I’ve never heard of an in-flight mag-check; ROP or LOP; fascinating. Further, tower controllers are apparently running Lean Of Pastry almost constantly, no matter how frequently they “windmill” about it. 😜✈️😎👍
Great timing! I watched Mike Busch's recent EAA webinar on mag failures and he discussed this very procedure. Your video is much more informative with regard to actually doing the check and the possible problems encountered.
Very well explained. I may add that the extra variable is altitude - the higher you are, the more demanding the test is on an ignition system due to reduced air pressure. The distributor in our mag relies on jump gap inside the cap to deliver the spark to each cylinder and jumping the gap for electricity diminishes with reduction in air pressure (hence the turbo planes have pressurized mags). Therefore, I tend to do this at higher altitudes to really stress test the system. If you fly a turbo engine, doing this test at altitude will also check that your mags are properly pressurized.
Thanks, Jeff. Remember, shutting down the engine isn't part of the normal LOP mag check. It is merely the recover from an unlikely bad issue you might find while running the check, which in most cases is no more fearsome as the mag check on the ground. Best regards, Martin
Great video Martin... I flew one time with someone who did an inflight mag check LOP when I first bought Lola, but didn’t understand why. Thanks for this.
I did this yesterday on my Cherokee 235. I installed two new slick mags in April so wasn’t concerned if my mags were bad but thought it would be a good idea to check the system as a whole. I was LOP, put my EDM-830 into normalize mode and when I switched to the left mag and the EGT,s shot up to about 1700. The right mag check was a normal increase. I suspect the timing is off on the left mag?
Hi Tyler, sorry for the long delay in responding - I just now saw your question. Mag timing could explain what you observed, but I would not rule out other explanations. Have you had a chance since then to investigate further? Regards, Martin
Just lean it on the ground and check it there. There’s absolutely no reason to be turning off any part of an operating system in flight, unless it’s a failure and part of a published checklist.
Chris, I think I was pretty clear about what the reason is in this video. You are right of course to weigh the risks against the benefits in a given situation - say, while over the middle of Lake Michigan, vs. over an airport with a nice, paved runway - and in some cases I would agree you should save this check for another flight or another time. But simply saying "there is no reason" is not something I agree with. - Martin
Heh - I once had this problem with an old, beyond-retirement U-Haul truck. The coil wire was loose, so it was firing intermittently, and it sounded like I was lighting firecrackers the whole trip.
So it appears the only difference of doing this more sensitive check in the air and on the ground is (a) more power and (b) leaner mixture. Could you still get more proactive results as you explain in the ground check by adding power and/or leaning the mixture then doing magneto checks? Either way, I'm apt to try the experiment with the criticals of recovery procedure in mind!
In theory, I guess - but I would not want to do a ground run-up like this on a regular basis. I feel bad enough for my prop at 1,700 RPM; running at 60% power or so and then taking the time to lean precisely to an appropriate cruise mixture with the brakes locked on the run-up pad - that's not something I like to do to my airplane. Regards, Martin
Am I correct in inferring that this would also potentially indicate a problem with a spark plug? I am also trying to figure out what about the mag itself would cause one plug/cylinder to not ignite properly - presumably the mag not producing enough voltage and/or power(amps) to trigger the spark on the most resistive plug/cylinder. Yet another indication that I need to learn more about how mags actually work!
Yes, Thomas, a bad spark plug is one of the possible contributors to an ignition system problem. It could also be a magneto, or the ignition harness (wiring), or the ignition switch. Regards, Martin
This makes sense if the goal is to maximize up time. But if the goal is to reduce risk of in-flight engine issues, this seems to add risk rather than reduce it.
And what risk would that be? That the engine stops making power on one mag? Yes, that is a possibility, but it'll immediately come back alive when turning to both mags. And at least then you KNOW there is a problem, I prefer that over continuing the flight without any clue that I have a mag issue. Regards, Martin
Patrick, an alternative solution is to pull the throttle back to idle power without first pulling the mixture. Then turn MAGS to BOTH, and reapply power. This still provides some protection for your exhaust (vs. restoring ignition at full cruise power). - Martin
That was great, Martin! I have been told that it's good to get 10 or 20 "samples" into your engine monitor logs when doing this test. I believe my JPI 800 is set for 2 seconds (the min), so I wait for 20-30 seconds on each mag. When you upload the file to Savvy Analysis, there is a "Mag Check" button (the "M" in the circle) which changes both plots to be EGT and puts the odd cylinders on top and even cylinders on bottom. This can really help point out if there is a problem developing - even if all 6 keep firing as they should thru the test. The other comment about all mag checks (ground or LOP in air) I would add is this: I "normalize" my engine monitor before the check. I then look for all 6 to rise together when on each mag. I think your display (the 930) has better resolution so it does not matter. I will say that one way an engine monitor pays for itself is when you do a mag check and one EGT bar goes to 0. It's so great to know the exact cylinder and spark plug that stopped firing. That alone probably saves an hour time knowing exactly where to start looking for issues.
Thanks for the additional insight, Jim - that's a good addition. Yes, I have played with this feature on the Savvy website, and I agree it can be a useful tool. Best regards, Martin
Hi Gabe. You may be right, but I have not heard of this. Mag issues happen somewhat regularly, and I bet when they do, most pilots don't shut down but simply go back to BOTH. So one would expect that we hear about exhaust damage from a failed ground run-up every now and then - and I just don't remember ever hearing about it. Kind regards, Martin
@@martinpauly I find split mufflers fairly often or bulged mufflers on flight training aircraft for said mag switch mistake. I do wonder what its going to be like with a surefly on my Mooney. Doing install right now.
Great video Martin as always and thanks for having the guts not only to turn off both mags in flight to make your point, but also posting it for the benefit of the community (knowing you would get some people objecting to that). A question: You said LOP and WOT. How would this test work at a lower altitude with reduced throttle? To be clear, not that I would really do this test at low altitude but just curious about the implications of doing it with lower MP at lower altitude (still LOP)?
I want to start testing the mags LOP as you explain for a while, will do next flight. But this bring up a question. What about doing the LOP test on the ground like a regular runup?
Martin , you should team up with Mike Busch , you both know how to transfer your aviation wisdom except your videos creating great real time experience . LOP was excellent as well . TY .
Great video! Great way to show how the world does not stop just because either spark or fuel is interrupted during a normal flight. This would be a great emergency procedure to practice to understand the relation between airspeed, engine speed, manifold, and RPM with the absence of power. Thanks again for your commitment to great power and engine management and the relation between them both! Us here in Oregon would love some pastries! Great out takes! Thanks again, Martin!
