YTread Logo
YTread Logo

All About Magnetos

Jun 02, 2021
Ok, thank you very much, hello everyone, happy new year, tonight's topic is about Magneto, what does it mean to do that and we have a lot of things to discuss, we are going to talk about the construction of Magneto, the various components, how they work together . We'll talk a little about common Magneto failure modes. I'll show you some ugly pictures. We will talk about magnetic synchronization. There are actually two different types of magnetic timing. Internal timing and external synchronization. We'll talk about how Magnetos are set up. Starting the engine is a particular problem with magneto ignition engines and there are two different approaches to getting a magneto ignition engine started, so we'll talk about that a little bit, we'll talk about magnetic checking.
all about magnetos
I am a strong opponent of both the pre-flight magnetic check and the in-flight magic switch. I talked a little bit about some unique issues we have with Magneto for aircraft operating at high altitudes, such as flight levels. I talk about the importance of 500. hour inspections on Magneto and we'll talk a little bit about the different makes and models of Magneto and compare the pros and cons of each and finally just a quick word on some troubleshooting procedures , so let's go ahead and talk about the different keys. magneto components this is an exploded diagram of a slick charger there are two main brands of Magneto slick chargers which are now made by Champion and Bendix chargers which are made by Continental and as you can see there are a lot of pieces and parts and let's talk a little of them about what they do and how they work together the heart of the magnet is the rotor, it may also be at some point also known as a rotating magnet assembly because it is a very, very strong permanent magnet mounted on a The shaft works with some bearings in the magneto case and the fact that it is a permanent magnet is why they call the device a magneto.
all about magnetos

More Interesting Facts About,

all about magnetos...

It spins it by a drive gear in the motor. It rotates the rotor at crankshaft speed for 4-cylinder engines and at one and a half times the crankshaft speed for 600 jhin, the rotor rotates within a coil assembly and, because it is a strong permanent magnet, as it rotates inside the coil assembly, induces an alternating current in that coil assembly, actually generates two pulses per revolution of the rotor one in each direction as the north pole passes through the pole pieces, then the south pole passes through the pieces polar, the amount of energy you generate in the coil, of course, is a function of how fast the rotor spins and also the strength of the magnet, these magnets retain their magnetism very, very well over time , when magnetic chargers are finally overhauled, one of the things that is done is the rotor is remagnified.
all about magnetos
The rotor spins inside a coil assembly. and this is what a coil assembly looks like, it is housed in a very sturdy epoxy box and has three connections, it has a ground wire which is the white wire on the left, it has a wire connected to the hot side of the primary coil It is the green wire on the right and it actually connects to the brake points and has a high voltage tab that is connected to the hot side of the secondary and that tab is actually connected to the Magneto distributor by means of a Carbon Brush which you'll see on a next slide, but you can see on that car on that high voltage tab, you can see the impression of the little carbon circle where the brush was on that high voltage tab, so that's what the coil looks like. and again it has three connections: a ground wire towards the hot side of the primary and a tab connected to the outside is Decker.
all about magnetos
The primary winding of the coil usually has about 200 turns of heavy gauge copper wire wound on a laminate. iron armature, one end is permanently grounded to that white wire which you can actually see is grounded directly to the Magneto box and the other end connects to that green wire that goes to the switch points, the secondary winding which also It is inside the coil assembly. about 20,000 turns a very, very fine copper wire. I think I did it wrong, it says 200 times increase, it should really read 100 times increase, but I rate any voltage induced in the primary increases a hundred times in the secondary and then the secondary outputs a very high voltage again, one end of the secondary winding is permanently grounded by that white wire which is grounded to the magneto case and the other end is connected to the high voltage tab that the carbon brush mounts on. the cam and breakpoint assembly the cam is on one end of the rotor shaft this particular image is of a slippery charger and you can see that the cam on a slippery charger is simply a piece of plastic that inserts into a slot on the rotor shaft so it has two lobes, plastic lobes sticking out one on each side and again the points will end up opening twice per revolution of the rotor on the TTM or Continental Bendix magazines, the cam is really honest.
God, metal cam with two lobes, it's made of metal instead of plastic, plastic is used in the slick magazines and you can also see the Broder or breakpoint assembly there for the tungsten contacts, one is connected to land permanently and the other. that's connected to that green wire to the primary coil so when the points are closed the primary the green wire is grounded and when the points are open the green wire is open and that connects anything and the cam opens the points once every half revolution of the rotor or twice per revolution the points are normally closed and when the points are closed the primary the two ends of the primary are connected to each other, both are connected to ground, so that when the magnet in the rotating rotor induces a current in that primary which flows continuously round and round through the primary winding of the coil which creates a powerful magnetic field in the coins in the coils rolled iron armature at the time of ignition of the cam opens the tips and breaks the loop which causes the magnetic field in the coil to suddenly collapse and the collapse of that field creates a voltage spike in the primary of two hundred to three hundred volts and induces a very high voltage spike in the secondary, typically of twenty to thirty thousand volts, sometimes there is a capacitor called a capacitor sometimes called a capacitor two different words for the same thing and it is connected across the switch points the purpose of the capacitor is to prevent arcing between the points as it open there is this very high voltage or relatively high voltage pulses of two hundred or three hundred volts that are induced in the primary and if it weren't for the capacitor that would cause arcing at the points as they start to open when the cam starts to open the points and would cause the points to sink and erode and wouldn't last long, so the capacitor absorbs that energy and as the points begin to open and prevent arcing through the points, so does the capacitor. provides a predictable collapse of the magnetic field that is not actually the case.
It is not very sensitive to the condition of the points, so if the points start to erode a little, the collapse of the field as the points open remains fairly constant and therefore the characteristics of the mag remain constant even when the points start to wear a little bit, but if the condenser goes bad as it happens from time to time and these things deteriorate over time and after six or seven years they can start to go bad and if the condenser goes bad then the points will form an arc and they will begin to pit quite a bit and that is one of the causes of magneto failure.
