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Engine break in again

rvdave

Well Known Member
I?m planning on first flight and engine breakin in the next couple of weeks in the frigid northern mich temps. Wondering if there is other than normal breakin procedures for this time of year? Nothing mentioned in what I?ve read from lycoming, aopa or otherwise. I?m expecting better cooling overall but maybe too cool for cylinders 1,2 don?t know. Should that be a concern?

Much confusing write ups about power and mixture settings for first few hours, is that all related to cylinder head temps (other than high pressures for ring seating) which once again may not be a factor for this time of year?

Can someone give me a guideline for hp/mp settings for breakin? Is 70-75% achieved by any recommended combinations of throttle/prop controls? Is it all based on chts?

Other readings say don?t worry just high power first few hours, watch out for shock cooling.
 
Hey Dave, I’m by no means an expert but I’m a huge fan of Mike Busch (Savvy Aviation). He has a wealth of knowledge.
I have broken in cylinders on IO540s and here is what I’ve done.
1. Use a single viscosity oil
2. Pre heat your engine. Oil sump element, electric blanket, radiant light etc.
3. High power settings at low altitudes so power is >70%. If possible, (WOT) wide open throttle.
4. Break in is complete when oil consumption stops

Once again Mike Busch has written several articles on this subject. Give them a once over and have fun!

Shane Adair
Still looking for a 7/7A
 
Run it hard, keep the temps inline but don't baby it. WOT if possible, and I've had great success with Phillips X/C oil for break in and after. In the previous shop I worked at we used this on procedure on all 30+ new engines and never had issues.

Mike S
Glasair III under construction
Rv-8 flying
 
Just completed our first flight a week ago. Engine is a brand new certified Lycoming O-360-A1F6 turning a Hartzell C/S prop. Pre-heated using Reiff Turbo XP cylinder bands and sump and oil cooler heating pads. Oil temp was in the top end of the yellow when we started the engine. OAT on the ground was -15C and -20C at altitude. Ran it for an hour at 75%, full rich with 100LL, kept power well up in the pattern and landed. Oil consumption was minimal, perhaps 3/16" on the dipstick.

Flew it again on Thursday for 2.1 hours in similar OAT, again at 75%. Mixture full rich (ouch she's thirsty!). Oil consumption was less than in the first hour, so between a quarter and a half quart total in 3 hours. EGTs and CHTs are flattening out, getting closer together as time goes on. As expected, #3 CHT is the warmest of the gang at about 325F Oil is Philips XC 20W50.

I don't know if we're doing it right but the engine certainly doesn't seem to mind the way it's being run. Oil consumption so far would indicate we're not glazing cylinders. Oil temp isn't as warm as I'd like it to be despite having a butterfly valve closing off the 3" SCAT tube to the remote-mounted oil cooler.
 
more comprehensive engine break-in procedure

Searched Mike Busch Savvy Aviator for engine break-in advice, nothing comes up in the savvy Aviator list, AOPA and EAA articles.

I would like to find a comprehensive new engine break-in procedure. Starting with first engine run, generally a short time run to check out everything under the cowl, to take a look at fittings and such. Then, something comprehensive about the first few hours of flight time to seat the rings, and then to the first 40 to 50 hours.

So far I have only found a few short procedure lists for different segments of break in time slots.
 
Test club

Good document - it did have one funny comment however:

WARNING
REPLACE ENGINE TEST CLUBS WITH APPROVED FLIGHT PROPELLORS BEFORE THE TEST FLIGHT.​


MrYwJsQ.png
 
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Hard Facts About Engine Break-In
TIPS
Most people seem to operate on the philosophy that they can best get their money?s worth from any mechanical device by treating it with great care. This is probably true, but in many cases, it is necessary to interpret what great care really means. This is particularly applicable when considering the break-in of a modern, reciprocating aircraft engine. Aircraft owners frequently ask about the proper procedures for run-in of a new or rebuilt engine so they can carefully complete the required steps. Many of these recommended break-in procedures also apply to engines which have been overhauled or had a cylinder replaced.

The first careful consideration for engine run-in is the oil to be used. The latest revision of Lycoming Service Instruction 1014 should be consulted for this information. The basic rule which applies to most normally aspirated Lycoming piston engines is simple: use straight mineral oil of the proper viscosity for the first fifty hours or until oil consumption stabilizes. Then switch to ashless dispersant (AD) oil.

