Engine break in again

[rdrcrmatt]

Originally Posted by rv8ch

Just curious, if the major issue with ground ops on a new engine is cooling, couldn't we hook up some kind of ducted leaf blower cooling system that would move enough air over the engine to eliminate this problem? Those things seem to move a lot of air, and are really cheap.

there already is a really big fan in front of the cowling that doesn't do a good enough job cooling at WOT.

[James Ball]

The list of service information letters for Titan engines by Continental Motors is found here;

http://continentalmotors.aero/titan/documentation.aspx

The break in instruction is the second one from the top.

[Canadian_JOY]

Originally Posted by rv8ch

Just curious, if the major issue with ground ops on a new engine is cooling, couldn't we hook up some kind of ducted leaf blower cooling system that would move enough air over the engine to eliminate this problem? Those things seem to move a lot of air, and are really cheap.

it's just a LOT easier to limit your engine runs. Plan in advance what you want to accomplish for each run, how the run will be conducted, what your limits and expected timing will be, then follow the plan. It also helps to have internal and external video cameras set up so you get maximum value from each run.

Once you get the hang of it, you'll find that limiting engine run times based on CHT is a pretty easy way to do things.

[amerkarim]

Hi All,

Many thanks for the tips, they make a lot of sense. Especially about the CHT and glazing.

Why on a ground run do you limit the CHT to 300 to stop glazing and yet in first flight you go to over 400 ?

I am planning to put the wings on my RV10 and do my first engine start this weekend, fingers crossed it all goes well. I have 2 electric air guns and am planning to use them through the cowl openings after shutdown to help cool the engine cylinders down quickly. I will let you know how I get on with that idea and if it makes a difference.

With regard to the Prop governor. What am I looking for when I cycle the prop? What do I want to check and adjust if necessary?

Thanks

Amer

[Electrogunner]

Originally Posted by amerkarim

Hi All,

Many thanks for the tips, they make a lot of sense. Especially about the CHT and glazing.

Why on a ground run do you limit the CHT to 300 to stop glazing and yet in first flight you go to over 400 ?

I am planning to put the wings on my RV10 and do my first engine start this weekend, fingers crossed it all goes well. I have 2 electric air guns and am planning to use them through the cowl openings after shutdown to help cool the engine cylinders down quickly. I will let you know how I get on with that idea and if it makes a difference.

With regard to the Prop governor. What am I looking for when I cycle the prop? What do I want to check and adjust if necessary?

Thanks

Amer

Amer
I would highly suggest you have the cowling off for first start and have an observer/s looking for abnormalities and leaks. Last thing you want is a fuel leak hidden by your cowling while you are happily sitting there. Limit your first start to less then a minute, then check everything fwf before next start.

[Canadian_JOY]

Originally Posted by amerkarim

Hi All,

Why on a ground run do you limit the CHT to 300 to stop glazing and yet in first flight you go to over 400 ?

I am planning to put the wings on my RV10 and do my first engine start this weekend, fingers crossed it all goes well. I have 2 electric air guns and am planning to use them through the cowl openings after shutdown to help cool the engine cylinders down quickly. I will let you know how I get on with that idea and if it makes a difference.

With regard to the Prop governor. What am I looking for when I cycle the prop? What do I want to check and adjust if necessary?

Thanks

Amer

Amer - cylinder head temperature is one factor. What we haven't been adding to the discussion is ICP - internal cylinder pressure. With high power being generated, you have both higher temperatures and MUCH higher internal cylinder pressures. It's the latter that's pushing the rings out against the walls of the cylinders, wearing in the mating surfaces... this is break in.

What you don't want is high temperature and low pressure. Think of what it's like when you take very fine grit sandpaper and rub it over a course surface very quickly. You'll get that surface up to a shine on the tops of the ridges, but you won't reduce the height of the ridges. That's glazing.

As for the C/S prop, you are checking to see that it will cycle. It will take as much as 2000RPM to get the prop to move. This is not something you want to do on your first engine run. On subsequent low-power runs all you are looking for is that the prop moves. You don't need to cycle it deeply so as to lose a lot of RPM, just enough to know you've got oil flowing up to the prop hub and that the prop hub is working as expected.

Later on, when you're ready to do a full-power run, you'll be checking to make sure the governor actually governs the prop RPM so you don't have an overspeed condition. The prop itself has internal low-pitch stops which mechanically limit the maximum RPM - you should also check to ensure these are set properly. An engine overspeed event can be a very expensive thing indeed.

Agree entirely with Electrogunner - first few engine runs should be done with the cowl off, with a knowledgeable observer nearby, with fire extinguishing equipment available. Keep it short. You're looking for oil pressure coming up to a normal level, that the engine runs, that fuel systems are not leaking. Many folks recommend not going over 1300 or 1400 RPM on this first run, just enough to ensure the engine responds to throttle changes, including coming back to something like an idle. Don't expect it to idle at low RPM - a brand new engine will likely cough and sputter and not want to run below perhaps 800 RPM - lower, smoother idle will come with a warm engine and a fuel delivery system that's been purged of all the "stuff" that accumulates during the build cycle. Do a mag check (at perhaps 1300 or 1400 RPM) to ensure both ignitions are actually firing their plugs, then come back to 1000 RPM to perform a live mag check to ensure you don't have a hot mag. Finally, check to ensure the mixture control will actually cut off the engine at the idle-cutoff position.

Once you've done this, walk away from the airplane, sit down and let the grin take a good set on your face. It will feel VERY good. Then get the airplane back in the hangar and go over everything in the engine bay with a very fine-toothed comb, looking for leaks (oil, fuel, intake, exhaust), loose fasteners, chafing etc. Give it such a good looking over that you are fully confident that your next engine run will be a "clean" run with no problems.

[Scott Hersha]

What Mark just said. Limit engine run time before first flight, and then run it hard - over the airport for an hour if possible. You probably shouldn’t cycle the prop because it takes too long at too high a power setting. Mine still won’t cycle until at least 2000 RPM, and it was that way on my last three RV’s, all with different props and governors. That being said, be prepared on your first takeoff for some prop cycle surging as oil finally gets up to the prop dome and the gov/prop tries to find an equilibrium.

[amerkarim]

Thanks guys,

Makes perfect sense now and am looking forward to it at last.

Will follow the above instructions and keep everything crossed it goes well

Kindest regards

Amer

[Kellym]

Originally Posted by Scott Hersha

What Mark just said. Limit engine run time before first flight, and then run it hard - over the airport for an hour if possible. You probably shouldn’t cycle the prop because it takes too long at too high a power setting. Mine still won’t cycle until at least 2000 RPM, and it was that way on my last three RV’s, all with different props and governors. That being said, be prepared on your first takeoff for some prop cycle surging as oil finally gets up to the prop dome and the gov/prop tries to find an equilibrium.

What prop governor do you have? I have no trouble cycling my prop at 1700. I have MT governor and MT prop. Some old design prop governors do take a bit more rpm. If you pull prop all the way coarse at 1700, you should get rpm reduction within 10 seconds or less. Avoid letting rpm decrease more than 200 rpm. I don't recall any issue cycling on second and later flights. Followed directions to not cycle on first flight.

[Scott Hersha]

Governors - Woodward, Hartzell, & Jihostroj. All have behaved pretty much the same. Won’t cycle at 17-1800 RPM on runup, using a Hartzell, or Whirlwind prop. They try to cycle at 2000 RPM, but it’s barely doing anything. Most of my RV buddies at my airport experience the same thing.