Breaking in a new engine

I've included the instructions below. After-the-fact we found a couple of things:
* a new Lycoming engine comes coated with oil. After the initial ground run, it was necessary to clean the plugs, as they'd fouled.
* we had to adjust the idle twice, once after the test flight and again after flying the first 15 hours. Our problem: low idle (below 1200RPM) was causing the engine to faulter. Turns out that the factory set high RPMs -- above 1700 -- and only the low idle is adjustable. I didn't know that beforehand.
* we're doing factory recommendations: 25 + 25 of mineral oil. Many people, many FBOs don't. RE: Lycoming recommendations of changing oil 5 hours after going to muligrade or straight weight oil, virtually no one does that.
* Lycoming recommendations call for re-calibration of oil temp and CHT temp gauges at engine change. Again, few FBOs do it. This one we'd recommend, as we're seeing very low oil temps.

I didn't understand how differently the plane would perform after the overhaul, but it does. Good luck with it.

I'd also recommend reading John Frank's piece on the Web (he's exec director of Cessna Pilots Association) at: http://www.avweb.com/news/maint/182895-1.html

Best regards,

Andy Czernek
N201XG 1978 M20J
Mukilteo, WA -- KPAE

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In addition to running the engine and checking for CO during climb and in cruise (and addressing any seal gaps that may be in the firewall or the belly), the following are Jim Ryan's (jryan@sequent.com) list for break-in.

Jim used this in the break-in of an O-360 engine with constant speed prop. These lists were written for his purposes. Different engines and cylinder types use different procedures. 25 square means 2500, 25 inches manifold press; you may need specific instructions if you have a fixed pitch prop. Chrome cylinders may have a different initial procedure.

Jim's comments: . "It's not a routine event and I was a little nervous, especially when there was some roughness about an hour into the flight. It went away and didn't recur, but how it left me feeling is the reason to have this at hand!"

Lycoming Checklist:

Overall Purpose, Application and Warnings:

* Objective: seat piston rings and stabilize oil consumption
* Applies to top or complete overhaul
* In general avoid excessive ground runs to prevent overheating. Run long enough to ensure essential systems are functioning normally.
* Lycoming provides a formula for engine oil consumption. According to that, expect consumption of .6 quarts per hour maximum

Ground Test

* Watch CHT carefully
* Pre-oil engine per latest edition of the Service Instruction
1241 - means mineral oil?
* Face into the wind.
* Idle at 1,000 RPM until oil temperature stabilizes or reaches 140 degrees Fahrenheit; oil pressure must not be less than that specified in the POH.
* Do a mag check.
* Continue operation 1,000 - 1,200 RPM for 15 minutes. Watch CHT, oil temperature and oil pressure - all must remain within limits.
* Shut down and allow the engine to cool.
* Start the engine again and monitor oil pressure. Run at 1,500 RPM for 5 minutes and cycle the prop.
* Run the engine at full static speed no more than 10 seconds - How long is ideal?
* After full power run, allow the engine to cool moderately and shut down using the idle mixture.
* Check oil filter or screen for contamination.

Flight Test

* Perform normal pre-flight run-up.
* Take off using standard power
* As soon as possible reduce to climb power and use a shallow climb angle (cruise climb?)
* At cruise altitude, reduce power to 75% for the first hour (what should the leaning be?). For the second hour alternate power between 65% and 75% power
* How often?
* Just those two settings or other intermediate?
* Recommend 5,000 density altitude to allow sufficient cruise power for a good break-in.
* (Note: determine what constitutes 65% and 75% at a target altitude, say 4,500 - 5,500 feet).
* Increase power to maximum for the next 30 minutes (what should RPMs be?)
* Avoid low manifold pressure (less than 15 inches) during high RPMs
* Avoid rapid changes in RPMs if dynamic counterweights are in use.
* Descend at low cruise power while closely watching engine instruments
* Avoid long descents at low manifold pressure
* Avoid closed throttle descents - causes ring flutter
* Do not reduce altitude rapidly or engine temperature may drop too quickly
* After landing and shut-down, check for fuel and oil consumption vs. POH and check for leaks.
* Check oil screen or filter for contamination.
* To seat the rings in a newly overhauled engine, cruise at 65% to 75% power for the first 50 hours or until engine oil stabilizes.
* Does this apply to a new or fully overhauled engine only?
* Use mineral oil all during this time?

Jim Ryan's complete list:

Flight Test
* Perform normal pre-flight run-up as quickly as possible. Ensure normal oil pressure and temperature off the peg
* Take off using full power
* As quickly as possible reduce to climb power (25 squared) and use a shallow climb angle, 200-300 FPM
* Keep mixture rich at all times to promote cooling
* First Hour: at cruise altitude, reduce power to 75%
* Second hour: alternate power 65% -- 75% power
* Next 30 minutes: Increase power to climb power (25 squared)
* Descend at low cruise power while closely watching engine instruments
* Avoid long descents at low manifold pressure
* Avoid closed throttle descents - causes ring flutter
* Do not reduce altitude rapidly or engine temperature may drop too quickly
* After landing and shut-down, check for fuel and oil consumption vs. POH and check for leaks.
* Check oil screen or filter for contamination.

Notes:
* Stay at 5,000 density altitude or less to allow sufficient cruise power for a good break-in.
* To seat the rings in a newly overhauled engine, cruise at 65% to 75% power for the first 25 hours or until engine oil stabilizes, which should be as soon as 10 hours
* Change back to conventional oil after 25 hours; sooner if it's clear the rings have seated
* Avoid low manifold pressure (less than 15 inches) during high RPMs
* Avoid rapid changes in RPMs if dynamic counterweights are in use

Note that dynamic counterweights are used in Lycoming IO-360's.

Revision: 10/28/2010