The exceptions to the basic rule above are the O-320-H and the O/LO-360-E series. These engines may be operated using either straight mineral oil or ashless dispersant oil; however, if the engine is delivered with ashless dispersant oil installed, it must remain on ashless dispersant oil. The Lycoming oil additive P/N LW-16702 must be added to the O-320-H and O/LO-360-E engines at airframe installation, and every 50 hours thereafter or at every oil change. An FAA-approved lubricating oil that contains, in the proper amount, an oil additive equivalent to LW-16702 will meet the requirements for the additive as stated in Lycoming Service Instruction No. 1014M.

All Lycoming turbocharged engines must be broken in with ashless dispersant oil only

When taking delivery of a new aircraft, there is another point which must be emphasized. Some aircraft manufacturers add approved preservative lubricating oil to protect new engines from rust and corrosion at the time the aircraft leaves the factory. This preservative oil must be removed by the end of the first 25 hours of operation.

Each new or rebuilt engine is given a production test run at the factory before the engine is delivered to an aircraft manufacturer or customer. After installation in the aircraft, the engine is run again during the test flights. These test runs will ensure that the engine is operating normally and will provide an opportunity to locate small oil leaks or other minor discrepancies. In addition, these test runs do the initial seating of the piston rings. The rest of the break-in is the responsibility of the pilot who flies the aircraft during the next 50 hours.

A new, rebuilt or overhauled engine should receive the same start, warm-up and preflight checks as any other engine. There are some aircraft owners and pilots who would prefer to use low power settings for cruise during the break-in period. This is not recommended. A good break-in requires that the piston rings expand sufficiently to seat with the cylinder walls. This seating of the ring with the cylinder wall will only occur when pressures inside the cylinder are great enough to cause expansion of the piston rings. Pressures in the cylinder only become great enough for a good break-in when power settings above 65% are used.

Full power for takeoff and climb during the break-in period is not harmful; it is beneficial, although engine temperatures should be monitored closely to ensure that overheating does not occur. Cruise power settings above 65%, and preferably in the 70% to 75% of rated power range, should be used to achieve a good engine break-in.

Remember that if the new or rebuilt engine is normally aspirated (non-turbocharged), it will be necessary to cruise at lower altitudes to obtain the required cruise power levels. Density altitudes in excess of 8000 feet (5000 feet is recommended) will not allow the engine to develop sufficient cruise power for a good break-in.

For those who still think that running the engine hard during break-in falls into the category of cruel and unusual punishment, there is one more argument for high power settings during engine break-in. The use of low power settings does not expand the piston rings enough, and a film of oil is left on the cylinder walls. The high temperatures in the combustion chamber will oxidize this oil film so that it creates a condition commonly known as glazing of the cylinder walls. When this happens, the ring break-in process stops, and excessive oil consumption frequently occurs. The bad news is that extensive glazing can only be corrected by removing the cylinders and rehoning the walls. This is expensive, and it is an expense that can be avoided by proper break-in procedures.

To summarize, there are just a few items to remember about engine break-in:

If a preservative oil has been added by the aircraft manufacturer, drain it no later than the first 25 hours of operation;
Follow the engine manufacturer?s recommendation regarding the oil to be used for break-in and the period between changes;
Run the engine at high cruise power levels for best piston ring/ cylinder wall mating;
Continue break-in operation for 50 hours or until oil consumption stabilizes. These simple procedures should eliminate the possibility of cylinder wall glazing and should prepare the engine for a long and satisfactory service life.

Copied from a Lycoming bulletin.
Sorry I couldn?t find the Mike B. Info. I?ll keep looking....
Shane Adair
 
And to build on Paul's comments, glazing of cylinders often manifests itself through oil consumption which does not plateau after a reasonable number of hours of break-in time. That and low compression, if one takes the time to do a compression test.

With reference to my comment previously quoted, our oil consumption rate is not consistent with glazing, and our CHT's are well below the limits previously discussed on this forum by Mahlon Russell as being associated with causing glazing.
 
I have a Lycoming o-360 with about 60 hrs. Oil consumption is high-about a quart every 4 hrs. It seems to all be going out the breather tube. And, no, I am not over filling. At just 6 or 5.5 qts, it still uses oil rapidly. I suspect the rings have not properly seated, possibly due to glazing. I bought the plane with about 40 hrs on it, so I don?t know what it?s break-in process was. I have been using Aeroshell 15W50, not mineral oil, after initially assuming break-in was done. The cylinders are nitride I think. It may have been run at excessive CHTs during break-in, causing glazing. I am about to do a borescope and compression test. My question is what to do, assuming glazing has occurred. Would going back to mineral oil do anything, or is it too late if already glazed? Are there any other possibilities than glazing?
 
