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Engine Break in Procedures
Gjunkie1
#1 Posted : Tuesday, June 07, 2011 1:23:07 PM(UTC)
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Provided by Herman Dierks:

One thing I like to do is to drain the oil after the first hour or first flight.
There is a lot of small metal that comes off the cylinders
that were freshly honed.
I don't like letting that oil circulate around in the engine as that metal
will become embedded in the soft bearings and start wearing hard surfaces (crank
etc).
If you have a spin-on oil filter, this is less critical, but I still do it
anyway.
If you have oil screen, I would certainly do it as the screen does not
catch these fine particals. This costs you maybe 8 quarts of oil, but I think
its worth it.

Another source of info is on the ECI web site:
http://www.eci.aero/pdf/...de=bookmarks&page=9


Steve Johnson
MX2
Nashville, TN
Gjunkie1
#2 Posted : Tuesday, June 07, 2011 2:49:24 PM(UTC)
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From Andrew Boyd

> How often do you reduce the RPM by 100?

Every few minutes. Let's say I take off at 2700 RPM,
redline with the prop control full forward. Won't hurt
the engine in the least! Main thing you have to worry
about high RPM (past the redline) is the prop.

Anyways, leave the throttle wide open, and the mixture
full rich for the entire flight.

A few minutes after I level off at 1500 feet, RPM back
to 2600. A few minutes later, prop back to 2500. A few
minutes later, prop back to 2400. Then back to 2500.
Then back to 2600. Then back to 2700. Then rinse,
lather, repeat, as it says on the shampoo bottle. That's
what I do, anyways, and my engines have the best
compressions on the field.

> How do you keep the CHT below 400?

Kind of a trick question. Keep the nose down in the climb
to keep lots of air going through the engine. Cowl flaps all
the way open. Mixture full rich - check the fuel flow in GPH
on the totalizer to make sure it's the right number, which is
your horsepower divided by 10. If you have 260 hp, you
should be flowing 26 gph. 200hp, 20 gph. See BSFC.

If your mechanical fuel gph reads significantly higher than
your fuel totalizer, check for a plugged injector. I have an
ultrasonic cleaner for them.

If your CHTs are consistently over 400 (after break-in), time
to look at your baffles and seals to make sure that the air is
being forced past the cylinders. This is often the cause.

If your oil temp is too high, make sure that the oil cooler
is not externally plugged up with junk - and did you flush it
internally when the engine was out? Also, check the
vernatherm for correct operation. Make sure it's allowing
the oil to cycle through the cooler.

Oil temp is normally high during break-in, because the
hot gases are blowing past the rings into the crankcase,
heating up the oil. The rings haven't seated, after all.

Flying an engine frequently is the key to a strong, healthy,
long-lasting engine. I don't like to let an engine sit for more
than 2 weeks, otherwise it will corrode internally. If you live
someplace humid and salty, you're going to need to run it
more often than every 2 weeks!

Hope this helps! My apologies to the old pros here who
have heard all this all a million times before. This is really
aimed at the newbies on the list, who didn't grow up with
(aircraft) engines.

--
www.pittspecials.com

Steve Johnson
MX2
Nashville, TN
Gjunkie1
#3 Posted : Tuesday, June 07, 2011 2:50:25 PM(UTC)
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From Chris Porter

I've done the break in flights in many 172's. Andy was pretty spot on. I
do just a few things different. Everything was taken straight from the
Lycoming recommended procedure:
http://www.lycoming.text...service-instructions/pd
fs/SI1427B.pdf

Minimize ground time, like Andy said.
Climb out at a shallow angle/higher airspeed
At cruise altitude, set power to 75% for the first hour.
Second hour: alternate between 65% and 75% power every ten minutes.
Descent to the airport is gradual, not pulling off more than 1 inch of MP
per minute.

We use mineral oil for the first 50 hours of operation. The oil is changed
after the break-in flight, after 25 hours of operation, and 50 hours of
operation.

For those first 50 hours of flying we try to maximize cross country flying
and limit air work especially anything involved low airspeed, high power
settings like a power on stall. Definitely no pattern work.




Chris Porter
Manager, CFI
Horizon Aviation

Steve Johnson
MX2
Nashville, TN
Gjunkie1
#4 Posted : Tuesday, June 07, 2011 2:51:56 PM(UTC)
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From Andrew Boyd

>>Anytime I replace an engine (or a jug), I put mineral
>>oil in it, and run it for a minute with the cowls off to
>>make sure I don't have any leaks, etc. Fill it with gas.
>>
>>Cowls go on. Taxi out to runway with minimum delay,
>>check the mags. As soon as the CHT is in the green
>>(for cyl-piston clearance) all the knobs in, take off with
>>minimum delay.
>>
>>Orbit the airport at 1500 AGL with all the knobs in. Don't
>>leave gliding distance of the airport. Don't climb too high,
>>because your manifold pressure will drop off (bad), and if
>>you have a fire, you want to get it on the ground NOW.
>>
>>Breaking an engine in, is all about seating the rings. If you
>>have a new or overhauled engine, it probably has been run
>>already (check for a sheet). If you're just changing a jug
>>with new rings, this is not the case.
>>
>>You want maximum cylinder pressure, pushing the rings out
>>against the cylinder wall. Try to keep the CHT below 400F
>>if you can. I don't like them higher than that, but redline is
>>probably 450F for you.
>>
>>I leave the throttle and mixture all the way in, and I vary the
>>prop 100 RPM every now and then. By backing the RPM off
>>and leaving the throttle WOT, you can get the cylinder pressure
>>up, which is good. You will not detonate or pre-ignite with
>>100LL as long as you don't oversquare more than 5 MP
>>vs RPM (eg with 29 inches MP, minimum 2400 RPM).
>>
>>Watch the oil temp. When it drops suddenly, the rings have
>>seated, because the hot gases are no longer blowing past
>>the rings into the crankcase. You can actually instrument
>>the crankcase with a manometer and watch each cylinder
>>seat individually as the pressure drops, if you're a gearhead.
>>
>>Minimize taxiing. No touch & goes. Keep the throttle in
>>for max pressure, and the mixture in for max cooling. First
>>flight should be as long as you can stand it, or until you run
>>out of gas. At least an hour. Two hours is better. If you
>>do this, when you are done you will have seated the rings.
>>
>>As long as you keep the CHT under control, the harder
>>you run it, the better an engine you will have.
>>
>>--
>>www.pittspecials.com
Steve Johnson
MX2
Nashville, TN
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