Here's a kind of ugly little schematic diagram that shows how these things come together. You have the primary that is connected to the points. There is a capacitor at the contact point or condenser to prevent arcing at those points, the secondary, this shows that it is connected directly to the hot terminal, the spark plug, in fact, actually passes through a distributor that connects it to the proper spark plug, proper spark plug. one of the four six spark plugs in the engine but this diagram for simplicity omits the distributor here is the distributor it is a plastic gear which is plastic because plastic does not conduct electricity and there is a real high voltage here and the gear turns in a bearing and an oil light bearing, bearing is permanently lubricated and has a copper finger that rotates and approaches one of the four or six contacts in the distributor block.
The finger doesn't actually touch the contacts, it just comes. very close to them and this is what is called a jump distributor, so there is actually no metal contact, but the finger gets close enough to the contacts that the high voltage pulse from the coil jumps across of that gap and goes to the appropriate spark plug, the distributor is geared down, so it rotates at half the speed of the crankshaft, so compared to the rotor, it is geared down by a factor of 2 if is a 4 barrel mag or by a factor of 3 if it is a 6 barrel mag. but the distributor always rotates at half the speed of the crankshaft, it takes credible chef rotations to put each of the cylinders in their four cycles, as I said, the rotating wiper attracted by the distributor gear passes very close to the electrodes of the distributor block close enough.
In order for the spark to jump that gap and proceed through the appropriate ignition wire to the spark plug and ignite the spark plug, it is extremely important that the inside of the distributor block be scrupulously clean because any contamination inside the charger can result in conductive contamination. path which can cause internal arcing inside the charger, all the internal arcing will cause Amélie to ignite, it will make the engine run very poorly, but secondly, it can cause things to heat up inside the charger to the point where the things start to melt. and then really bad things happen, one of the main failure modes we see in Magneto and, in fact, we've seen a really alarming number of them in recent years.
Our distributor gear failures. Here are some examples where the plastic distributor gear ends up losing a tooth or series of teeth and of course once it does the distributor just starts going crazy and fires the spark plugs at the wrong time and can do cause the engine to go crazy, now one of the reasons we have two Magnetos on. Each engine is so that if a failure like this occurs, we can turn off the magneto that is causing the problem and run the engine with the magneto that still helped help the health, but one of the things I have noticed with some alarm is that in the last In some years, in the end, just the fleet of airplanes that my company manages is several hundred airplanes that we have had.
Oh, something like half a dozen catastrophic magneto failures of this type, some of them at high altitude, some of them occurred in the pattern, some have occurred, I have for some, several of them have occurred with pilots or flight instructors extremely experienced flying the plane and in no case the pilot when the engine started running extremely abruptly or threatened to stall. In no case did the pilot have the presence of mind to try to shut down one Magra instead of the other to shut down the magnets gone crazy and run the individual magnets that are still working properly, so you know that having two chargers is good, but it doesn't help much unless the pilot turns off the faulty magazine when it starts doing strange things and it seems that pilots have the notion that the only type of magazine failure is one where the magazine simply stops working and stops firing, but that doesn't work. it's true.
The most common cause of charger failure is that we have been seeing problems in our distributor gear like this, where the charger keeps firing, it just fires the wrong plugs at the wrong time and causes the engine to do really horrible things and the solution The point is to figure out which charger is bad and turn it off, but for some reason most pilots just don't seem to have the presence of mind or the presence of a checklist or whatever to do that, so that's the answer. which is why I'm harping on This is another failure mode that we've seen specifically with slippery magazines and it actually got so bad that an ad appeared about failures where the carbon brush started to fail and spread carbon dust, conductive carbon dust on the inside of the magazine, the magazine then Arcs through these paths of carbon dust and starts melting things and you can see this is the main distributor gear bracket that has been totally destroyed by the arc inside the charger due to the deterioration of the carbon brush in this particular case.
It turned out that that blob had a bunch of faulty brushes and they were getting into the system and they were starting to deteriorate at a rapid rate and wreaking havoc inside the Magneto. The magnet isconnected to the ignition switch in the cabin if so. a single one is usually a keyed rotary switch like this, if it's a twin it's usually a series of individual toggle switches and there are several different types of switches but the switch in the cabin that turns the chargers on and off connects to the charger through a wire called P wire and to turn off the charger the magnetic switch shorts that P wire to ground so that even when the points open the top of the primary is connected to ground through the PP wire and therefore the magnetic field never gets to collapse and it never gets to uh-uh it never gets to trip the plugs the P wire is a shielded wire with the shield grounded to the magnet case it's very, very important that The P cable is shielded and the shield is properly grounded because if it is not, then the P cable ends up becoming a big antenna that radiates all kinds of impulsive noise and wreaks havoc on your radios.
A very common problem is to start hearing static pulse noise on radios and the most common cause is that the P ground wire has broken or disconnected or the screw that your ground connection has come loose or something like that and if the wire P is not grounded, it will radiate all sorts of power-on noise on radios, it will also go off on GPS and cause an ADF to go haywire if the P wire is broken, disconnected or accidentally left disconnected. We have a condition called a hot bag where the magneto cannot be turned off from the cockpit and that can be a potentially dangerous situation because on many airplanes if there is a hot bag and you manually turn the propeller, the engine could start even though you think everything It's off and like I said if the engine cuts out you'll get a lot of ignition noise, you already know that in your rating.