Glazing is caused by heat and a thicker than normal coating of oil on the cyl walls. Before the rings have seated, there will be a thicker than normal coating of oil on the cylinder walls. If this thick coating of oil is exposed to heat above the critical level, it will oxidize and glazing occurs, halting the break in and causing high oil consumption. I cant give exact numbers, but it is near the 450* level. It is a bit variable, as the critical temp is measured on the barrel wall, and that temp does not move in a linear fashion with the CHT in rising or declining temps. Once the rings seat, the thinner oil layer is pretty much resistant to glazing, even above 450*.

During my O-320 break in, I let two cylinders get to the neighborhood of 450 for about 15-30 seconds before noticing it. Both cylinders were glazed and required a re-hone.

It is purely a heat issue and it doesn't take much time to do it.

Larry
 
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I have a Lycoming o-360 with about 60 hrs. Oil consumption is high-about a quart every 4 hrs. It seems to all be going out the breather tube. And, no, I am not over filling. At just 6 or 5.5 qts, it still uses oil rapidly. I suspect the rings have not properly seated, possibly due to glazing. I bought the plane with about 40 hrs on it, so I don’t know what it’s break-in process was. I have been using Aeroshell 15W50, not mineral oil, after initially assuming break-in was done. The cylinders are nitride I think. It may have been run at excessive CHTs during break-in, causing glazing. I am about to do a borescope and compression test. My question is what to do, assuming glazing has occurred. Would going back to mineral oil do anything, or is it too late if already glazed? Are there any other possibilities than glazing?


You can see glazing directly through the sparkplug hole with a flashlight. Shiny metallic color indicates no glazing. An opaque yellowish, tan color on the walls is glazing. 100% glazing is uncommon. You will usually have patches or areas of glazing with other parts un-glazed. Glazed cylinders will typically show oil pooling at that piston and wet, oily plugs. Glazing typically does not negatively impact compression.
 
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I have a Lycoming o-360 with about 60 hrs. Oil consumption is high-about a quart every 4 hrs. It seems to all be going out the breather tube. And, no, I am not over filling. At just 6 or 5.5 qts, it still uses oil rapidly. I suspect the rings have not properly seated, possibly due to glazing. I bought the plane with about 40 hrs on it, so I don?t know what it?s break-in process was. I have been using Aeroshell 15W50, not mineral oil, after initially assuming break-in was done. The cylinders are nitride I think. It may have been run at excessive CHTs during break-in, causing glazing. I am about to do a borescope and compression test. My question is what to do, assuming glazing has occurred. Would going back to mineral oil do anything, or is it too late if already glazed? Are there any other possibilities than glazing?

Before doing anything else, I suggest you stop using the multigrade oil and switch to Aeroshell 100 (straight mineral), and see what happens.
Whether it gets better or not, I would recommend you not use the multi weight.
 
Before doing anything else, I suggest you stop using the multigrade oil and switch to Aeroshell 100 (straight mineral), and see what happens.
Whether it gets better or not, I would recommend you not use the multi weight.

Why? Where’s the data to back up that statement?
 
The only way to fix glazing is to rehone the cylinders.

Contrary to popular belief cylinders break in seconds and minutes, not hours of "running hard".

Overhaul an engine and put your ear on a cylinder while pulling the prop thru, then run it once. Big difference how it sounds.

Keep initial runs short and under 300 CHT. Let it cool completely before a subsequent run. I've never had an engine use oil after an overhaul doing breakins this way.
 
Break in

Phillips XC 20w50 has become widely used for break in in recent years. The goal for break in should be to keep the CHT below 400. A very momentary excursion to 425 should not cause a problem.
Mahlon Russell has a ground run and flight profile for break in which I followed to the letter with excellent results. I believe it can still be found on Lycoming yahoo forum.
 
Personal conversations with engineers and regional reps from Lycoming.
Based on what I have been told, I do not use Aeroshell multi weight in our fleet of airplanes.

I agree. I am not a fan of Aeroshell. I don't know of any other oils, aircraft or otherwise, that will varnish an engine like Aeroshell does.
 
break-in process

...
Contrary to popular belief cylinders break in seconds and minutes, not hours of "running hard".

