are arriving for my field-overhaul M20S engine. Might be able to fly it in the next few weeks!! What do I need to know about how best to run it? I know to fly it hard the first ten hours, but then? How will this one differ from the IO550G I wore out? I’d appreciate specifics so much. Will it like LOP? 

Do not run LOP. You will be running 75% power and your CHTs will be hot as rings are trying to seat. LOP will not create the pressures you need to seat the rings and at 75% power you risk detonation. Run ROP and keep a close eye on CHTs. Do not be afraid to feed it fuel if it runs hot. Most engines will give you a distinct notice they have seated in when CHTs drop while making no changes to the power or mixture. After 50 hours and a confirmed seating then I would entertain LOP operations.

 

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18 hours ago, M20Doc said:

This might help, from Continental.  I’d break it in using the method prescribed by the person who will be providing warranty.

https://www.continental.aero/xPublications/xService Bulletins/Experimental PMA/SIL012/

 

17 hours ago, GeeBee said:

Do not run LOP. You will be running 75% power and your CHTs will be hot as rings are trying to seat. LOP will not create the pressures you need to seat the rings and at 75% power you risk detonation. Run ROP and keep a close eye on CHTs. Do not be afraid to feed it fuel if it runs hot. Most engines will give you a distinct notice they have seated in when CHTs drop while making no changes to the power or mixture. After 50 hours and a confirmed seating then I would entertain LOP operations.

 

For @Amelia - These posts  ^ ^ ^ ^

Follow the Continental instructions TO THE LETTER.  Ask me how I know.

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Everyone stresses over this because there is a lot of money involved and, like leaning, it's fodder for a multitude of magazine articles that make it sound complicated.

Nitrided cylinders break in pretty quickly and about the only two ways you can screw them up is to overheat them (just watch the CHTs) and run for extended periods at low power (less than 65%). I have been associated with a number of flight schools that go through engines frequently because of high utilization and they all just test fly a new engine for an hour or two and turn it loose on the line with a placard saying to use mineral oil, keep the power up and don't do touch and goes. After the first 24-50 hours, they would switch to AD oil. I cannot recall any ever having a problem. 

If you get an engine overhauled by the factory or one of the large shops, it will have been run in for a couple of hours in a test cell and it will be 90% broken in when you uncrate it. If you get a field overhaul that has not been run in, then you need to follow the instructions carefully for the first flight. 

The most important thing is to preserve your warranty. If you have an engine problem, it will most likely be due to something done (or not done) by the overhauler -- not you. The overhauler may naturally look for a way to shift blame and expense. You don't want to give them an easy out by not following their break in procedure.

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Thank you, thank you each for this valuable guidance. I’ve read every word, will reread it all several times before Fly-day…whenever that turns out to be! The IA threatens to ride along at least the first hour, maybe more, with me to make sure he is happy with what the engine monitor is telling us. Then he advises several more high power hours also within gliding distance of home. This will be a nice time of year to do that. Again, I’m most appreciative that you took the time to explain and find references.

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On 3/19/2023 at 10:40 AM, jetdriven said:

I think continental allows for ashless dispersant  oil. Just get the permission of the person who overhauled it and he's going to warranty it. 

Not sure that’s correct:

IV. BREAK-IN PROCEDURES
We recommend these procedures to break-in a new, overhauled, or repaired engine:
NOTE: The following break-in procedures apply for through-hardened steel and Nickel+CarbideTM cylinder bores.
NOTE: Use 50-weight, aviation grade mineral oil for engine break-in.
 

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9 minutes ago, M20Doc said:

Not sure that’s correct:

IV. BREAK-IN PROCEDURES
We recommend these procedures to break-in a new, overhauled, or repaired engine:
NOTE: The following break-in procedures apply for through-hardened steel and Nickel+CarbideTM cylinder bores.
NOTE: Use 50-weight, aviation grade mineral oil for engine break-in.
 

https://phillips66lubricants.com/product/type-m-aviation-oil/

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