As a Certified Mechanic I rebuild and service a lot of magnetos. Many times I have had to replace the entire rotor due to corrosion on the magnet & shaft so severe that the shaft broke in two pieces after pulling the bearings off. Worse is neglecting the magnetos by not flying the aircraft due to neglect of routine maintenance & annual inspections regardless of time on the engines. Such neglect will have you paying more in the long run and your aircraft's value decreases substantially.
I disagree with 500 hour IRANs, every magneto I've opened has moderate to severe burning on the electrode fingers, and the assembly alone is like 500 dollars for this, the carbon brushes I see are always way within limits. Add in a contact point kit which is like 200-300 dollars and you already meet the cost of receiving an overhauled magneto often times. You also have to take into account the time it takes to perform a 500 hour magneto inspection as opposed to just changing out gears if necessary and installing overhauled magnetos. If you go off of the overhaul manuals, you will often find enough stuff in a 500 hour magneto that exceeds the cost/time of changing out internal components as opposed to getting an overhauled one.
It's interesting how the design of aircraft engines has lagged behind current engine technology. Cars have electronic ignition, some don't even have distributors or a single ignition coil. Now I realize that a computer needs a separate power supply incase of an alternator or battery failure. Electronic ignition does exist in aviation but it's experimental and is usually pared with a mechanical ignition system for redundancy.
25+ years ago, electronics were not entirely reliable. Today; ecu's, batteries, ignition coils, sensors are far superior and surpass these old pushrod engines. Pretty much all electronics are now solid state.
I’ve had a very unusual snag on my Franklin 150 engine equipped with Bendix S6RN-21 mags. The engine runs smoothly at idle up to about 1700 rpm where it starts running very rough to the point where I have to pull the throttle. I’ve changed the plugs, the carburetor and both magnetos. Fuel flow is 35 g/hr ( recent fuel) and compression is over 76/80 on all cylinders. Could components like capacitor or coil create erratic ignition at high rpm?
It does not matter, either a battery & coil ignition set-up or a magneto, even the model; T coils in the wooden boxes had a condenser in them, the condenser being wired across the points of coil's vibrator. juice came from the "MAG' which was a low voltage magneto, V magnets spun past a series of coils in the bellhousing or shroud or from a battery of either a number of #6 dry cells or a wet lead acid type battery. a switch was for MAG or BAT/OFF and a commutator type switch worked each coil.
Mike, I've been searching for an expert in this field and so i found you. I fix small engines both 2 & 4 cycle in the lawn care industry. I heard of a problem, have not seen it for my self, but am very very curious what could be the cause. So here it goes. My friend got a Stihl chainsaw that would bogg down.He saw the culprit to the problem as there was a spark between the magneto/coil and the magnets on the flywheel which was in direct correlation with the bogging down-the spark got stronger as he tried to rev it up then the engine boggs down. He then purchased both a new flywheel and coil from Stihl and still has the same problem. How is this spark, in that location, possible and what can be done to diagnose and/or fix it? I have never seen or heard of such I thing as I have repaired small engines for a long time. It would seem to mean there is a leak or bad ground possibly? What are your thoughts?
if the ground wire somehow gets any voltage on it it can do a similar symptom. Also i would check to see if anything is connected in reverse, if there was anything else replaced recently??
Mike we must place ,new knowledge to get rib off the magneto point and Condenser, and use the impulse , system used on high performance Automobile engine ,is much much better than the point condenser set up
At about 33:04 you mention Lycoming's Service Instruction 1132B and state the instruction now requires lean to peak while performing the mag check. But that's not exactly what it says. You're to start with full rich but if you have a drop of more than 175, then you are to go lean and repeat (am I reading the SI correctly?) www.lycoming.com/sites/default/files/Magneto%20Drop-Off.pdf
Christopher, you are reading the SI correctly. One must only lean for the test if there was a drop of more than 175 rpm. The SI states to leave the mixture full rich for the mag check UNLESS you get an excessive drop. Thank you for the clarification.
Got it. Thanks! Love these presentations by the way. They're part of what has inspired me to get an A&P cert. I have no intention of working as one; just want to work on the plane I buy and have a better understanding of the plane's health.
YUP. the condenser absorbs the inductive kickback of the primary circuit being open. This condenser will always bee seen in any ignition circuit using 'points' like in an auto ignition coil using 12 volts or an H4 magneto on a farmall tractor.
All ignition need the so call condenser/ capacitor to fire the engine , engine run on the DC corrent that it's stored in the capacitor, if remove that device of system engine don't fire a u don't know try to take off that and your engine not going to work
Started as very informative but the credibility was lost on real practical questions. I have a Continental A-75 with no impulse on either magnetos and it starts with no extra effort than the ones with impulse at our field. Also, Slick Mags are popular for a reason and I don't agree that aviation community (by majority) will switch over to the 'less robust' product just because its cheap.
1:35 Components and Operation
14:15 Common Failure Modes
20:59 Magneto Timing (Internal and External)
25:14 Starting (Impulse/Snapper Coupling, SOS)
32:43 Mag Checks
38:52 High Altitude Operation
43:44 500 Hour Inspection IRAN
46:11 Mags Makes and Models
49:48 Trouble Shooting
52:07 Questions
Khotso thank you sir
Thanks for the time you spent making this video
I am working on getting my A&P and this video has been great. Thank you!!!
lizperr my O&P for G&P is in a couple weeks. Mags are definitely something I need to work on some more. Best of luck to you
As a Certified Mechanic I rebuild and service a lot of magnetos. Many times I have had to replace the entire rotor due to corrosion on the magnet & shaft so severe that the shaft broke in two pieces after pulling the bearings off. Worse is neglecting the magnetos by not flying the aircraft due to neglect of routine maintenance & annual inspections regardless of time on the engines. Such neglect will have you paying more in the long run and your aircraft's value decreases substantially.