Overhaul an engine and put your ear on a cylinder while pulling the prop thru, then run it once. Big difference how it sounds.

Keep initial runs short and under 300 CHT. Let it cool completely before a subsequent run. I've never had an engine use oil after an overhaul doing breakins this way.
Can you give more details about your break-in process? If I understand you correctly, it sounds like it could easily be done on the ground.
 
re-use oil

Is it okay to catch and reuse the oil after the 5 minute ground test? I see Lycoming suggest full power ground test for 10 seconds. Then check the screen or filter. Pulling screen or filter will drain out most of the oil. Can I catch and re-use the oil or throw it away? Seems ashame to throw away 8 quarts of oil after a 5 minute ground test.

I broke in my O540 a couple years ago but can't remember if we did much ground test. I don't think so. But that was an engine replacement on a production plane. I've completed 2 ground idle test on my 7A and am getting ready for first flight. I'll do one more ground test to full power for 10 seconds per Lycoming. Then check everything including pulling screen to look for metal.
 
Can you give more details about your break-in process? If I understand you correctly, it sounds like it could easily be done on the ground.

What I posted is all it is. Make a couple runs, don't exceed 300 CHT. Simple.
 
I agree. I am not a fan of Aeroshell. I don't know of any other oils, aircraft or otherwise, that will varnish an engine like Aeroshell does.

I was NOT a believer in this opinion... until I had my first engine (a C85) overhauled. It was all gold-coloured on the inside. If any of you have seen the aluminum foil backing on insulation blankets in airliners from the era when cigarette smoking was allowed, THAT's what my engine looked like. Gold varnish everywhere.

Then the owner of the shop showed me a very similar engine they had torn apart immediately before mine. Clean, shiny metal inside, looked almost like brand new. That engine was an O-200 from a C150 used as a trainer - it had gone well beyond TBO. The oil used was Phillips XC 20-W-50.

I simply couldn't believe the difference between an engine that ran AeroShell and an engine that ran Phillips. I now use Phillips exclusively.

As for break-in procedure, it's really simple, as Bob said. Limit ground runs to 300 degrees CHT, no matter what. Don't start the next ground run until you can comfortably hold your hand on the cylinder for 20 seconds or more. This will be more than sufficient to protect the cylinders from glazing. In the case of our O-360-A1F6, I ended up doing 10 ground runs, including six attempts to make full power. It turned out I needed to adjust both the prop low pitch stops and the governor setting in order to make the full 2700 RPM.

The key is limiting duration of ground runs at ANY power setting and using that 300 degrees as an ABSOLUTE CHT limit for ground ops. If, for your first flight, ATC delays your takeoff and you see CHT's rising about 300, if you're not sitting on the button of the runway and cleared for takeoff, shut the engine down and let it cool.

I posted earlier in this thread about our in-flight break-in procedure (fly it like you stole it and like somebody else is payin' for the gas!). Now, with 90 hours on the tach, oil consumption is about one quart per 20-24 tach hours.

Adhering to these very simple rules... just... works!
 
This is great information. So I understand adhering to the max 300* CHT rule but can you please describe in further details as to what power settings you'd want to achieve this. Would you want to vary the throttle (RPM's)?, full power? half throttle? Does mixture settings make a difference?

Thanks,
Mark
 
As for break-in procedure, it's really simple, as Bob said. Limit ground runs to 300 degrees CHT, no matter what. Don't start the next ground run until you can comfortably hold your hand on the cylinder for 20 seconds or more. This will be more than sufficient to protect the cylinders from glazing. In the case of our O-360-A1F6, I ended up doing 10 ground runs, including six attempts to make full power. It turned out I needed to adjust both the prop low pitch stops and the governor setting in order to make the full 2700 RPM.

On these ground runs did you install cowls and baffles? Lycoming says do 10 seconds at full power then check for leaks. Are cowls and baffles needed for this kind of ground engine test run?
thanks
 
New vs Rebuilt Engine Break-in

Same question, I'm within weeks of first flight and I'm trying to make sure I've done everything necessary for the engine.

Do I need to do a 10 second full power engine test and then oil drain and inspection on a new IO360 from Lycoming? The documents offered on earlier links including Lycoming 1427C are for "field overhauled" engines. But mine is new from Lycoming. So did the engine get tested on the test stand sufficient at Lycoming so that I should do just a couple idle tests and fuel flow test and then go for first flight test which will start engine break-in? And I'll do a few seconds of full power at prior to taking off to ensure engine can do full power. Does this sound right?
 