Magneto timing is important, it is very, very critical. In order for the spark to occur at the correct time, there are actually two different types of Magneto timing, one called internal timing, also known as egapp, and the other called external timing, also known as magneto-to-engine timing, the egapp or Internal timing is normally adjusted when the magneto undergoes its 500 hour inspection which we will talk about and is an adjustment that is made internally to the magneto and its purpose is to ensure that the points open at the point of maximum voltage induced in the magneto. primary to generate the hottest. parts can spark over time as the points where and as the cam, particularly the kam, is in a slippery magazine or the cam follower, where it is in a Bendix magazine, the egapp or internal timing will drift and , as it drifts, the mags output voltage will gradually decrease, so if the egapp is allowed to drift from the charger, the charger will activate and the ignition performance will be less than optimal again.
This to adjust the internal timing, the charger must be opened. and we normally do this at a 500 hour inspection, the external timing is adjusted by rotating the magneto in its bracket on the engine and the external timing is adjusted exactly when the spark plug fires normally, this will be indicated by the engine specifications and nameplate. engine data. What is the right time for the charger, it is generally between 20 and 24 degrees before top dead center. There are some engines that actually time at twenty-eight degrees and it is very, very important that the chargers be adjusted so that the spark fires exactly at the right time, normally, this is adjusted, checked and adjusted at each annual engine inspection. 100 hours and as I said, this does not require disassembling the magneto or removing it from the engine.
You check it with a timing light which I'll show you in a minute and then if it needs to be adjusted you simply loosen the mounting nuts holding the charger to the engine and turn the charger slightly one way or the other to get the correct timing. This is a typical piece of equipment used to adjust the external timing of the mangrove synchronizes the charger with the engine there is a timing indicator with a degree scale and there is a charger timing light that connects to the P wires of the magneto and allows you to determine exactly when the points open and you must set it so that the points open at exactly the number of degrees before top dead center that is indicated in the engine specifications and on the Internet to play today.
This timing indicator illustrated here is somewhat dated and is usually difficult to obtain. Much closer than one degree of accuracy today we tend to use digital inclinometers that give you the levels that you can buy at Home Depot and they're accurate to a tenth of a degree and it's a better way to do it. Starting the engine with a magneto ignition system is a special challenge and the reason is that actually two things, firstly, at the typical starting speed of an engine which is about 50 rpm, in other words, how fast the starter motor runs that will turn the engine.
The magnetic rotor does not spin fast enough to generate enough power to ignite the spark plugs. What is called input speed, which is the minimum rpm required to fire a spark plug, is usually anything above 150 rpm and starter motors simply do not work. It doesn't start the engines as fast, so getting enough voltage from the magneto to start the engine is a problem. The other problem is that even if the charger could generate enough voltage at 50 rpm, the spark timing, which is normally, as I said, 20. to 24 degrees before top dead center if the spark plug were to fire 20 to 24 degrees before us before top dead center with the engine starting at 50 rpm, it would cause the engine to kick back, so to start the engine we have to timing between 25 and 35 degrees from its normal timing for the spark to actually ignite, sometimes something slightly after top dead center instead of 20 to 24 degrees before top dead center, so we need to have a scheme to achieve both first. while generating a voltage to fire the spark plug and secondly retarding the timing to cut off, allowing the engine to start without backing up and there are two schemes to do this, the most common is called boost coupling.
The impulse coupling is a mechanical device. which is attached to the Magneto rotor shaft and is located between the Magneto and the engine drive gear. I'll show you a picture of one of these on the next slide, but basically it consists of the clever arrangement of springs and flyweight operated Pauls that caused when the motor tries to turn the mag, it actually locks the mag in place and makes The engine winds a spring and then, after the spring has been wound between 25 and 35 degrees of crankshaft rotation, the pawls are released and allow the spring to break the mag much faster than the engine speed, which It allows you to generate enough voltage and also retards ignition by the amount required so that the engine can start.
Another approach is called a magneto switch or also known as a spark shower system, which was a trademark that Bendix used for this and in this schematic, instead of having the impulse coupling with the poles and the springs and all that, the magneto contains a second let's say set of breaker points that are synchronized with the cranking time, so when the engine starts, the charger runs on this second set of breaker points instead of the normal breaker points, which which causes the spark to fire after top dead center. instead of before top dead center and the system also contains something called a starter vibrator, which is like a small doorbell that provides DC pulses from the aircraft battery to provide the voltage to generate the spark from the charger turns over. slow to generate enough voltage on its own so the switch system again uses a second set of points and uses a starter vibrator and between those two components it is able to start the engine.
This is what an impulse coupling looks like. on the right you can see with the spring inside the impulse coupling and the motor winds that spring, those Paul prevent the magneto from rotating while the well spring is wound and then when the spring is wound about 35 degrees, Paul suddenly releases the spring and causes the magneto to generate a voltage high enough to fire the spark plugs and about 35 degrees once the engine starts, centrifugal force causes the fly weights to retract the pulse and the boost coupling stops working and the motor just drives the magneto directly when you turn off a motor that has impulse couplings when the motor stops in the last few rotations you will hear a clicking sound as the impulse coupling starts to do its job again so you can always tell by ear if An engine has impulse couplings or a spark shower because the impulse coupling makes a clicking sound if you turn the propeller by hand, it also makes a clicking noise when the engine is shutting down and the shower does not produce sparks. any noise, the shower spark system circuit breaker system looks vaguely like this, it has a second set of circuit breaker points at mag time to start time and when the start switch is activated it causes the mag is tripped using the breaker instead of the normal breaker, then when you grab it you release the start switch, it goes back to using the normal advance breaker and like I said there is also a vibrator that makes a pulsed DC from the Boat battery is supplied to the circuit breaker to provide voltage for Spark Start Here is a diagram of what the spark shower system or switch system looks like.