Thanks, Kyle. You are right, there is a lot of uncertainty over what happens if or when the engine stops making power. In most cases, the airplane simply turns into a glider, but the laws of physics and aerodynamics still apply. And restarting a piston engine in flight isn't a big deal - fuel, air, compression, and spark, and we are in business. - Martin
Very nice work! Impressive. So clear, concise and really great to watch it applied during an actual flight. I hope you do more on engine analyzer interpretations...isolating bad spark plugs, catching clogged injectors, etc.
FYI: the air-to-fuel mixture in a reciprocating combustion engine is 14.7:1. And that's a weight ratio, not a volume one. It's an aerosol more than anything else. No "washing down" of anything.
Martin, This was a great demo! Most of us have experienced the hot start in fuel injected engines, where it may be very difficult to start a hot engine due to the fuel vapor in the lines. I would be extremely worried about having a hard time restarting the engine after shutting it down. Or, does the fact that you're airborne, with lots of cooling air flowing over the engine make it very easy to restart without the usual hot engine starting fuss? My Piper Lance can be a real bear to restart if it's hot.
Good question, Eric. I have experienced the dreaded hot start many times in various aircraft. There are three reasons why this is not a concern when doing a restart in air: (1) Your propeller is windmilling, giving your engine better compression and your magnetos more power for the spark plugs than your starter motor is able to provide. (2) When in air, there is a lot of air coming in to cool the engine, to the point where the worry isn't "hot start" but "excessive engine cooling". Certainly the cooling air coming into your engine compartment will prevent vapor locks from building. (3) Typical hot starts end up being difficult because, in an effort to overcome the vapor locks, pilots end up with a flooded engine. When restarting in air, the engine will restart the moment you push the mixture knob far enough forward to have a combustible fuel/air mixture. Still if you are worried, you may want to recover by only pulling the throttle back, not the mixture. If you reduce power to a minimum, you will likely not harm your exhaust when the the ignition system is restored to full operation. Regards, Martin
Now I'm running LOP (Lean Of Pastry)!! 8) Just curious, have you vetted that procedure before putting it out here? I only ask because I don't recall seeing it done before. It looks very valuable for early diagnosis. Thanks!! JMHO --gary
In-flight LOP mag checks have been recommended for years by people who understand aircraft piston engines a lot better than I do. Mike Busch, John Deakin, and the APS (Advanced Pilot Seminar) crew. I did not invent anything new, I merely put it into tutorial format. - Martin
Interesting video... we run a Lycoming O-360 in our Grumman AA-5B. Although there's nothing in the POH that mentions being able to run LOP, many experienced Grumman owners know that running LOP is not an option in a Tiger. The engine just complains a lot when trying to set LOP. It seems carbureted engines tend not to like running in that mode. This video is a bit timely... a few weeks ago, my son and I were flying our Grumman on a beautiful, severely clear VFR day to go do some practice instrument approaches up at the Cheyenne airport, about a 30 minute flight from our home airport. As we got to our assigned cruise altitude of 8,000', I noticed the engine running a bit rougher than normal. Since it was quite chilly outside, I suspected possible carb ice, so I applied carb heat. As I went through the normal leaning procedure for cruise, we both noticed that the engine still would not run smoothly. RPM was indicating normal and all gauges were "in the green", but something still didn't feel right. EGTs and CHTs were also reading differently. The number one EGT and CHT was reporting "cooler" than normal. I asked my son what he thought and he confirmed my suspicion. The engine was not running normally. We cancelled IFR and declared an emergency so that we could have priority getting back to our home airport. We asked if we could enter the Denver Class Bravo at 8,000' so that we could have plenty of altitude in case the engine quit. 6,500' is pattern altitude at our home airport. ATC was quick to clear us in unrestricted. We landed without incident, but were greeted by a plethora of fire equipment as we exited the runway. Anyway, upon inspection of the engine via a compression check, we found that the exhaust valve in the number one cylinder was sticking open. We've since taken the cylinder off to have it serviced. I'm hoping to get my airplane put back together soon, so we can enjoy the upcoming spring weather. Thanks again for putting this video together. Fly safe and fly often! PS - If you're ever in Denver at KBJC, look us up... we LOVE fresh pastries!
Hi Gordon, glad to hear your emergency had a good outcome. Many (maybe most?) engine failures result in partial power, not a complete power loss. There may be a LOT of roughness, but at least you can fly to an airport and land. - Martin
Very informative video and well explained! Taking about fuel igniting in the exhaust... I think everybody who has owned a motorbike with a straight through pipe has at least once turned the ignition off while riding with the throttle wide open, left it for a few seconds and then turned it back to enjoy the nice bang and sometimes flash out the back 😂 Great in tunnels 😎
Thanks Martin! Your videos are so helpful from a technical standpoint! Keep on posting! I’m a new 182 owner and I value your wisdom to help me manage my airplane! (But I’m still a ROP guy… we’ll see!). Resist the temptation to make your videos more fancy with music, pretty girls, and exotic destinations! All we care about is how to be the best pilot possible!!!
Thanks for the kind feedback, JD, and maybe you'll try LOP one of these days in your Skylane! (Hint: It's not about damaging your engine or not, and more about whether your engine will get to the lean side of peak before it runs rough. If it does get there, there's no harm.) Regards, Martin
Very interesting video Martin. I watch your videos often, but came across this one via a search I made, namely “magneto ground check”. Now, I’m an old timer who can no longer fly except vicariously through young, You Tube whippersnappers like you. My father owned a flight school/charter operation in the Seattle area from the early 50’s through the mid 70’s. Now, to the point. If I remember right, as a part of our engine run up, maybe right after a standard mag check, we would perform a “magneto ground check”, or ground check for short. It consisted of idling the engine and then cycling the mags completely off and then back on rapidly and listening to the engine to see whether or not it was shutting down or not. This was done as a safety measure by making sure the magneto P-leads were not broken. I maybe remember this wrong, but I think we performed this check again just before shutting down the engine at the end of the flight. The thing is, through years of watching You Tube flight videos have never heard any one do a Magneto Ground Check as a part of a standard check list procedure. Like your comments on this. Thanks.
Hi Allen, sorry for the long delay - somehow I missed your comment when you first posted it. I do the check you described (to detect a broken P lead) every now and then. I know pilots who do this at the end of each flight. I couldn't tell you why this is not in most POH checklists. Regards, Martin
Would it make sense to do the check during the flight before an oil change? It would be most likely conducted about every 50 hours close to your home airport and with the cowling coming off anyway.
Hi Martin. Thank you for the detailed explanation on how to recover if you have a problem. I do a LOP mag check regularly, and the information in your video will come in handy if that test ever detects a significant problem. I do have one question: to restart the engine, do you just turn the mags to both or do you have to engage the starter like you do on the ground to start the engine? Thanks for a great video.