After reading these last couple of posts I had flashbacks to that same set of questions from years ago. You're sitting on a LOT of dollars worth of engine and the last thing you want to do is harm that brand new engine before you even get a chance to get into the air.

Been there, done that... Understand your position entirely.

When we're in that mindset of "fear of doing harm" it's really, really difficult to believe that engine break-in can be boiled down to a very small set of "Rules and Recommendations". But it can be, and has been, very successfully, for many years!

Firstly, to be clear, a "new" engine from Lycoming has been "run in" for you by Lycoming. The "Run A minutes at B RPM, then C minutes at D RPM" is all done, so put all that behind you.

What you have to do now is to ensure the good work that was started at the Lycoming factory doesn't get undone by you before you get the rings fully seated. That process of seating the rings is "break-in".

So the short answer is that you need to do engine runs necessary to satisfy yourself that all systems are performing as they should. While doing the engine runs you should keep CHT below 300F - that seems like an almost universally-recognized recommendation.

How fast you spin the engine is up to you. Personally, I would not take off in a brand new airplane with a brand new engine unless I knew the engine was making full power. One can do a full-power engine run without exceeding 300F CHT. Manage your time wisely while running the engine. Preheat as necessary to get the oil up to a good temperature so you don't have to run the engine to heat the oil - having to run the engine a long time to heat up the oil will decrease the amount of time available at higher power settings before the CHT rises to 300F.

As for baffling... Consider baffling one of the "systems" you're checking out and breaking in. It should be in place for your engine runs.

Engine cowl? That's aircraft-dependent to some degree. At a personal level I was uncomfortable running at full power with the cowl off, so I ran with the cowl on and accepted that I might have a short running time available. Of course the airplane was parked into the wind and the oil door was opened up following the run to get the engine cooling down as well as possible after shut-down. For prior runs up to 2000RPM the cowls were off and no harm was done.

Run the engine to ensure it will idle, that both ignition systems are functional, that the mixture control and carb heat work, and that a constant-speed prop will cycle. From this list you can see that most systems can be checked out at speeds below 2000RPM. That leaves only a very brief run up to full throttle to ensure you're getting the recommended static RPM and that the engine is happy making that much power. You'll be surprised how the airplane will be bucking and rocking at those high power settings, so give yourself confidence and an extra margin of safety by chocking the airplane well and tying it to something very secure. I used a tractor, parked sideways behind the airplane, and stout ropes from the tractor to the main gear legs, and was still surprised by how much slack was taken up in those ropes at the gear legs were flexed by the prop thrust.

In our case both the prop low pitch limit and the governor needed to be adjusted, so, in all, we ended up doing 10 engine runs before the first flight. Never during these runs did CHT's get to 300F. Never was the engine run a subsequent time unless I could comfortably rest my hand on the cylinder head and hold it there (think "leaning on the engine while talking to a buddy" - if you can't hold your hand there that long, the engine isn't cool enough to run again).

By following these simple methods you'll get a good set of ground runs done, you'll develop confidence that everything is working as it should, and you'll know that when you're ready for your first flight all you need to concentrate on in terms of engine management for break-in will be to "fly it like you stole it", watching CHTs don't climb above recommended limits (I used 425F as my absolute max and never hit that temperature but did hit 410 very briefly).

In our case, following these simple steps yielded oil consumption better than 20 hours per quart and compressions that are terrific.

In short, don't let fear override rational thought. Run your engine with confidence and with the knowledge that it can and will break in well if you follow some very simple guiding principles. It really doesn't have to be complicated, so don't get caught up in over-thinking it. Enjoy the feeling of your engine doing its thing, and doing it well!
 
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leaf blowers

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.
 
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.
 
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.
 
Prop adjustment

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
 
Start

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.
 
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.
 
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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.
 
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
 
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.
 
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.
 
So the short answer is that you need to do engine runs necessary to satisfy yourself that all systems are performing as they should. While doing the engine runs you should keep CHT below 300F - that seems like an almost universally-recognized recommendation.

How fast you spin the engine is up to you. Personally, I would not take off in a brand new airplane with a brand new engine unless I knew the engine was making full power. One can do a full-power engine run without exceeding 300F CHT. Manage your time wisely while running the engine. Preheat as necessary to get the oil up to a good temperature so you don't have to run the engine to heat the oil - having to run the engine a long time to heat up the oil will decrease the amount of time available at higher power settings before the CHT rises to 300F.