It is a simplified diagram. It's actually quite complicated, but the starter switch on a spark shower system has a bunch of different contacts that, in addition to grounding. The P wire also ends up energizing the ignition vibrator and connecting it to the circuit breaker points. I'll talk a little about baggage checks. The traditional magnetic control found on your Poh is what we call an RPM drop test. The procedure is slightly different. Depending on whether you are running a continental engine or a Lycoming engine, the Continentals usually specify doing the magg check at 1700 rpm and you switch from both to one mag and then the other mag and usually the Poh will say that the drop maximum acceptable is 150 rpm and the maximum difference between the left and right mag is 50 rpm which can vary a bit from Poh to Poh but those are generally the parameters for most continental engines or continental direct drive engines like homing is a little different and in fact, Lycoming changed their guidance a year or two ago and something called service instruction 1132 B, which is probably more current than what's in your Poh, if you have a Lycoming-powered airplane, it requires checking controllable pitch propeller motors at 50 to 65% power and check the fixed ones. pitch propeller motors at 1,800 to 2,000 rpm.
I think most Pohs, as I've seen from Lycoming, require 2,000 rpm running. The new thing that was introduced in these service instructions is that the old Lycoming guide used to be to do the mag check at full richness and the new guide is to do it lean at maximum rpm, which is basically the best combination of power and Lycoming's guide calls for a maximum decay of 175 rpm and a maximum diff of 50 rpm, now all that. The manufacturer's guide was written assuming the aircraft has jurassic instrumentation today many of us hopefully have some type of digital engine monitor with egt probes on each cylinder and if you have a digital engine monitor I recommend it . ignore the rpm drop and pay attention to, say, the T's because it's a much better indication of what the ignition system is doing than the previous rpm drop and you basically want to do the pre-flight magnetic check of the same way as at the same rpm and so on as before, but instead of looking at the tachometer, you want to look at the engine monitor.
When you turn off a charger, all the EDT bars should rise, none of them should fall. They should normally rise between 50 and 100 degrees Fahrenheit, it is quite common that they do not all rise the same amount, in fact it is very common for the odd numbered cylinders to rise more than the even ones or vice versa depending on which Maggie is running. absolutely normal but you need to make sure that all the egt bars go up and once they have gone up they stay fairly stable at the higher values ​​and that the engine runs smoothly with one Magneto and then you try the same with a second Magneto. and this is how I do my magnetic checks.
No, I don't pay attention to Technician Homer. I look at the engine monitor. Now the preflight charger checks if you are doing this using the tachometer or using an engine monitor. It is not a very demanding or demanding test of the ignition system and, in fact, will only detect the most serious problems. A much better estimate is to do some in-flight magic. To do magic in flight, you must have an engine monitor, obviously not. There will be arpm drop, especially if you have a controllable pitch propeller because the propeller will keep the RPM constant, so what we are looking for in a magic in flight is that it increases, for example, that it is stable, for example, that the engine T run smoothly with a mag.
The best in-flight magic is done at the leanest cruise setting possible, preferably Lena Peak, the leaner the mixture the harder it will be for the spark plug to ignite, so if you want, if you want to turn the ignition system to max . stress test and really check its condition, you want to perform this as efficiently as possible and I said if the engine is capable of running Lena peak, it is better to do this test Lena P, we want to shut down each charger individually. the engine running on one mag for at least 30 seconds make sure all the egt bars go up and none fall back down if the odds go up more than the evens or vice versa that is normal make sure the engine is running relatively smoothly at each mag individually now the engine will always run a little rougher with one mag than with two and that's particularly true if the mixture is very lean, but if it runs rough enough for your passenger to tell what's wrong with the engine then it's probably Too rough if you have a constant speed propeller, of course don't expect an RPM drop when you do this because the controllable pitch propeller will keep the RPM constant.
We're looking at, for example, T here, we're not looking at the quick RPM note. About high altitude operation for turbocharged aircraft flying at flight levels there is a unique problem which is called high altitude misfire as the aircraft climbs to higher and higher altitudes the more the manifold pressure increases between The outside environment, the harder it is for the magneto to fire the spark plug and if it becomes hard enough to fire the spark. Engaging the spark may cause our arc to pass through the inside of the magneto distributor block instead of arcing across the spark plug as we intended.
If that happens, the engine will become extremely harsh. It's actually a pretty terrifying experience. You will find that if this happens, reducing the manifold pressure makes the problem go away and descending to a lower altitude makes the problem go away. If this happens to you after returning to the ground, you will want to have the magazines removed and opened because arcing inside the distributor cap can cause significant internal damage to the Magneto similar to the picture we saw with a carbon brush problem, There are a lot of plastic pieces inside the Magneto and if there is significant arcing inside the charger it can start to melt those pieces as the spark plug gaps get larger.
The likelihood of this type of misfire occurring at high altitude increases, so for airplanes flying at flight levels it is very important to perform regular spark plug maintenance and keep the spark plug gaps tight. Most spark plugs are specified to have a gap between sixteen thousand and twenty. thousandths and you want to try to keep it at the narrow end of the range to provide maximum misfire protection at high altitude when you're flying flow levels. The two methods to prevent misfires at high altitude are to use a physically large Magneto where the electrodes inside the distributor are so far apart that it is almost impossible to have Ark over them all.
I'm talking specifically about the Bendix s 1200 chargers that we'll look at on the next slide or the slide after that, which are very The large Magnetos are what I use on my airplane and they are very, very capable at high altitude because the spacing between the electrodes is very big, but the math must be big enough that they don't. Fits uncertain engine installations, the other solution if you have to go high using a small charger like a slick for example, is to pressurize the magneto by pumping compressed air into the magneto. Air is a very good insulator and will minimize the chance of internal arcing even when the charger is relatively small and the various distributor contacts are fairly close together, the problem with pressurizing the charger is that it increases maintenance of the charger. charger because when you're pumping air, the compressed air from the turbocharger through the charger, you're also pumping a certain amount of moisture and contaminants through the charger, so pressurized chargers tend to have a lot more corrosion and contamination problems and They require more frequent maintenance than non-pressurized ones.