Excellent film footage and sound. Great tutorial for refresher.
Great seminar!
Excelente explicación gracias hermano
I disagree with 500 hour IRANs, every magneto I've opened has moderate to severe burning on the electrode fingers, and the assembly alone is like 500 dollars for this, the carbon brushes I see are always way within limits. Add in a contact point kit which is like 200-300 dollars and you already meet the cost of receiving an overhauled magneto often times. You also have to take into account the time it takes to perform a 500 hour magneto inspection as opposed to just changing out gears if necessary and installing overhauled magnetos. If you go off of the overhaul manuals, you will often find enough stuff in a 500 hour magneto that exceeds the cost/time of changing out internal components as opposed to getting an overhauled one.
Mike ROCKS!!
Much obliged!
It's interesting how the design of aircraft engines has lagged behind current engine technology. Cars have electronic ignition, some don't even have distributors or a single ignition coil.
Now I realize that a computer needs a separate power supply incase of an alternator or battery failure. Electronic ignition does exist in aviation but it's experimental and is usually pared with a mechanical ignition system for redundancy.
25+ years ago, electronics were not entirely reliable. Today; ecu's, batteries, ignition coils, sensors are far superior and surpass these old pushrod engines. Pretty much all electronics are now solid state.
This can be watched at 1.5x speed very comfortably
Thanks again
Can a bad tuning Magnetos cause engine vibration? Thank you
Hi mike, my name is mike busch are you my evil twin? Like your video!
I’ve had a very unusual snag on my Franklin 150 engine equipped with Bendix S6RN-21 mags.
The engine runs smoothly at idle up to about 1700 rpm where it starts running very rough to the point where I have to pull the throttle. I’ve changed the plugs, the carburetor and both magnetos. Fuel flow is 35 g/hr ( recent fuel) and compression is over 76/80 on all cylinders.
Could components like capacitor or coil create erratic ignition at high rpm?
It does not matter, either a battery & coil ignition set-up or a magneto, even the model; T coils
in the wooden boxes had a condenser in them, the condenser being wired across the points of
coil's vibrator. juice came from the "MAG' which was a low voltage magneto, V magnets spun
past a series of coils in the bellhousing or shroud or from a battery of either a number of #6 dry
cells or a wet lead acid type battery. a switch was for MAG or BAT/OFF and a commutator type
switch worked each coil.
Would it not be a reasonable thing to verify the timing of point break on both lobes of the cam during the 500hr inspection?
Por favor alguien que me dé información para partes de Magneto Bush para motor de 2 cilindros
Mike, I've been searching for an expert in this field and so i found you. I fix small engines both 2 & 4 cycle in the lawn care industry. I heard of a problem, have not seen it for my self, but am very very curious what could be the cause. So here it goes. My friend got a Stihl chainsaw that would bogg down.He saw the culprit to the problem as there was a spark between the magneto/coil and the magnets on the flywheel which was in direct correlation with the bogging down-the spark got stronger as he tried to rev it up then the engine boggs down. He then purchased both a new flywheel and coil from Stihl and still has the same problem. How is this spark, in that location, possible and what can be done to diagnose and/or fix it? I have never seen or heard of such I thing as I have repaired small engines for a long time. It would seem to mean there is a leak or bad ground possibly? What are your thoughts?
if the ground wire somehow gets any voltage on it it can do a similar symptom. Also i would check to see if anything is connected in reverse, if there was anything else replaced recently??
thank you sir
Mike we must place ,new knowledge to get rib off the magneto point and Condenser, and use the impulse , system used on high performance Automobile engine ,is much much better than the point condenser set up
I was wondering too, these are like my 1972 cars with ignition points.
Busco Magneto para motor de dos cilindros
At about 33:04 you mention Lycoming's Service Instruction 1132B and state the instruction now requires lean to peak while performing the mag check. But that's not exactly what it says. You're to start with full rich but if you have a drop of more than 175, then you are to go lean and repeat (am I reading the SI correctly?) www.lycoming.com/sites/default/files/Magneto%20Drop-Off.pdf
Christopher, you are reading the SI correctly. One must only lean for the test if there was a drop of more than 175 rpm. The SI states to leave the mixture full rich for the mag check UNLESS you get an excessive drop. Thank you for the clarification.
Got it. Thanks! Love these presentations by the way. They're part of what has inspired me to get an A&P cert. I have no intention of working as one; just want to work on the plane I buy and have a better understanding of the plane's health.
How about always leaning to peak RPM for every runup? I recall the Embry Riddle story from Mike's leaning video.
Assuming your engine is modern enough to have the capability to lean it.
Mike are u there?
YUP. the condenser absorbs the inductive kickback of the primary circuit being open. This
condenser will always bee seen in any ignition circuit using 'points' like in an auto ignition
coil using 12 volts or an H4 magneto on a farmall tractor.
All ignition need the so call condenser/ capacitor to fire the engine , engine run on the DC corrent that it's stored in the capacitor, if remove that device of system engine don't fire a u don't know try to take off that and your engine not going to work
Started as very informative but the credibility was lost on real practical questions. I have a Continental A-75 with no impulse on either magnetos and it starts with no extra effort than the ones with impulse at our field. Also, Slick Mags are popular for a reason and I don't agree that aviation community (by majority) will switch over to the 'less robust' product just because its cheap.