No need to engage the starter - the propeller will be windmilling, so the engine is cranking all along, even when it doesn't make power. Regards, Martin
Boy I tell yuh, as a non-pilot, it takes extreme confidence in your equipment to turn off the ignition in flight. Well done Martin. It reminds me, as teenagers, we used to turn off the ignition on our cars and motorcycles going down the road then turn it back on after a few seconds for the bang effect in the exhaust....good stuff.
a dumb question... if you do find an issue with one mag, does it make more sense to leave key to other/healthy mag position (not both) after recovery for the rest of flight?
Good question. I guess there could be some rare failure modes where something other than the BOTH position is best for the remainder of the flight, including a failure in the switch itself. However, I would argue in most cases you are better off with as many plugs firing as you can get, and the most likely setting to get there is BOTH. - Martin
Another trick i use (apart from a chocolate cake thankyou to my tower guys after I got my IFR ticket) is to slowly over lean on each and then both mags till clear roughness...2-3 cycles. Then i download the data to Savvy’s free app, and look at the chart plots to see if anything anomalous is going on. Similarly with the in flight manifold check - i found a crack that way once that was making my start procedure take more and more rotations. Great video, and for sure the ground run up mag check is really...really a blunt instrument.
Martin, excellent insights and excellent advice. Thanks for the video. I will have to try this next time. Though it seems obvious in hindsight, it was very useful seeing the fuel flow remain the same with the mags off.
I guess we don't think much about fuel flow when the engine isn't making power, but it takes air, fuel, compression and a spark to run the engine - take any one away, and there's no power. - Martin
My mechanic has gone up with me to do in flight mag checks (O-360 so not LOP) while troubleshooting an issue. Sure is nice to have someone with you to show you how since there is some pucker factor involved first time. Great vid again Martin. Thx.
Yes, I remember how nervous I was when I did my first LOP mag check - and there wasn't even a problem that time. Good idea to try it with an instructor or a mechanic (ideally one who is also a pilot) if that makes you more comfortable.
@@skidivr A carbureted 4 cylinder is challenging to run LOP. I hear it can be done if the gammi spread is small. I don’t have an engine monitor yet so am erring on the safe side. Did get an electronic ignition but want to be careful with my engine. Im able to run 25 rich of peak to get the economy and speed.
@@tomdewitt4148 thx. I’ll clarify that I run the engine smooth on the rich side. Whether my single egt is really 25 rop or not I cannot say but that’s what my gauge is reading.
Definitely a perspective that needs to be considered, maybe not adhered to, but at least considered. However, I do have one constructive criticism comment: I noticed when you did the mag check on the ground you selected the Left mag, Both, Right mag, then back to Both again. I learned, and over the past 43 years I have taught that the sequence should be Right mag first, back to Both, THEN Left mag. Using this sequence it prevents an inadvertent "one-click" back to what you "think" is Both, when in reality the key is only moved to the Left mag position. Given the right circumstances, that error can lead to catastrophic conclusions. You may have your reasons for doing it your way, and that is okay - if it works for you (every time!).
Good comment, Fred. We had an exchange on this over on Facebook, so I'll copy&paste the key messages from there to UA-cam here so viewers on UA-cam can see it easily: Martin: Thanks for the constructive comment, Fred. I certainly see a need to prevent taking off with anything other than BOTH. However, if I do it the way you suggest, doesn’t the same vulnerability exist, just at an earlier time in the sequence? Either way, I believe ultimately one needs to verify that the RPM goes up and the EGTs go back down when the key is assumed back in the BOTH position. Thanks again for your input. Fred: The use of EGT and RPM is a good redundancy; however not all planes have EGT indicators (or engine monitors) installed. The way I see it, making the last key movement from Left to Both reduces the risk of becoming distracted when turning the key from Right to what is thought to be "Both". Even so, nothing is 100% foolproof, and only vigilance in the use of a checklist is a potential way to mitigate that risk,. Which reminds me, I have never seen a checklist showing the sequence to be L, Both, R, Both. With that in mind, there it is likely a very good reason that checklists are written in the R, Both, L, Both sequence.
@@martinpauly Thanks so much, for including our FB conversations on your UA-cam posting. I really think you went above and beyond to show your audience both of our views on this subject. Above all, I think the more information that is made available to everyone, the better they can understand a subject. Again, thanks for your willingness to share.
Martin - I noticed that your % HP was at 70% while you were running LOP - sometime I thought it was better to run LOP at 65% or lower - I have used the LOP mag check in flight but was never aware of how to recover from the possible accumulation of fuel with a dead spark plug - thank for the very simple but clear methods. V35B with IO520 here
Bill, you can run LOP at 70% or even higher power settings if you like; however, the famous "red box" is larger then. At 65% power or less, there really isn't a red box, and you can set the mixture any way you like without harming the engine. At 70% power, I recommend to be 20 degrees LOP, and even further LOP (80 to 100 degrees) at very high power. - Martin
Hello Martin from Sydney, Australia. Firstly, thank you for this explanation. I now have a better understanding of the ignition system and piston combustion engine used in small planes. Continential and Lycoming specifications. With LCD screen and measurements from the sensor, the PIC can identify beyond carburettor icing. * you said operating lean of peak may take a stronger spark. Do you suggest better plugs, leads or Bendix v Slicks magnetos? * Considering the power arch statistical graph (Savvy Aviation), each side for rich to lean of peak: air/fuel ratio, exceeding 400 °f and photos show, more pitting is done to piston, cylinder heads, and valve seals which (after a borescope inspection) could lead to a top overhaul: the last thing... a plane owner wants. Simply that's time and money. 🤔👨🍳 Happy Easter Captain.
I don't have a recommendation for specific mags or plugs. They just have to be working, John. They all can do the job when they are in good condition. - Martin
This, my friends is an AWFUL, dangerous idea. Go back and listen “only do this when I’m descending to an airport. When (not if) the engine stops or has partial power or worse yet, and inflight fire from unburned fuel, there is no way to make the airport. Come one folks, do not encourage this type of information.
martin- very educational (as usual) two things - 1. is there any reason not to set cruise egt's / cht's during ground run up and then do mag check? p-lead check? with the egts / chts at cruise temps wouldn't that accomplish the same thing/? 2. i saw where you mounted your ram mount on the large portion of the throw over yoke - have you had any issues with that location - i have a single yoke as well and was trying to find a good mounting point -- didn't think the hose clamp would go around the base of the yoke- thx
@@martinpauly In 1987 I began my airline career retiring in in 2014 so I have not flown a lot of piston engine airplanes. I had never heard of a mag check at altitude and lean of peak. I learned a valuable lesson from your video. Thanks for sharing it.