The pressurized charger installations I have seen use a single pressurization source and a single air filter to pressurize both chargers and if something goes wrong, for example if the small plastic nozzle on the pressurization filter breaks, both chargers will go. and they will pressurize simultaneously in both. The chargers can start to fail at the same time, so it's really a single point failure that can kill both chargers at once, which isn't really the best idea, but those are the two approaches I would use anyway. They are used to address high altitude misfires in aircraft. that fly high either using a large magneto like a Bendix s 1200 or pressurizing using a smaller magneto, but the pressure increases, it is very important that these Magneto come out of the engine and open for a 500 hour inspection.
Magnetos are one of these things because we have a lot of plastic parts that are very prone to failure inside, etc., and things that wear out like carbon brushes, etc., that have to be opened regularly and, although it is not required by regulation , we are very, very religious about opening the magazines every 500 hours, um, you don't need to check them every 500 hours, we normally don't ask for a check, we ask for what's called an Iran inspection, the necessary repairs, usually the The cost of doing this will be something like four to six hundred dollars for each magneto, depending on how many parts need to be replaced.
Normally, the points are always replaced, the carbon brush doors are replaced, a lot of lubrication is replaced and so on, but it is a very careful inspection and sometimes additional parts. It needs to be replaced, so doing these 500 hour Irans will cost about a dollar an hour per man, but it's really very important to do it, as a lot of shops will do it in-house, we'd rather not let them do it. We prefer to send them to a magneto specialist because most shops simply don't have the tools or knowledge to do this job right, so we usually always send them to one of the numerous Max specialists around the country who do nothing . but the work on Magneto in Iran includes a complete disassembly inspection, replacement of various points of consumables, carbon brushes etc., there is a lot of cleaning and lubrication, the gap between the egapp and the breaking point is made or adjusted, then the Magus is reassembled and, if so, so it is. made in a magneto shop, they usually have a test fixture where they can, they can run the charger on a Tex test fixture and actually do a stress test to make sure it's putting out the correct voltage, etc., if Your local mechanic does it, they usually don't have the equipment to do that, that's another reason we like to send them basically four different series of Magneto that are in common use.
The one on the top right is the Bendix s 1200, it is physically very large. mag, very robust, produces a significantly hotter spark than any of the others, is very good for high altitude work, if you have the choice between Magneto and can fit an S 1200 in your engine, it is, without a doubt, the best Magneto that can. you can buy it, it will not fit all engines because it is quite big. The smallest Bendix is ​​the s20 RS 1200, depending on whether it is a boost coupling, Nagre magnetic switch, but they are basically the same charger, it is an older design, a smaller design than the S then has 1200, it is a pretty good charger, if you use these things at altitude you have to pressurize them.
The third is the Bendix twin charger, which wasn't really a wonderful concept in the first place and now aircraft owners. Those with dual mag equipped engines are in a world of hurt because Continental stopped supporting them and stopped making parts for them. The number of spare parts is still available from third party suppliers, but there are some spare parts that are simply not available. The dual charger is manufactured by Bendix, which is owned by Continental and is used only in Lycoming engines. What's wrong with this image? This is probably a big reason why Continental made the decision to stop supporting that charger because it is not used. on any continental engine it is only used by the competition anyway if you have a lycoming engine whose model number ends with a D that means you have a dual charger and these chargers will become more and more problematic because many of the parts simply no longer work you can get the fourth mag it's the slick mag a slick used to be owned by unison it's now owned by champion the slick is a small mag it's generally less robust less durable putting the saddle on it's not as hot as a spark like the Bendix mags but They are used a lot because they are very cheap and you can exchange them for about eight hundred dollars, so often people don't even bother making Iranian magazines, they just throw them in the trash. that are not thrown away, but are changed for a minute that every 500 hours for an overhaul and a factory exchange magazine are not my favorite magazines, but they are used very frequently, they are light, inexpensive and particularly slippery more than any other simply because they are less robust really really really really have to be replaced or disassembled every 500 hours you don't want you don't want to push your luck it's like mag finally just a couple of quick points on troubleshooting, there's a lot more about this in my webinar on the engine monitor, but very quickly, if you are flying and you see an egt on the engine monitor rise well above the others, that usually indicates that a plug in that cylinder is not firing, it could possibly indicate that the ignition wire is faulty but it is most likely a faulty spark plug, on the other hand if you see the raised GTS oli that normally means the entire magneto when the magneto is not firing so the difference between a bad mag and a bad plug is a tail plug that causes them to rise 180 T, but a bad mag causes all GTS to rise too if you take your plane out of maintenance, have an annual inspection or something and you notice that the CH TS are taller than you.
You are used to seeing and for example the T's are lower than what you used to see, it means that the magneto that the mechanic screwed up the ignition timing and advanced the timing is a very dangerous situation because it reduces the detonation margin in the engine , so if you see If you take the plane out of maintenance and see elevated CH TS and press the TG Ts, put it back in the shop, tell them to change, check the ignition timing because they probably screwed it up, the opposite is if, for example, the T's are all high. and the CH keys are down, the ignition timing is a much less dangerous situation, all it does is cause the engine to put out a little less power, but it won't cause anything to explode, but in any case, the first time you pull the plane. from the shop after a year or any other time the mechanic has touched the Magnetos you want on their first flight check the CH TS Andy GTS and make sure they are all where you expect them to be and if CH e sr high on e GT s are low or vice versa, you have a problem with the ignition timing, you want to put the plane back in the shop and ask them to correct the timing, hey Mike, yes sir, we have had several questions.
Oh or in questions oh yes, we are, we are, it's not that, it's not that amazing, how amazing, let me make just one comment before we get into the questions, and that is that Charlie probably won't answer all the questions that have been asked. been answered. I have my email address up here and if he has asked a question and you don't get a response, go ahead and email me your question and I will try to respond to each one to give each of you a personalized answer. Go ahead, Mike, you must be clairvoyant too because there is absolutely no way we can get through, but I think there's one who's probably been asked at least six or seven times and that's OMG, he's got over 600 people in the room. .