Sorry, re-opening this old thread because...well, it's full of great info. Does anyone have any tips and techniques around doing a full-power engine test on the ground while keeping CHT this low? It seems like an impossible balancing act. Data recorded from my most recent taxi test showed my (Cowled RV-7, Lycoming IO-360-M1B) hottest CHT reaching 300 after 5 minutes of running at 1100 RPM from a cold start. Surely doing any kind of full power test would quickly blow through 300, 350, then 400 before the test bore useful results.
 
Sorry, re-opening this old thread because...well, it's full of great info. Does anyone have any tips and techniques around doing a full-power engine test on the ground while keeping CHT this low? It seems like an impossible balancing act. Data recorded from my most recent taxi test showed my (Cowled RV-7, Lycoming IO-360-M1B) hottest CHT reaching 300 after 5 minutes of running at 1100 RPM from a cold start. Surely doing any kind of full power test would quickly blow through 300, 350, then 400 before the test bore useful results.

Anecdotal, but both aircraft I've flown with new engines, I did the fuel flow tests, then did brief runups to full power (and shut-down to let the engine cool). The first extended tests (more than 15 seconds) at full power occurred on the takeoff runs and first flight(s).

What are you gonna learn by ground running the engine at full power for more than a few seconds?
 
Anecdotal, but both aircraft I've flown with new engines, I did the fuel flow tests, then did brief runups to full power (and shut-down to let the engine cool). The first extended tests (more than 15 seconds) at full power occurred on the takeoff runs and first flight(s).

What are you gonna learn by ground running the engine at full power for more than a few seconds?

Agreed. You need to check MAP, rpm, prop sweep, maybe a mixture sweep, that's it.
 
Agreed. You need to check MAP, rpm, prop sweep, maybe a mixture sweep, that's it.

The list is probably a little longer (oil pressure, fuel pressure, and fuel flow with the engine running come to mind) but it is mostly just checking that nothing is out of sorts.
 
Yea, I don't want to get into a flame war over the necessity of testing at full power. There have been posters here who claim it can be done while also keeping CHTs low, and I'm just looking for more details about how that can be achieved. Obvious things that come to mind would be 1. tie/chock it where you need it without taxiing there which heats up the cylinders, 2. run it facing into the wind on a windy day if possible.
 
I built a cooling shroud out of some old scrap aluminum I found at a junkyard.

http://www.rv8.ch/engine-cooling-shroud/

I did a few quick full power runs with the aircraft tied to my car.

If you choose to go this route, make that shroud strong. I was surprised at how much force is on it. If it came off, it was taking the windscreen and probably the tail with it.

I tied the aircraft at the top of the gear legs without the fairing on there, and ran the straps through the tailwheel, to keep the tailwheel low. Tied to the frame of the car.

Full power, when tied down, is scary. If anyone has ridden rodeo, or broken horses, then this sensation will be familiar.

It was so scary that I put probably 10-15 minutes total time at full power over a period of sessions. It was plenty to ensure that all was ok with the engine before the first flight, but probably not needed. Unless there was a very specific reason to run the engine for a long time on the ground (I can't think of one) I would not use this system again.
 
For what it's worth - the brake pads need to be broken in as well before flight - this entails a couple good braking runs. My initial full-power engine test runs before first flight consisted of wide open power for 5-6 seconds down the runway, then using the speed gained to break-in the brake pads over a couple runs.

Be prepared for a first flight, just in case your throttle hangs open.
 
It certainly wouldn't be the first time a 'fast taxi' test turned in a first flight :eek:
RV's accelerate quickly!
 
For what it's worth - the brake pads need to be broken in as well before flight - this entails a couple good braking runs. My initial full-power engine test runs before first flight consisted of wide open power for 5-6 seconds down the runway, then using the speed gained to break-in the brake pads over a couple runs.

Be prepared for a first flight, just in case your throttle hangs open.

OK, so before we get hundreds of guys thinking that you HAVE to do full-power accelerations down the runway before first flight to break in your pads….you don’t. I’m glad this worked for you, but I find that the brake pads will do just fine with a couple of accelerations to 20 mph and some stops on the taxiway. Or frankly, nothing at all - they’ll break in on your first landing.

High Speed taxi testing (under whatever guise) has proven time and time again to be a great way to create a crisis that folks don’t need.

Paul
 
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