Please pull this video down, it suggests very very very unsafe "techniques" This is extremely dangerous and has little or no benefit to anyone. Unless this is in an emergency checklist inside an FAA approved POH, then this is just unsafe and unprofessional. If anyone has viewed this video, I implore you NOT TO DO THIS!!!!!!! Normal FAA POH ground testing along with your annual inspection is the only thing that follows true FAA procedures. What you are suggesting here is pure technique and a very poor and dangerous one at that. Other people might jump off a bridge, that doesn't me you have to, and suggest others do this also. While I have your attention, please do shoot videos while you are taxing on a active taxiway. Runway incursions can be deadly, you might kill someone else, not just yourself.
Is there a risk of thermal shock doing this in cruise, going from cruise power to no power and with cruise speed air cooling flowing through the engine nacelle
Martin; my mechanic advises against LOP operation in my non-turbo Lyc IO-360 (200 hp). His basis is that the benefit of a slightly better mpg is not worth the risk of potential increased engine stress. Perhaps on the higher power and fuel consuming engine as you have it might make economical sense but I already true at 140+ kts on 8.8 gph in the Arrow. I would be interested in your thoughts. Great video as always!
Check out Savvy Aviation leaning videos. He provides some great insights on optimal leaning for every type of engine and the mechanical advantages/disadvantages. Hope this will help!
Good morning Jim. To be blunt: your mechanic is wrong. Any standard digital engine monitor with probes for each cylinder will show you that an engine run LOP will be cooler (CHTs) than the same engine making the same horsepower ROP. And with special instrumentation on an engine test stand, it has been shown that the internal cylinder peak pressures are lower when LOP, too. So please ask your mechanic what is causing the "increased engine stress" - is it the lower pressures, or the lower temperatures? Rhetorical question, of course - it's neither. Surprisingly many pilots and mechanics are still convinced that LOP is the devil, just like some people are still convinced that the earth is flat. I am not saying LOP is always the best way to run the engine. But if your engine does indeed run smoothly LOP, you won't hurt it by doing so. Regarding "is it worth it"? While the Dollar savings are smaller than what I would see in my Bonanza, the efficiency and endurance/range benefit just as much. In the Cirrus SR20, we fly the Continental IO-360 LOP in cruise all the time, and it's the best way to get good range and keep the engine temperature low. Best regards, Martin
Martin and Dayton are absolutely right. The YT videos by Mike Busch of Savvy Aviation are briliant to learn about this topic. And LOP is actually better in many ways for an engine, provided that the injectors are relatively well balanced. I fly my E Mooney with a IO-360 LOP for ever with 7.5 Gph at 145KTAS and the engine is running with factoy injectors, not specially tuned GAMIs. I can achieve a little more TAS (about 155KTAS) with a lot more fuel (9.5-10.5Gph), which is just not worth the money, especially here in Europe, where the Galon AVGAS costs between 8 and 11 USD.
@@martinpauly Hi Martin, Thanks for the reply. I have a JPI 830 so running LOP will be straightforward to do. I will brush up on the procedure and give it a try! Your explanation is certainly logical and perhaps my mech's position is based on not being able to precisely adjust the mixture for LOP in airplanes before such EIS equipment. Jim
@@jimtorley70 Jim, a possible reason for the common misconception that the engine runs hotter LOP is that when first leaning from ROP, the temperatures do indeed go up. But as you cross peak EGT and lean further, temps will go down noticeably. I.e. it can be a problem to run somewhat lean but not lean enough. Regards, Martin
It's a bit debated how big a problem shock cooling really is, TJ. But let's assume for a second that it IS a problem. You have a few things going for you: (1) You've been flying LOP, so your cylinders are already cooler than they could be in ROP (2) The probability that a significant concern is identified when running on one mag is small (3) The recovery procedure is very short - only a few seconds. The engine will barely cool down during such a short time. (4) Consider the alternative - damage to your exhaust This just isn't the same as descending 12,000 feet in a hurry after dropping off skydivers, and doing it multiple times a day, day after day. Regards, Martin
I’ve never heard of an in-flight mag-check; ROP or LOP; fascinating. Further, tower controllers are apparently running Lean Of Pastry almost constantly, no matter how frequently they “windmill” about it. 😜✈️😎👍
LOP = Lean of Pastries. I hadn't thought about this, Mike. It's brilliant! 😁
- Martin
Haha brilliant!
Great timing! I watched Mike Busch's recent EAA webinar on mag failures and he discussed this very procedure. Your video is much more informative with regard to actually doing the check and the possible problems encountered.
Thanks, Bryce. I really wanted to show how this all works in real life - looks like I succeeded.
- Martin
Very well explained. I may add that the extra variable is altitude - the higher you are, the more demanding the test is on an ignition system due to reduced air pressure. The distributor in our mag relies on jump gap inside the cap to deliver the spark to each cylinder and jumping the gap for electricity diminishes with reduction in air pressure (hence the turbo planes have pressurized mags). Therefore, I tend to do this at higher altitudes to really stress test the system. If you fly a turbo engine, doing this test at altitude will also check that your mags are properly pressurized.
Good addition, Bart. Thank you!
- Martin
I'll admit it, Martin. That did look a little scary. But your explanation was, as always, thorough, informative and entertaining. Thanks so much!
Thanks, Jeff. Remember, shutting down the engine isn't part of the normal LOP mag check. It is merely the recover from an unlikely bad issue you might find while running the check, which in most cases is no more fearsome as the mag check on the ground.
Best regards,
Martin
Great video Martin... I flew one time with someone who did an inflight mag check LOP when I first bought Lola, but didn’t understand why. Thanks for this.
Thanks, Dan - glad I could help with connecting the dots on this topic.
- Martin
Thank you for not posting this yesterday. I wouldn't have known how to interpret it.
Are you thinking of an April fool's joke, or what was special about yesterday?
Thanks,
Martin
Yes, I would have watched it with added April Fool's Joke skepticism. 🤔
I did this yesterday on my Cherokee 235. I installed two new slick mags in April so wasn’t concerned if my mags were bad but thought it would be a good idea to check the system as a whole. I was LOP, put my EDM-830 into normalize mode and when I switched to the left mag and the EGT,s shot up to about 1700. The right mag check was a normal increase. I suspect the timing is off on the left mag?
Hi Tyler, sorry for the long delay in responding - I just now saw your question. Mag timing could explain what you observed, but I would not rule out other explanations. Have you had a chance since then to investigate further?
Regards,
Martin
Just lean it on the ground and check it there. There’s absolutely no reason to be turning off any part of an operating system in flight, unless it’s a failure and part of a published checklist.
Chris, I think I was pretty clear about what the reason is in this video. You are right of course to weigh the risks against the benefits in a given situation - say, while over the middle of Lake Michigan, vs. over an airport with a nice, paved runway - and in some cases I would agree you should save this check for another flight or another time. But simply saying "there is no reason" is not something I agree with.
