new engine break in procedure

well after months of waiting after a crankshaft failure last august my 185 finally has its heart and lung transplant finished. i upgraded to a factory new IO-550 and a mccauley 3 blade prop. it was supposed to be available this last weekend but the fog thwarted me from getting to fly it. my mechanic wants to do the first flight both to double check that everything is operating OK and to start the break in process. after that his only advice was to go fly and probably avoid a lot of touch and goes for awhile. looking around the interweb it seems there are a lot of theories on how best to break in an engine. there doesnt seem to be much agreement on how long until the cylinders are "broken in". i've seen estimates of 50 hrs total down to "10 hrs after oil consumption stabilizes". it seems i should expect high oil consumption initially but no one says how much is to be expected and how much might be too much. there is also no agreement on which oil to use. i was flying my IO520 LOP and some sources say LOP is to be avoided during break in and some say not to worry. those of you who have been through this, how did you manage this process and how did it turn out? any definite no-nos that resulted in pulling cylinders early? hopefullly i will finally get off the ground next weekend.

One run up to check for leaks... PUSH the airplane to the apron/taxi-way and then fire it up.. take off and balls to the wall (then 75 to 80% power and above & keep the prop loaded) for 2 hours. DO NOT come back unless you have a damn good reason to do so. Any low power settings or early return will = glazed cylinders and they'll never seat. I usually see temps drop around 1 hr -45 minutes and I know the rings have found their "grove" !

Continental SB M89-7R1 is Continental's take on it.

John Scott

If your mechanic was the one that built the eng then do what he says. If not, the shop had a procedure. Your mechanic should tell you what they recomend if not call them.

longwinglover and stewartb-thanks for the links. i already had the TCM SB but it seemed to me that it only covered the run in which is done at the factory and the first flight or test flight which is being done by my mechanic. i dont get my mitts on it until these have already been done. my admittedly weak understanding of the process is that the break in consists of the first flight and then some indeterminate number of hours after that. i was seeking some additional advice on that last portion of the process which is the only part i am doing myself and those first few hours after the test flight is where things seem to be dealers choice. from what i have read most of the ring seating has occurred after the run in and the first flight so maybe that is why TCM doesnt specify how to operate the engine after that.
stewartb- yep that is the prop i upgraded to. i was going to go with the MT composite prop but my mechanic talked me out of it. he says he takes care of some other 185s with the MT prop and he has had to replace multiple starters on those planes. the plane was already nose heavy when flown alone and with hydraulic wheel skies. i guess i will run out of nose up trim even sooner now unless i put something heavy in the extended baggage.

High manifold pressures to seat the rings and lower altitudes, 3500 ft or below.Low CHT temps by not doing steep climbs. No touch and gos. Fly for an hour or so and check for leaks and repeat. When oil consumption stabilizers the cylinders are broken in, probably 10 hrs. or less.

I for one would not want someone else breaking in an engine for me. I've broken in several TCM engines, and it's not rocket science, but I like to know how my engines have been treated.

First of all, find a power chart for that engine. The IO-550 is a VERY different engine than the IO-520. RPM/MP settings that would be normal in an IO-520 will be a LOT of power in a 550, and depending on the model of 550, TCM says NO leaning of the mixture at power settings greater than 70% or so, again, depending on the model of engine. Run that thing at the RPM/MP settings many folks use in a 520, lean the engine and you WILL be replacing cylinders. Run it according to TCM guidance, and it'll go to TBO without changing a cylinder.

I would not run LOP till the engine is broken in. I've received that advice from several. It may not really be necessary, but I can't imagine it hurting anything to run ROP at first. I ran 550's LOP for many hundreds of hours, and loved the way they run. READ the power charts, though.

Great engine, LOTS of torque. If you fly floats, you will LOVE that engine.

As to continued break in, just follow TCM guidance. Change power settings periodically, run fairly high power settings at least until CHT's start coming down, which they should in the first few hours of operation. This is another reason I would want to do ALL the break in flying--to track CHANGES. This is how you determine if it's breaking in properly.

I agree with Stewart--dump the oil at 10 to 12 hours, cut the filter, fresh oil and filter, and run it to 25 hours, change it again. Then every 50 hours oil change. Follow Steve's routine as well.

Great engine and prop. You'll love it, BUT--be sure to read the the power charts for THAT ENGINE, and abide by them.

If you want good advice on TCM engines, call TCM and ask to talk to Loren Lemen. He is a REAL expert on their engines, and is their head tech rep. Or at least he was.

MTV

well after weeks of waiting out the weather and the usual conflicts with everyday life i finally got to fly the thing this weekend. i went up with my mechanic and we went over differences from the IO-520 and we took down some data on egt/chts. as far as performance with only one take off and with it being winter and with just two people on board and since i havent flown wheels since last may i cant really comment.(after spending all that money it sure "seemed" better) in the air it was bumpy on sunday but it sure seemed like a lot less vibration with the three blade prop and even at the higher rpms it sounded quieter. the IO-550 has tcm "tuned induction" fuel injection nozzles which are supposed to be like GAMI-jectors but it appears one cylinder peaks out at a significantly different fuel flow. the other five seem to be more consistent. we may change that one injector if this trend continues. the chts seemed to have a normal distribution. with landing it was evident that the plane is much more nose heavy than before. i have hydraulic wheel skis on right now as well and with those and the three blade prop i ran out of nose up trim much earlier than i'm used to. being nose heavy does make wheel landing easier though. i think i wont really know about take off performance until i take off with a big load or in deep snow. what i'm really looking forward to is next float season, thats the reason i did all this. all in all i'm happy to just be flying again, this four month hiatus is the longest i have gone without flying since i got my private fifteen years ago.

You might want to calculate a weight and balance, skis up and skis down, and verify that with one or two people in the front seats and with skis you are within the forward limit.

MTV