Whee, this is still fresh in my mind, having done my 1st flight last November.
I also had to deal with a freshly OH engine, bolt-on to a untested air frame…In my case, I did stay within reach of the airfield for flight 1 to 4. Made arrangement with the controller prior to the 1[SUP]st[/SUP] flight and the game plan was to circle the airfield at 1000ft above circuit altitude.
I’ve run my engine harder than what you’ve suggested. I’ve read a lot about that, and there is a lot of different approaches suggested by different eng mfg. In my case, I ran the engine between 75 % to 100 % for the 1[SUP]st[/SUP] hour, cycling from one setting to another every 5 minutes or so. Everyone agreed that CHT should be kept as low as practical. In my case, OAT was below freezing level, so my CHT never exceeded 380.
One critical thing that you haven’t mentioned in your post is: Ground runs prior to 1[SUP]st[/SUP] flight.
I suggest to read an extract from Russel Mahlon on that subject. He also suggest a run-in schedule prior to the 1[SUP]st[/SUP] flight. The take away form that is never exceed 350F CHT during any ground operation. Lack of cooling on the ground will glaze the cylinder walls and prevent actual break in from occurring during you actual flight runs. In my case, I’ve limited my CHT on the ground to 320 F.
One observation as well about Brake Break-in…It took me 3 ground runs (following the brake mfg break-in procedure) in order to achieve reasonable braking action. So plan for some level of ground runs prior to the 1stflight.
Good luck
Mike
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Hope this helps!This is how I would do the initial runs. I have used this procedure thousands of times with complete success.
Good luck,
Mahlon
CYLINDER RUN-IN INSTRUCTIONS FOR CHANNEL CHROME,
CERMICROME, AND CERMINIL BARRELS
1] Install mineral oil in ALL normally aspirated engines and all Teledyne Continental turbocharged engines. Install AD oil in all Textron Lycoming turbo charged engines.
2] Start engine, run at 800 R.P.M.'s for three (3) minutes, shut down, check for leaks.
3] Start engine, run at 1,000 R.P.M.'s for three (3) minutes, shut down, check for leaks.
4] Cowl aircraft.
5] Start engine, run at 1,200 R.P.M.'s for three (3) minutes, shut down, park into wind.
6] Start engine, run at 1,400 R.P.M.'s for three (3) minutes, shut down, park into wind.
7] Start engine, run at 1,400 R.P.M.'s for five (5) minutes, run up to full power, check all engine parameters, retard power to 1,000 R.P.M. for one (1) minute, shut down.
8] Check for leaks The engine has now had it's Test Cell run time and is ready for other ground runs, taxi tests, adjustment runs, etc., observing the precautions from the post
All runs should be made into the wind.
At no time during these runs should CHT exceed 350ï‚°F.
Between all engine runs, allow adequate cool off time.
Before proceeding to next run, you should be able to hold your hand on a rear cylinder head for three to five seconds.
CYLINDER RUN-IN FOR STEEL,
NITRIDED OR REBARRELED CYLINDERS
1] Install mineral oil in the engine.
2] Start engine, run at 800 R.P.M.'s for three (3) minutes, shut down, check for leaks.
3] Start engine, run at 1,000 R.P.M.'s for three (3) minutes, shut down, check for leaks.
4] Cowl aircraft.
5] Start engine, run at 1,200 R.P.M.'s for three (3) minutes, shut down, park into the wind.
6] Start engine, run at 1,400 R.P.M.'s for five (5) minutes, shut down, park into wind.
7] Start engine, run at 1,400 R.P.M.'s for ten minutes, shut down, park into wind.
8] Start engine, run at 1,400 R.P.M.'s for five (5) minutes, run up to full power, check all engine parameters, retard power to 1,000 R.P.M. for one (1) minute, shut down.
9] Check for leaks The engine has now had it's Test Cell run time and is ready for other ground runs, taxi tests, adjustment runs, etc., observing the precautions from the post
All runs should be made into the wind.
At no time during these runs should CHT exceed 350ï‚°F.
Between all engine runs, allow adequate cool off time.
Before proceeding to next run, you should be able to hold your hand on a rear cylinder head for three to five seconds.
This is some information on running after completing the above schedule:
Knowing this crucial information allows us to make practical decisions regarding ground runs and flight profiles from the new or newly overhauled engine point of view.
To put it simply, if we get the ring to cylinder interface too hot from too hard of running, lack of cooling or another reason we will glaze the cylinder walls and prevent actual break in from occurring. Because, we are dealing with multiple independent cylinders on the engine, these conditions can happen to one cylinder, all cylinders or anything in between on the same engine. So our job above all other aspect of engine operation during the break in phase, is to keep the cylinder's as cool as possible. If we do this we will not have any problems or issues with the engine as far as break in goes. During any and all ground runs we should limit the duration and actual temps we encounter to prevent glazing from happening. We tell our customers to keep all ground runs less than 10 minutes. Don't run the engine above 2000 RPM unless you are doing a momentary full power check, high speed taxi tests or actual take off runs. If the CHT goes above 350*F or the oil temp goes above 180*F at any point during the 10 minute max. duration ground run, or at the expiration of the ten minute time limit, that run should be terminated. Then, park the aircraft faced into the wind and allow the engine to cool, until you can place your hand on the cylinder heads and barrels for 5 seconds without hurting or burning you hand and the cylinders feel relatively cool to the touch. After the engine has cooled, continue with the last run where you left off. Obviously, from what we have learned about temperature, running the engine more conservatively will not cause any problems and may even help the break in process but operating within these restrictions, on the ground, should prevent any glazing issues. These limitations apply to an engine that has had a test cell run before any ground runs are attempted. If your engine hasn't had any test cell time, then I can supply you with a ground run schedule, to replace the test cell run, which can be performed on the aircraft. If you want or need that information, just email me privately and I would be happy to send it along.
When it comes time to fly the aircraft, once again we want to observe the ground run rules, for taxi and warm up. Once we are ready to fly, we want to use full power for take off and initial climb and then we want to reduce power to climb power(normally around 85%) until we reach a safe altitude above the airport. Keep the climbs, as flat as possible, to maintain as much cooling as possible. Remember that heat is our major enemy and we can control that with climb speed. After establishing an appropriate altitude, reduce power to 65% to 75% ( preferably 75 % if speed restrictions will allow it). If we see temps, exceeding 15% of our ground run limitations, in initial flights, we should reduce power to control those temps and land the aircraft. Then, double check all cooling associated equipment, repair as necessary if you find a defect, let the engine cool off and fly it again, taking up from where you left off, observing the same restrictions. The first flight shouldn't be any longer than 10 or 15 minutes maximum, even with good cooling that would allow a longer flight. The first flight is a "test flight" and after landing you should do a through visual inspection of the engine and its installation, for leaks and any other operational issues like interference fits that showed up under power, chafing of lines etc. After the first flight issues are checked, we are ready for further flights under the same ground run and flight restriction's we have been observing. The key issue once again is heat. If we control the heat by power setting, airspeed, step climbing or any other means at our disposal we will not glaze the cylinders and we will successfully break the engine in. If we operate the engine at too low of a power setting, to seat the rings, we will not harm the engine or the eventual break in process, unless we develop enough heat to glaze the cylinders. In another words, operation at a low power setting, isn't a deterrent for break in unless we have the heat.