- Martin
Heh - I once had this problem with an old, beyond-retirement U-Haul truck. The coil wire was loose, so it was firing intermittently, and it sounded like I was lighting firecrackers the whole trip.
So it appears the only difference of doing this more sensitive check in the air and on the ground is (a) more power and (b) leaner mixture. Could you still get more proactive results as you explain in the ground check by adding power and/or leaning the mixture then doing magneto checks? Either way, I'm apt to try the experiment with the criticals of recovery procedure in mind!
In theory, I guess - but I would not want to do a ground run-up like this on a regular basis. I feel bad enough for my prop at 1,700 RPM; running at 60% power or so and then taking the time to lean precisely to an appropriate cruise mixture with the brakes locked on the run-up pad - that's not something I like to do to my airplane.
Regards,
Martin
Am I correct in inferring that this would also potentially indicate a problem with a spark plug? I am also trying to figure out what about the mag itself would cause one plug/cylinder to not ignite properly - presumably the mag not producing enough voltage and/or power(amps) to trigger the spark on the most resistive plug/cylinder. Yet another indication that I need to learn more about how mags actually work!
Yes, Thomas, a bad spark plug is one of the possible contributors to an ignition system problem. It could also be a magneto, or the ignition harness (wiring), or the ignition switch.
Regards,
Martin
This makes sense if the goal is to maximize up time. But if the goal is to reduce risk of in-flight engine issues, this seems to add risk rather than reduce it.
And what risk would that be? That the engine stops making power on one mag? Yes, that is a possibility, but it'll immediately come back alive when turning to both mags. And at least then you KNOW there is a problem, I prefer that over continuing the flight without any clue that I have a mag issue.
Regards,
Martin
Oh I bet my wife would love that! Honey, gotta turn of the engine for a few....😂
Patrick, an alternative solution is to pull the throttle back to idle power without first pulling the mixture. Then turn MAGS to BOTH, and reapply power. This still provides some protection for your exhaust (vs. restoring ignition at full cruise power).
- Martin
I see the internet keyboard warriors having a field day with this one. :)
Some of them are already on their mission. 😁
- Martin
That was great, Martin!
I have been told that it's good to get 10 or 20 "samples" into your engine monitor logs when doing this test. I believe my JPI 800 is set for 2 seconds (the min), so I wait for 20-30 seconds on each mag.
When you upload the file to Savvy Analysis, there is a "Mag Check" button (the "M" in the circle) which changes both plots to be EGT and puts the odd cylinders on top and even cylinders on bottom. This can really help point out if there is a problem developing - even if all 6 keep firing as they should thru the test.
The other comment about all mag checks (ground or LOP in air) I would add is this: I "normalize" my engine monitor before the check. I then look for all 6 to rise together when on each mag. I think your display (the 930) has better resolution so it does not matter.
I will say that one way an engine monitor pays for itself is when you do a mag check and one EGT bar goes to 0. It's so great to know the exact cylinder and spark plug that stopped firing. That alone probably saves an hour time knowing exactly where to start looking for issues.
Thanks for the additional insight, Jim - that's a good addition. Yes, I have played with this feature on the Savvy website, and I agree it can be a useful tool.
Best regards,
Martin
You can still blow an exhaust up on the ground. If you hit off on a mag check on ground. Let it die. Then restart.
Hi Gabe. You may be right, but I have not heard of this. Mag issues happen somewhat regularly, and I bet when they do, most pilots don't shut down but simply go back to BOTH. So one would expect that we hear about exhaust damage from a failed ground run-up every now and then - and I just don't remember ever hearing about it.
Kind regards,
Martin
@@martinpauly I find split mufflers fairly often or bulged mufflers on flight training aircraft for said mag switch mistake. I do wonder what its going to be like with a surefly on my Mooney. Doing install right now.
Great video Martin as always and thanks for having the guts not only to turn off both mags in flight to make your point, but also posting it for the benefit of the community (knowing you would get some people objecting to that). A question: You said LOP and WOT. How would this test work at a lower altitude with reduced throttle? To be clear, not that I would really do this test at low altitude but just curious about the implications of doing it with lower MP at lower altitude (still LOP)?
Excellent thx
I want to start testing the mags LOP as you explain for a while, will do next flight. But this bring up a question. What about doing the LOP test on the ground like a regular runup?
Martin , you should team up with Mike Busch , you both know how to transfer your aviation wisdom except your videos creating great real time experience . LOP was excellent as well .
TY .
Thanks Martin, I’ll add this to my CFI tool bag because I had never thought of it before nor heard of it. Thanks!!
Great video! Great way to show how the world does not stop just because either spark or fuel is interrupted during a normal flight. This would be a great emergency procedure to practice to understand the relation between airspeed, engine speed, manifold, and RPM with the absence of power. Thanks again for your commitment to great power and engine management and the relation between them both! Us here in Oregon would love some pastries! Great out takes! Thanks again, Martin!
Thanks, Kyle. You are right, there is a lot of uncertainty over what happens if or when the engine stops making power. In most cases, the airplane simply turns into a glider, but the laws of physics and aerodynamics still apply. And restarting a piston engine in flight isn't a big deal - fuel, air, compression, and spark, and we are in business.
- Martin
Very nice work! Impressive. So clear, concise and really great to watch it applied during an actual flight. I hope you do more on engine analyzer interpretations...isolating bad spark plugs, catching clogged injectors, etc.
Thanks for the kind words, Michael. Yes, I do plan to create more videos on engine management in the future.
- Martin
Fuel flow still normal. Brilliant. Washed your cylinder walls down and blew wet fuel out the exhaust. BRILLIANT.
Besides the fact that this isn't the normal, expected outcome of the ignition test - may I ask what alternative you suggest instead?
FYI: the air-to-fuel mixture in a reciprocating combustion engine is 14.7:1. And that's a weight ratio, not a volume one. It's an aerosol more than anything else. No "washing down" of anything.
So... why do we need to do it in flight? Can't we use cruise power and lean mixture on the ground?
Very good video Martin!
Thank you, Chris.
- Martin
informative video. I will probably will never be a pilot. I still love the knowledge. great video
Thank you, David - glad you found this one interesting.
- Martin
Martin, This was a great demo! Most of us have experienced the hot start in fuel injected engines, where it may be very difficult to start a hot engine due to the fuel vapor in the lines. I would be extremely worried about having a hard time restarting the engine after shutting it down. Or, does the fact that you're airborne, with lots of cooling air flowing over the engine make it very easy to restart without the usual hot engine starting fuss? My Piper Lance can be a real bear to restart if it's hot.