Wow, yeah, we had a great turnout tonight. Clum and I think Shawn probably sums it up as well as any of the other questions. When I do a charger check with an engine monitor, why does the e GT crank up when I turn off one of the chargers? I wish I had thought about the mix. it wouldn't burn as well causing a crash on the GT, that's a very good question and I'm happy to answer it. This is how it works when switching from two mag operation to one mag operation, the combustion event in the cylinder. has a single ignition point instead of two ignition pointsignition, so instead of the air-fuel mixture igniting from two different places and burning toward the center of the combustion chamber, which is what normally happens, it ignites from a single spark plug and has to burn the entire the combustion chamber from that single ignition point, as a result, the combustion event takes longer to complete simply because it is a single flame front instead of two flame fronts approaching each other and because ignition due to the event The combustion chamber intake has no longer had time to cool down as much by the time the exhaust valve opens and when you think about it, the EGT probe doesn't see anything that's going on on the combustion chamber side, it just starts to see. something when the exhaust valve opens, although it is true that igniting the mixture with a single spark plug produces less energy and causes a slight loss of power, which is why we actually have a drop in RPM, the combustion gas is hotter at that moment. the exhaust valve opens because the combustion event is progressing more slowly, but the exhaust valve opens at the normal time, it does not know that we are operating on May 1st and therefore the gas coming out of the exhaust valve exhaust and passes through the EGT probe is hotter.
I hope that's an explanation everyone can understand. I think that covers it all. Here is another cable charger still used in general aviation engines. Three words. F a a. Basically the reason chargers are still used in general aviation engines is because to certify an electronic system. ignition system FAA certification hurdles are extremely high. Non-magnet ignition systems typically rely on having an external power source and for the FAA to accept an electronic ignition system requires an electronic or I mean electrical power source that is essentially totally bulletproof. In fact, there are requirements for it to resist the electromagnetic pulse, in other words, what would happen if an atomic bomb exploded?
It's always seemed to me that if that, that, that, if a nuclear warhead exploded, you know, on the tip of my right wing, the loss of ignition would be my least concern, but the FAA doesn't seem to see it that way at all. case, the reason is that the FAA in its certification requirements has created certification hurdles that make it extremely difficult to use an electronic ignition in a certified engine. There are a couple of systems that are approved, they are gradually beginning to enter the mainstream of Commerce. , but the FAA has made it very, very difficult and most electronic ignition systems used in experimental aircraft simply do not meet FAA certification requirements, which you know. most people think they are excessive, but you know the FAA is the FAA.
Randy would like to know if it is still possible to make an in-flight charger with a single EGT meter that has been properly tilted. Well, you can do it, but no. I get a lot of information and I wouldn't hesitate to do it on an engine that only has an EGT gauge or even no EGT gauge at all, I just look to see if the engine runs smoothly with a charger but if there is a problem you know without an engine monitor . You can't really see where the problem is with an engine monitor. You can say, oh yeah, the bottom spark plug on cylinder number three has given me a problem here without an engine monitor.
You can't get that information. I won't do it. Go into my long rant about why all airplanes need to have a diesel engine monitor, but I think I can sum it up to the fact that I think Mike Bush would say it's the best money spent on an airplane, sure that's pretty good. Lawrence would like to know if having two chargers with boost coupling helps with starting in cold weather compared to a single boost, probably, which is why the shower spark system is actually the best. The shower spark system, due to its nature, actually fires a series of sparks rather than just a single one and is exceptionally good for cold starting, but yes, having impulse couplings on both chargers will give you double the chances of achieving this: making it fire, so it would be an advantage if some pulse coupled motors have impulse.
The couplings on both magazines and others only have it on the left magazine. Well, John would like to know what he says. I've heard that turning the propeller backwards is bad for thrust coupling. Others say it is safer because the impulse coupling will not work. It is best to turn the motor backwards as it does not damage the impulse coupling at all. Whoever told you was probably confused. The only thing people warn about turning the prop backwards is with carbon vane vacuum pumps and even that I think is a bit much, but no, turning the prop backwards won't damage the drive coupling one bit, it's okay, and Mike would like to know what the difference is between a hardware repair and an overhaul, basically the difference is that when you do an Iran, you give the magneto technician discretion to replace it. only the parts that he thinks need replacing.
When you specify a service, you take all the discretion along the way and the technician has to replace every single part that the service manual requires, which is essentially everything that could wear out. So for example in an overhaul you have to replace the bearings in Iran, you look at them, if they look good, you keep it if not, you replace them and so on for many other parts, furthermore the overhaul requires that the rotor magnetic se remag doesn't have links and Iran usually doesn't, so there are a lot of things like that, but we prefer to send the magazines to two mag experts and then give them the discretion to decide what needs to be replaced and what doesn't.
Well, and if you need to find a magazine expert, how do you find that person? I'll tell you what anyone who wants a list of our favorite magnet stores send me an email and I'll send you back. God, how many emails I get. 600 people in the room, that's a little scary, but I'll be happy to email you anyway. I'd be happy to send you a list of magneto shops that we like to use okay and then David would like to I know there is a maximum number of hours on a charger before they need to be rebuilt or completely replaced and is there a difference according to the brand of the charger?
The answer is no, if you do an IRA every 500 hours for parts that are worn out. or getting too old, for example, capacitors tend to get replaced over time, they all have a date code on them, we will end up getting replaced and some top ends will be a little more expensive than others because magnetic technology decides to replace more parts, but no, you can, you can run mags indefinitely, as long as you have an Iran done every 500 hours by a guy who knows what he's doing right and you don't have a dual mag, in which case it may eventually be fine, Jose would like that. so you know when checking, uh, when checking external magazine timing, is it absolutely necessary or is it absolutely necessary to use a propeller hub grade indicator?
