Break In Procedure

Doug Rohrer · #1 02-10-2018, 04:38 AM

I will be building a Lycoming O-320 from a set of parts I am buying from various sources with the help of an A&P. My question concerns the break in procedure required. According to the Lycoming rebuild manual, proper break in consists of 75 minutes of running at various power settings using a club propeller either on an engine stand or on the airframe. This does not seem practical for a new airplane. It seems like a new engine on a new airplane will require multiple starts/stops to check for leaks, adjusting idle speed and mixture, etc. How does one go about getting good ring seal if you can't run at high power settings right from the start? What have others done? I will be using new Lycoming cylinder kits.

RV10inOz · #2 02-10-2018, 05:13 AM

Simple.

Do a start...check for leaks, fuel system and oil. Once confirmed all OK, go fly.

Do circuits, power on and off or just fly at 75% power or more for about 5-7 hours. That is it.

Now the best way to do this is......FULL RICH or even better take off, stay at say 2500AMSL and then fly at 60dF LOP. Assuming your engine will play nicely, and it likely will.

This will give better ring seal, cleaner and lower temps, plus less fuel.

Up to you, but either of the above, nothing else.

elev666 · #3 02-10-2018, 06:27 AM

After just performing the same break in on the same engine I agree with Doug all except doing any circuits , stay low @ full rich and be sure to work the engine in all aspects of your first 6 to 10 hours , IE decend with full flaps , leave the gear fairings in the hanger and fly early in the day to take advantage of cooler air since a new engine makes quite a lot more heat, I'm at 100 hrs now she only uses a quart every 8-10 hrs !

Rallylancer122 · #4 02-10-2018, 07:36 AM

Lycoming, ECI, and Superior all have Service Letters that discuss proper break in procedure for overhauled engines (which would basically be the same as your new build). I would highly recommend following them, if for no other reason than if you have a problem you can at least point to following their procedure when you try to get warranty.

I used parts from all 3 on the last engine I built, and ended up going with Superior's procedure. I had used their cylinders and reasoned they were the most expensive parts I bought, and the most critical to break in. Ran it for a couple minutes a couple of times on the ground for leak checks, set regulator, etc... and had it looked over close by an IA. Then flew. Engine broke-in in a couple hours.

If you are doing the first flight of your airplane at the same time you need to do some serious pre flight planning and scripting out of multiple scenarios.

DEM

Doug Rohrer · #5 02-10-2018, 04:14 PM

The last sentence of the last post is my major concern. I am having trouble imagining getting in a brand new airplane that has never even been taxied and blasting off for several hours at full power. What about brake testing? Checking control surfaces in the air, etc.? I am interested in how others have tackled this challenge.

Ironflight · #6 02-10-2018, 04:34 PM

Quote:

Originally Posted by Doug Rohrer

The last sentence of the last post is my major concern. I am having trouble imagining getting in a brand new airplane that has never even been taxied and blasting off for several hours at full power. What about brake testing? Checking control surfaces in the air, etc.? I am interested in how others have tackled this challenge.

You?re right - it is a significant challenge, and putting a never before run engine on a never before flown airframe is indeed notching the risk up significantly. It has been done many times, but there have been lots of issues as well. Most folks that are putting a ?new? engine on an airframe have had that engine run in on a test stand first, so much of the risk is mitigated.

The good news is that you can build a ground cooling duct fairly easily (I know there are plans drifting around - I?ve seen them) and do ground runs on the airframe without leaving the hangar. Sure, its more work when you?d rather be flying, but it is a significant risk reducer for first flight, and compared to the amount of work you?ve done getting to this point, it really is just a blip. And you can build such a duct out of hardware store materials.

It?s something to at least consider in the risk matrix.

Paul

Rallylancer122 · #7 02-10-2018, 06:51 PM

Quote:

Originally Posted by Doug Rohrer

The last sentence of the last post is my major concern. I am having trouble imagining getting in a brand new airplane that has never even been taxied and blasting off for several hours at full power. What about brake testing? Checking control surfaces in the air, etc.? I am interested in how others have tackled this challenge.

If you are using Lycoming cylinders I'd follow their instructions. In this case SI 1427C is the latest guidance on break in. In it they advocate a 15 minute ground run. They say you can do it on the plane with your flight prop as long as temps stay in limits. Subsequent they call for a normal take off, normal power climb (25 square?), and then cruise at 75% for an hour and then vary between 65 and 75% for the next hour. Then land and check it over.

So you aren't wide open for hours on end. It's pretty much normal cruise flight. (You get bored circling the airport after about 15 minutes.) If you have a CHT gauge, and you really, REALLY, should have a CHT gauge, you'll probably see your CHT's come down significantly after about 30-45 minutes. That's the rings seating. In most engines nowadays it happens quick.

As for the first flight of the plane and engine at the same time, with 10,000 RV's flying I'm sure a few thousand people have down this. EAA is also developing some serious flight test resources. Plan, plan, plan. Then practice, practice, practice. When we flight test at work (I work for an OEM), we try to think of every possible scenario and then have a plan for that. We premake flight test cards with info we want. We have people on the ground overseeing everything and directing the test. The goal is to make all the decisions ahead of time and turn the pilot into a meat servo.

You can brake test with a garden tractor and a tow bar. If a wing is heavy, suck it up for 2 hours. If the flaps won't come down it doesn't matter if you do a no flap landing after 15 minutes or 2 hours. And if you get an oil leak after ten minutes, land. It's not the end of the world As long as you don't over temp the CHT the worst that will happen is you'll glaze the cylinders, which is inconvenient but not hard to rectify.

DEM

bruceh · #8 02-10-2018, 07:32 PM

Use the search function here. There was a good post from Mahlon about the "break-in" process. I used it on my rebuilt O-320 and it worked great.

Doug Rohrer · #9 02-10-2018, 10:48 PM

Lots of good info here, especially Mahlon's article. I will look for the ground cooling rig Paul referred to. I will also investigate having the engine run in on a test stand. That would take out a lot of anxiety out of the process.

RV10inOz · #10 02-10-2018, 11:34 PM

Quote:

Originally Posted by Doug Rohrer

The last sentence of the last post is my major concern. I am having trouble imagining getting in a brand new airplane that has never even been taxied and blasting off for several hours at full power. What about brake testing? Checking control surfaces in the air, etc.? I am interested in how others have tackled this challenge.

Doug,

Do you want a manual written for you?

A first start, check leaks etc, then short taxi and brake test, first flight (15-30 min) subsequent flight, rest of test flight phase? These would all make chapters of a book/manual.

There is no need to spend lots of time on the ground at low power, all up 15-20 minutes max for first start, taxi and brake test and taxi for the first flight. There are a lot of jobs in-between so what are you really asking for here?