Good question, Eric. I have experienced the dreaded hot start many times in various aircraft. There are three reasons why this is not a concern when doing a restart in air:
(1) Your propeller is windmilling, giving your engine better compression and your magnetos more power for the spark plugs than your starter motor is able to provide.
(2) When in air, there is a lot of air coming in to cool the engine, to the point where the worry isn't "hot start" but "excessive engine cooling". Certainly the cooling air coming into your engine compartment will prevent vapor locks from building.
(3) Typical hot starts end up being difficult because, in an effort to overcome the vapor locks, pilots end up with a flooded engine. When restarting in air, the engine will restart the moment you push the mixture knob far enough forward to have a combustible fuel/air mixture.
Still if you are worried, you may want to recover by only pulling the throttle back, not the mixture. If you reduce power to a minimum, you will likely not harm your exhaust when the the ignition system is restored to full operation.
Regards,
Martin
@@martinpauly Martin, Thank very much for that, it makes perfect sense! I will definitely go through the procedure.
Another educational video for us Bonanza owner/operators. Well done.
Thanks, Jim. Just want to add that this applies not just to Bonanzas.
- Martin
Now I'm running LOP (Lean Of Pastry)!! 8) Just curious, have you vetted that procedure before putting it out here? I only ask because I don't recall seeing it done before. It looks very valuable for early diagnosis. Thanks!! JMHO --gary
In-flight LOP mag checks have been recommended for years by people who understand aircraft piston engines a lot better than I do. Mike Busch, John Deakin, and the APS (Advanced Pilot Seminar) crew. I did not invent anything new, I merely put it into tutorial format.
- Martin
It is quite informative, even for pilots like myself. Thanks.
Interesting video... we run a Lycoming O-360 in our Grumman AA-5B. Although there's nothing in the POH that mentions being able to run LOP, many experienced Grumman owners know that running LOP is not an option in a Tiger. The engine just complains a lot when trying to set LOP. It seems carbureted engines tend not to like running in that mode.
This video is a bit timely... a few weeks ago, my son and I were flying our Grumman on a beautiful, severely clear VFR day to go do some practice instrument approaches up at the Cheyenne airport, about a 30 minute flight from our home airport. As we got to our assigned cruise altitude of 8,000', I noticed the engine running a bit rougher than normal. Since it was quite chilly outside, I suspected possible carb ice, so I applied carb heat. As I went through the normal leaning procedure for cruise, we both noticed that the engine still would not run smoothly. RPM was indicating normal and all gauges were "in the green", but something still didn't feel right. EGTs and CHTs were also reading differently. The number one EGT and CHT was reporting "cooler" than normal. I asked my son what he thought and he confirmed my suspicion. The engine was not running normally.
We cancelled IFR and declared an emergency so that we could have priority getting back to our home airport. We asked if we could enter the Denver Class Bravo at 8,000' so that we could have plenty of altitude in case the engine quit. 6,500' is pattern altitude at our home airport. ATC was quick to clear us in unrestricted. We landed without incident, but were greeted by a plethora of fire equipment as we exited the runway.
Anyway, upon inspection of the engine via a compression check, we found that the exhaust valve in the number one cylinder was sticking open. We've since taken the cylinder off to have it serviced. I'm hoping to get my airplane put back together soon, so we can enjoy the upcoming spring weather. Thanks again for putting this video together.
Fly safe and fly often!
PS - If you're ever in Denver at KBJC, look us up... we LOVE fresh pastries!
Hi Gordon, glad to hear your emergency had a good outcome. Many (maybe most?) engine failures result in partial power, not a complete power loss. There may be a LOT of roughness, but at least you can fly to an airport and land.
- Martin
Very informative video and well explained! Taking about fuel igniting in the exhaust... I think everybody who has owned a motorbike with a straight through pipe has at least once turned the ignition off while riding with the throttle wide open, left it for a few seconds and then turned it back to enjoy the nice bang and sometimes flash out the back 😂 Great in tunnels 😎
More than one aircraft exhaust has been broken in the process of doing this 😁
- Martin
Thanks Martin! Your videos are so helpful from a technical standpoint! Keep on posting! I’m a new 182 owner and I value your wisdom to help me manage my airplane! (But I’m still a ROP guy… we’ll see!).
Resist the temptation to make your videos more fancy with music, pretty girls, and exotic destinations! All we care about is how to be the best pilot possible!!!
Thanks for the kind feedback, JD, and maybe you'll try LOP one of these days in your Skylane!
(Hint: It's not about damaging your engine or not, and more about whether your engine will get to the lean side of peak before it runs rough. If it does get there, there's no harm.)
Regards,
Martin
Very interesting video Martin. I watch your videos often, but came across this one via a search I made, namely “magneto ground check”. Now, I’m an old timer who can no longer fly except vicariously through young, You Tube whippersnappers like you. My father owned a flight school/charter operation in the Seattle area from the early 50’s through the mid 70’s.
Now, to the point. If I remember right, as a part of our engine run up, maybe right after a standard mag check, we would perform a “magneto ground check”, or ground check for short. It consisted of idling the engine and then cycling the mags completely off and then back on rapidly and listening to the engine to see whether or not it was shutting down or not. This was done as a safety measure by making sure the magneto P-leads were not broken. I maybe remember this wrong, but I think we performed this check again just before shutting down the engine at the end of the flight.
The thing is, through years of watching You Tube flight videos have never heard any one do a Magneto Ground Check as a part of a standard check list procedure.
Like your comments on this. Thanks.
Hi Allen, sorry for the long delay - somehow I missed your comment when you first posted it.
I do the check you described (to detect a broken P lead) every now and then. I know pilots who do this at the end of each flight. I couldn't tell you why this is not in most POH checklists.
Regards,
Martin
Would it make sense to do the check during the flight before an oil change? It would be most likely conducted about every 50 hours close to your home airport and with the cowling coming off anyway.
I run it a little more often than that, but I agree before the oil change is a good time, for the reasons you mentioned.
- Martin
Hi Martin. Thank you for the detailed explanation on how to recover if you have a problem. I do a LOP mag check regularly, and the information in your video will come in handy if that test ever detects a significant problem. I do have one question: to restart the engine, do you just turn the mags to both or do you have to engage the starter like you do on the ground to start the engine? Thanks for a great video.
No need to engage the starter - the propeller will be windmilling, so the engine is cranking all along, even when it doesn't make power.
Regards,
Martin
Boy I tell yuh, as a non-pilot, it takes extreme confidence in your equipment to turn off the ignition in flight. Well done Martin. It reminds me, as teenagers, we used to turn off the ignition on our cars and motorcycles going down the road then turn it back on after a few seconds for the bang effect in the exhaust....good stuff.