Can the Marge steering wheel be trusted regarding the engine split line? My homing has a steering wheel and has the FlyLo timing marks, does he know? I don't know the answer to that, because a lycoming I know on Continentals Canal came out with a service bullet and said, don't use, don't use the timing marks because they're not accurate. I honestly don't know the Answer about the similar weather, whether you like calm allows you to use them or not, sorry, okay and Nick Nick says you've described the Magdalen in flight. I tried it on my Cessna twin a couple of weeks ago and both engines worked too.
It was hard on a charger to leave it running like that for 30 seconds. I was on the Lena Peak Cruise. Does that mean I should have tried the richer test or does that mean I saw a problem with both engines starting? Oh, it probably means both. but if you say it ran uncomfortably rough on one charger but not the other, then you surely have an ignition problem that needs to be checked if you were running uncomfortably rough on both chargers and possibly just running a little bit in two lanes, but from the description it sounds like the charger test did exactly what it was supposed to do, which is tell you that you have a problem, okay? and Laurence feels that the Matt in-flight checks are not a good procedure if a charger is not working properly and the engine is running at full power then a counterproductive effect occurs when the charger is turned back on, there is a bad idea In the hands of most pilots, goodbye to exhaust. baffles if it's equipped thoughts yes, both thoughts which one is I would admit that it's probably not a good idea to do this with your wife on the plane and the other thing is that if there is the very strange possibility that you have a completely dead mag, it would which is an infinitesimal possibility because you did a mag check before the flight and got a dead Maggie.
You know it before you take off, but in the infinitesimal case that you actually have bad mag that developed in the air and the engine dies, you do it. you don't turn the key back, you pull a mixture control, you turn the key on and then very slowly advance the mixture, check to see if the engine shuts down because the ignition is gone and the propeller is towards the wind, fuel and air are pumping . through the engine they just don't turn on and the exhaust system fills with unburned fuel air and then when you turn the key back on, of course, it turns all that stuff on and creates it, which is not a counterproductive effect, in It's actually called after a fire, but it's very, very rare that it damages the exhaust components, but it will usually scare the living daylights out of you, so if the engine goes out and this doesn't, it's not just a matter of a magnetic check, but whether the engine turns off. you don't want to turn it back on with a wrench you want to pull a mixture that is now flowing air without fuel and clean it all out then turn the ignition on and gradually turn the mixture back up and that will eliminate the problem and I wouldn't like to know how long it takes do your preflight check the way you described major preflight, yes when using the II GTS compared to the 30 seconds maybe. okay I don't know 30 seconds 45 seconds it doesn't take a different amount of time than it would take to look for RPM drop you're just looking at a different instrument okay and Jim would like to know if you have any hot start tips for hot starts, well I probably shouldn't go into that here because it's a very long discussion and it's different for four different engines, it's different for carbureted engines, it's different for injected engines like cummings in this friend and continental, so probably not a question we should try to ask here, okay, Paul would like to know what should appear in a logbook entry regarding annuals, what could appear in many, but the country depends on what was done , if nothing was done, nothing would appear. in the logbook entry, I'm not sure I understood the question correctly, your appendix D says enough, so I guess so, appendix D always infers the scope and I'm probably an amateur builder and it's probably the scope and the detail in appendix D, my guess Yes, again and again, normally you wouldn't write anything.
If you did an annual inspection, you would say that I have certified that this aircraft has been inspected in accordance with an annual inspection in accordance with part 43, appendix D. Don't say more, don't say I did anything with the magazines unless you actually did maintenance of magazines. Well, here's a question. Mike, is there a chat room associated with this webinar? If so, what is the link? We do not have a chat room. however, Mike, I think you started on the EA forums in a correct maintenance section, yes we have a maintenance workshop forum on the new EAA forums points board, yes, F once, so the Ron's organization, yes, and it has become very a very active and vigorous forum and it is a very good place to ask questions related to maintenance and you are practically monitoring that one is correct.
Yes I am. I am officially the moderator of anything I do. Sometimes I have answers. Sometimes there are people there who are much smarter than me and they responded because they didn't have enough to do. I had all the questions tonight and really that one and that was all my fault because I was like how come you guys don't have a maintenance forum? on these EAA forums and lo and behold three days later we had one that was fine David I would like to know if there is a replacement for the dual charger on a Lycoming TI or 540 s1 ad well there is but the problem is that You can really only change the chargers during the engine overhaul, all Lycoming engines.
I believe they have nandi versions, but they require a different accessory box, an accessory box that is configured to mount to individual chargers ininstead of a twin, so it's not something you can change except when you overhaul the engine and when you overhaul the engine you can install a different accessory box and the engine becomes a non-D engine, unfortunately no one makes a small and handy fancy adapter or anything like that that can allow you to mount conventional chargers on a lycoming D suffix engine that is configured for dual charger. It's a bad business. I feel sorry for the people with the engines because Canal just made the decision to run mine dry, okay, Gerard.
The axe is whether you would switch from an engine without a boost charger to a boost charger when the engine does not have a starting system and manual propping is mandatory. Well if manual propping is the way to start the engine then you have no choice but to use shower spark impulse couplings it won't work so yes it is necessary it is necessary to have impulse couplings we can prop the engine manually . Mike just to clarify. I don't think I had impulse couplings on my champion, a 65 horse, when it was supporting him with your hand if you had started him, you just had to turn him quickly no, no, but well, I honestly doubt it, okay, because I can guarantee that You didn't, you never could, there's no audible click, so I think that's what this guy has.
What the hell do you have a six 65? A 65 is not good. I have to admit, I've never worked on a 65, so I guess I need to do a little homework, but I know it's a little low. on your horse, far right, well, it's hard to imagine that a pulse coupling charger couldn't generate voltage to start the engine at manual boost speeds, but I could be wrong. I'll check. I'll check it out for you, well John chimed in and said Charlie is right about there being no mag in a 65. I know a magnet or nothing doesn't give me any boost, but I'm sure someone else will chime in too.