Heh. In my car it sounded like a gunshot. Back then this wasn't that big of a deal; I'd worry today about ending up in a jail cell or dead.
a dumb question... if you do find an issue with one mag, does it make more sense to leave key to other/healthy mag position (not both) after recovery for the rest of flight?
Good question. I guess there could be some rare failure modes where something other than the BOTH position is best for the remainder of the flight, including a failure in the switch itself. However, I would argue in most cases you are better off with as many plugs firing as you can get, and the most likely setting to get there is BOTH.
- Martin
Another trick i use (apart from a chocolate cake thankyou to my tower guys after I got my IFR ticket) is to slowly over lean on each and then both mags till clear roughness...2-3 cycles. Then i download the data to Savvy’s free app, and look at the chart plots to see if anything anomalous is going on. Similarly with the in flight manifold check - i found a crack that way once that was making my start procedure take more and more rotations. Great video, and for sure the ground run up mag check is really...really a blunt instrument.
The Savvy analysis/viewer for engine data is a very good tool for this, yes.
- Martin
'I hope this last part didn't scare you'. CODE BROWN, CODE BROWN! it did.
Sorry - I hope it wasn't too bad! 😁
- Martin
Great video. Complies with my habit to ABL (Always Be Learning). Happy Easter.
ABL - that's a good attitude for any pilot! 👍
- Martin
Risky for inexperienced pilot lols 😂
I've never heard of this, Martin. Excellent explanation of something very important. Thank you!
Thanks, John.
- Martin
Martin, excellent insights and excellent advice. Thanks for the video. I will have to try this next time. Though it seems obvious in hindsight, it was very useful seeing the fuel flow remain the same with the mags off.
I guess we don't think much about fuel flow when the engine isn't making power, but it takes air, fuel, compression and a spark to run the engine - take any one away, and there's no power.
- Martin
My mechanic has gone up with me to do in flight mag checks (O-360 so not LOP) while troubleshooting an issue. Sure is nice to have someone with you to show you how since there is some pucker factor involved first time. Great vid again Martin. Thx.
Yes, I remember how nervous I was when I did my first LOP mag check - and there wasn't even a problem that time. Good idea to try it with an instructor or a mechanic (ideally one who is also a pilot) if that makes you more comfortable.
Why not LOP?
@@skidivr A carbureted 4 cylinder is challenging to run LOP. I hear it can be done if the gammi spread is small. I don’t have an engine monitor yet so am erring on the safe side. Did get an electronic ignition but want to be careful with my engine. Im able to run 25 rich of peak to get the economy and speed.
@@BlessedtoFly 25 ROP is not a good place to be.
@@tomdewitt4148 thx. I’ll clarify that I run the engine smooth on the rich side. Whether my single egt is really 25 rop or not I cannot say but that’s what my gauge is reading.
Gotta love the pastry call outs in the out takes!
We got some perpetually hungry controllers here at KCID 😁
- Martin
Definitely a perspective that needs to be considered, maybe not adhered to, but at least considered. However, I do have one constructive criticism comment: I noticed when you did the mag check on the ground you selected the Left mag, Both, Right mag, then back to Both again. I learned, and over the past 43 years I have taught that the sequence should be Right mag first, back to Both, THEN Left mag. Using this sequence it prevents an inadvertent "one-click" back to what you "think" is Both, when in reality the key is only moved to the Left mag position. Given the right circumstances, that error can lead to catastrophic conclusions. You may have your reasons for doing it your way, and that is okay - if it works for you (every time!).
Good comment, Fred. We had an exchange on this over on Facebook, so I'll copy&paste the key messages from there to UA-cam here so viewers on UA-cam can see it easily:
Martin:
Thanks for the constructive comment, Fred. I certainly see a need to prevent taking off with anything other than BOTH. However, if I do it the way you suggest, doesn’t the same vulnerability exist, just at an earlier time in the sequence? Either way, I believe ultimately one needs to verify that the RPM goes up and the EGTs go back down when the key is assumed back in the BOTH position.
Thanks again for your input.
Fred:
The use of EGT and RPM is a good redundancy; however not all planes have EGT indicators (or engine monitors) installed. The way I see it, making the last key movement from Left to Both reduces the risk of becoming distracted when turning the key from Right to what is thought to be "Both". Even so, nothing is 100% foolproof, and only vigilance in the use of a checklist is a potential way to mitigate that risk,. Which reminds me, I have never seen a checklist showing the sequence to be L, Both, R, Both. With that in mind, there it is likely a very good reason that checklists are written in the R, Both, L, Both sequence.
@@martinpauly Thanks so much, for including our FB conversations on your UA-cam posting. I really think you went above and beyond to show your audience both of our views on this subject. Above all, I think the more information that is made available to everyone, the better they can understand a subject. Again, thanks for your willingness to share.
Exceptional! Top notch professional grade presentation. Kudos!
Thank you!
- Martin
Thanks, have leaned to rough engine to clear fouled spark plug that works most of the time but not that. Thanks.
Thanks, Ed - yes, that's another thing where aggressive leaning can help.
- Martin
Martin - I noticed that your % HP was at 70% while you were running LOP - sometime I thought it was better to run LOP at 65% or lower - I have used the LOP mag check in flight but was never aware of how to recover from the possible accumulation of fuel with a dead spark plug - thank for the very simple but clear methods. V35B with IO520 here
Bill, you can run LOP at 70% or even higher power settings if you like; however, the famous "red box" is larger then. At 65% power or less, there really isn't a red box, and you can set the mixture any way you like without harming the engine. At 70% power, I recommend to be 20 degrees LOP, and even further LOP (80 to 100 degrees) at very high power.
- Martin
@@martinpauly thanks Martin - time to experiment some!
Hello Martin from Sydney, Australia.
Firstly, thank you for this explanation. I now have a better understanding of the ignition system and piston combustion engine used in small planes.
Continential and Lycoming specifications.
With LCD screen and measurements from the sensor, the PIC can identify beyond carburettor icing.
* you said operating lean of peak may take a stronger spark. Do you suggest better plugs, leads or Bendix v Slicks magnetos?
* Considering the power arch statistical graph (Savvy Aviation), each side for rich to lean of peak: air/fuel ratio, exceeding 400 °f and photos show, more pitting is done to piston, cylinder heads, and valve seals which (after a borescope inspection) could lead to a top overhaul: the last thing... a plane owner wants. Simply that's time and money.
🤔👨🍳 Happy Easter Captain.
I don't have a recommendation for specific mags or plugs. They just have to be working, John. They all can do the job when they are in good condition.
- Martin
@@martinpauly Thank you, sir.
Great content Martin. Have done in flight mag checks but not LOP
Thanks, Steve.
- Martin
Good, but time for a turbine Mr Martin , to much LOP & ROP :(
Time for a turbine? I just checked my wallet, it says "no", I'm afraid. But one can dream!
- Martin
( ) Nice To Know
( ) Good To Know
( ) Need To Know
(X) All The Above
👍🏻👍🏻👍🏻
This, my friends is an AWFUL, dangerous idea. Go back and listen “only do this when I’m descending to an airport. When (not if) the engine stops or has partial power or worse yet, and inflight fire from unburned fuel, there is no way to make the airport. Come one folks, do not encourage this type of information.
Very interesting check. Thank you for sharing it with us.
My pleasure!
- Martin
martin- very educational (as usual) two things - 1. is there any reason not to set cruise egt's / cht's during ground run up and then do mag check? p-lead check? with the egts / chts at cruise temps wouldn't that accomplish the same thing/? 2. i saw where you mounted your ram mount on the large portion of the throw over yoke - have you had any issues with that location - i have a single yoke as well and was trying to find a good mounting point -- didn't think the hose clamp would go around the base of the yoke- thx
That shutdown procedure I would imagine would have an added benefit of cleaning the exhaust valves and ports a bit from the raw fuel wash. 👍
Thanks a lot for the informative video and, the making, i like the friendly relation between you and the twoer, great work.
My pleasure!
- Martin
@@martinpauly 🌷🌷
Great insights, and good to see what actually happens when turning off the ignition, and how to safely restart in flight.
Hi Martin, awesome info, as always packed into an entertaining video! Safe landings! Greetings from Germany
Interesting!
Thanks Martin!
You are welcome, Nick!
- Martin
Thanks Martin for the new knowledge
Thanks, Brian.
- Martin
this was a new information for me, thanks Martin
You are welcome, Wael.
- Martin
Great info, thank for another one.
You are welcome!
Great info. I had never heard of this.
How about bringing some pastries to Ohio?
How about coming to another Third Thursday in MCW, and then you and I can fly to Pella together and get a big box to share at the BBQ?
- Martin
@@martinpauly I am hoping to make it over there for the one in May. I'll be at a fly in for PA32s in Memphis in April.
@@jonathanchristman8488 May will likely be my next one as well - I'll be in Lakeland for the one in April.
@@martinpauly I am going to have to pass on Sun N Fun this year. Too much to do and too little time...lol
Great advice
Thank you, James.
- Martin
@@martinpauly In 1987 I began my airline career retiring in in 2014 so I have not flown a lot of piston engine airplanes. I had never heard of a mag check at altitude and lean of peak. I learned a valuable lesson from your video. Thanks for sharing it.
Please pull this video down, it suggests very very very unsafe "techniques" This is extremely dangerous and has little or no benefit to anyone. Unless this is in an emergency checklist inside an FAA approved POH, then this is just unsafe and unprofessional. If anyone has viewed this video, I implore you NOT TO DO THIS!!!!!!! Normal FAA POH ground testing along with your annual inspection is the only thing that follows true FAA procedures. What you are suggesting here is pure technique and a very poor and dangerous one at that. Other people might jump off a bridge, that doesn't me you have to, and suggest others do this also.
While I have your attention, please do shoot videos while you are taxing on a active taxiway. Runway incursions can be deadly, you might kill someone else, not just yourself.
Is it in the POH? I think not...... foolish procedure.
Is there a risk of thermal shock doing this in cruise, going from cruise power to no power and with cruise speed air cooling flowing through the engine nacelle
That is so straightforward and to the point it should be made part of an annual if not the quintessential 100 hr inspection.
Thanks, Norbert. Good idea to do this check right before an annual or 100hr inspection.
- Martin
Martin; my mechanic advises against LOP operation in my non-turbo Lyc IO-360 (200 hp). His basis is that the benefit of a slightly better mpg is not worth the risk of potential increased engine stress. Perhaps on the higher power and fuel consuming engine as you have it might make economical sense but I already true at 140+ kts on 8.8 gph in the Arrow. I would be interested in your thoughts. Great video as always!
Check out Savvy Aviation leaning videos. He provides some great insights on optimal leaning for every type of engine and the mechanical advantages/disadvantages. Hope this will help!
Good morning Jim. To be blunt: your mechanic is wrong. Any standard digital engine monitor with probes for each cylinder will show you that an engine run LOP will be cooler (CHTs) than the same engine making the same horsepower ROP. And with special instrumentation on an engine test stand, it has been shown that the internal cylinder peak pressures are lower when LOP, too. So please ask your mechanic what is causing the "increased engine stress" - is it the lower pressures, or the lower temperatures? Rhetorical question, of course - it's neither. Surprisingly many pilots and mechanics are still convinced that LOP is the devil, just like some people are still convinced that the earth is flat. I am not saying LOP is always the best way to run the engine. But if your engine does indeed run smoothly LOP, you won't hurt it by doing so.
Regarding "is it worth it"? While the Dollar savings are smaller than what I would see in my Bonanza, the efficiency and endurance/range benefit just as much. In the Cirrus SR20, we fly the Continental IO-360 LOP in cruise all the time, and it's the best way to get good range and keep the engine temperature low.
Best regards,
Martin
Martin and Dayton are absolutely right. The YT videos by Mike Busch of Savvy Aviation are briliant to learn about this topic. And LOP is actually better in many ways for an engine, provided that the injectors are relatively well balanced. I fly my E Mooney with a IO-360 LOP for ever with 7.5 Gph at 145KTAS and the engine is running with factoy injectors, not specially tuned GAMIs. I can achieve a little more TAS (about 155KTAS) with a lot more fuel (9.5-10.5Gph), which is just not worth the money, especially here in Europe, where the Galon AVGAS costs between 8 and 11 USD.
@@martinpauly Hi Martin,
Thanks for the reply. I have a JPI 830 so running LOP will be straightforward to do. I will brush up on the procedure and give it a try! Your explanation is certainly logical and perhaps my mech's position is based on not being able to precisely adjust the mixture for LOP in airplanes before such EIS equipment.
Jim
@@jimtorley70 Jim, a possible reason for the common misconception that the engine runs hotter LOP is that when first leaning from ROP, the temperatures do indeed go up. But as you cross peak EGT and lean further, temps will go down noticeably. I.e. it can be a problem to run somewhat lean but not lean enough.
Regards,
Martin
What about shock cooling?
It's a bit debated how big a problem shock cooling really is, TJ. But let's assume for a second that it IS a problem. You have a few things going for you:
(1) You've been flying LOP, so your cylinders are already cooler than they could be in ROP
(2) The probability that a significant concern is identified when running on one mag is small
(3) The recovery procedure is very short - only a few seconds. The engine will barely cool down during such a short time.
(4) Consider the alternative - damage to your exhaust
This just isn't the same as descending 12,000 feet in a hurry after dropping off skydivers, and doing it multiple times a day, day after day.
Regards,
Martin