I may have missed this. part, but Gary would like you to explain more about the Home Depot tool oh no, I was just talking about digital level digital inclinometers to use instead of the donkey cap arrangement with a small swinging pointer, you can buy a digital levels or digital inclinometers that have a little digital readout and a little button that you press to zero it and you attach it with a rubber band to the propeller instead of wearing a donkey cap and it's much more accurate, okay, and Thomas just stepped in with a lot of a 65 they don't have boost couplings they backfire more often than not well then correct me because that's a place I've never been and Doug just chimed in saying there's a free iPhone app that has a hint of honor Oh, how cool is that.
I'll have to get that out, well, they think of the next thing, absolutely fine. Ralph says I just hit 500 hours on my chargers. My mechanic said he will inspect the chargers for wear. How does it work? How to make chargers for a long time? He usually laughs. My plate is a 1981 Piper Dakota magazines usually last forever if you take them apart every 500 hours and replace anything that's wearing out. I mean, the only thing that would prevent a magazine from being reused is, if the box cracks, then it has to. It can be rejected that there have been cases where something was damaged inside a charger and the pulp started rubbing the rotating assembly and therefore the rotating magnet assembly was not reusable and at that point it is no longer really economical to repair it, you have to replace it, but generally speaking, unless something really bad happens, you can keep a magazine in service basically forever, as long as you make a five hundred dollar Iran, that's fine and Brian has to use magazines he doesn't have.
The carbon brushes have not been used yet, something you should consider replacing with new ones. How can I know if the brushes are like the ones you mention in the presentation? There is an advertisement and the advertisement has a specific applicability section that provides dates during which, if the magazine was manufactured or rebuilt during a particular date range, then it is one that could have defective brushes and provides inspection procedures for opening the Mac, look at the brushes and see if I have a bad one, so just pull the "I do." I don't have the number at my fingertips, but it's easy enough to go to Google, take a look at the ad, and follow it.
Well, Ronald would like that. I know you showed that picture where the gear teeth had broken, would it be from wear or what would be the point of failure in that well, there are several ways those teeth can fail and unfortunately one of the most common. In this mechanical error, there is a tool that mechanics frequently use to hold the gear stationary when adjusting the egapp and if they do not remove that tool before attempting to install a charger on the engine, the gear teeth can become overloaded and break. that there are also other reasons why this can happen and also if the gears get too old and the plastic starts to get too brittle it can start to come off the teeth so there are several reasons why that can happen there is okay and just Joseph's butt yes Not yet, can you explain about the egapp in some detail?
Let's say you are collecting information in an experimental setting. Yeah, you probably don't want me to do it in any detail because we probably don't have enough time, but basically. The egapp adjustment on any of these chargers consists of first rotating the rotor until you reach what is called magnetic neutral and while you turn the rotor inside a charger by hand with the magneto off of the engine, of course, there is almost a magnetic detent, you can feel where the pulse of the magnet is rotating or aligned with the pole pieces of the coil and then you measure the number of degrees you have to turn the rotor from that magnetic neutral to the point where where the points open and there are a specific number of degrees that it's supposed to be and if it's not correct, it's adjusted in two different ways depending on whether it's a Bendix magazine or an SLIC magazine, if it's a Bendix magazine that has true honesty. -Gosh, metal cam, the cam has a screw on it that you can loosen and actually turn the cam slightly relative to the rotor and get the exactly right egapp.
The slick mags don't have a real cam, they have that little piece of plastic. that installs in that slot on the rotor shaft so the only way to adjust the gap on a polished charger is to adjust the points and the polisher gives you a very wide range of acceptable point gaps so you can adjust the gap of points to be larger or smaller so that the egapp or this number of degrees between the magnetic neutral and the opening time of the points is correct, that is probably all I should say on the subject. If you want to know more, both manufacturers have magneto. maintenance manuals detailing all that, okay and Chris chimes in, according to Paul Milner at CFO quote, there are only three non-aftermarket parts for the D magazines according to Kelly aerospace and those approvals were in the works so maybe Maybe there is some hope on the horizon for the D mag people, that's good.
I know we recently had a customer that needed a replacement impulse coupling spring and they just work, we can't get them but I guess that's good news. that Kelly is going to get approval for those parts, it's bad news coming from Kelly, in fact it's probably not Kelly anymore, it's probably Hartzell and engine technologies because they bought Kelly or most of Kelly's stuff, but Its quality guarantee has not been the best. but anyway, it's certainly good news if those parts are going to be available. Well, Mike, great webinar. We've spent a lot of time just reminding everyone.
Mike hosts a webinar on the first Wednesday of every month. The only exceptions are. maybe if there's a holiday or AirVenture right there, then we could push it back a week, but the next one you'd like to mark on your calendar is deciding when to do the review and that's February 1st, am I right? that Mike is right and this is a brand new webinar and it's going to be really interesting on the topic is when to review and the answer is not in tbo oh let's leave it at that you're tipping your hand any final thoughts tonight Mike no I'm a unimpressed by the turnout.
I hope the trend continues and if the trend continues, you're going to have to figure out what we're going to do when we get to a thousand, well, someone said. I have to buy the beer if we get to a thousand and one, okay, I said, I hope I have that problem, one left this time of year, it will probably be hot chocolate, right, yeah, a reminder is that if you want to watch the recording. of tonight's webinar or any of Mike's previous webinars just go to EAA dot o-r-g slash webinars and we have a red button that you can't miss, it says webinar archives and you can go back and review any of the previous ones that Mike has done so if you want to go back and see his engine monitoring one or any of the others he's done go check them out thanks everyone for tuning in and thanks for being a nema be a member and stay warm tonight everyone thanks to all.

If you have any copyright issue, please Contact