The following is good information about magneto problems from Jim Montague...

Well, We made the deal & Mark went down to Houston & looked it over for the ferry permit. It ran up fine, but 20 miles out a mag quit, so he returned to the airpark. Inspection revealed a melted coil. AD 94-01-02 R2 had not been done. Mark called me and asked if I had another S6LN-21 mag. (I do) He was going to check the other mag too.. The ex-owner claims he licensed the airplane a couple years ago, and paid for a new mag coil. By the way, all coils for those mags have to be RED now.

Steve Wilson also added this...
Do not accept mag coils with printing stamped into the red covering. They are developing cracks around the impression. Accept only those with rubber stamp printing on the exterior.

Then, a couple of days later, Steve Wilson also added this...
OK...I got to work this morning and called Bob Bejna. He refreshed my memory and I was right and wrong on what I said before about mag coils.  The cracked coils were manufactured by Electro-Systems, NOT Bendix. There apparently is no problem with the red Bendix coils.  Electro-Systems coils come in two colors; blue for 1200 series and red for 20 series. Both had "some" manufactured with the part numbers stamped INTO the covering and both developed cracks which in turn leaked and shorted out. Bob says when he brought it to their attention they willingly excahnged the coils and replaced them with Bendix coils. Now that should tell you something!  Anyway, if you have Bendix coils, forget my past communications. Sorry about that!!! If however, you happen to have Electro-System coils beware!!! There are no AD notes or SB's on this issue and aparently the offending new coils have been removed from the system, but no one knows how many bad ones may be in service.

Bob Runge (, Swift N80528 s/n31, writes:
What is a good runnup procedure for a C125 to check mag drop and carb heat.I have no written procedures for preflight, pretakeoff checks and want to construct them.”

Bob: When running up a C-125, note the ammeter at about 900 rpm, it should move slightly over to “charge”, at some speed over this, the flaps should be cycled, during the time the pump motor is running the needle should be almost to “full charge”. This is only true if someone over the years has not rewired the system - but as originally wired by the factory thats the way it works. At 1700 rpm switch from both to left magneto, max permissible drop is 75 rpm. Then switch from both to right magneto, max drop is again 75 rpm. The service bulletin for this is M68-4. When checking carb heat, a drop of 100 rpm or so is typical, just make sure you have some drop. A 200 rpm magneto drop indicates a bad plug, or bad spark plug lead. Misfiring usually indicates fouled spark plugs.

Subject: Spark Plugs
To: Bud England <>
Where in the world can I buy a C-26 plug? My Champion distributor didn't know what I was talking about. Do I really need to use the C-26 (with the right angle housing) on left front (#6) cylinder?

The later term is M41E. That's an unshielded plug, looks like a car plug, but its 18MM and has 2 electrodes like the EM41E. I have never seen it necessary to use the shorter unshielded plug, I use 6 regular EM41E plugs on top with the regular ignition harness. If you want to be strictly original, use a M41E with the Breeze shielded can. -- Jim

Subject: Re: Mags
From: Bud England <>
Here's one more for you: I have 2ea SF6 mags, plus 2ea S6 mags. Anything to choose? S6 looks easier to replace harness, SF6 looks easier to replace individual leads. SF6's have dark red coils. Haven't opened the S6's yet.

The old SF6 mags are OLD, but they have no AD notes. The S6's are a better mag, but have a bunch of AD notes. You need red coils, round rotors and the impulse couplings inspected every 500 hrs. The SF6 mags are original, but can be troublesome. If it were my project, I would call Mattituck (they have an ad near the back of Sport Aviation) and buy new Slick 6364 mags and harness and trade in your Bendix mags. I think they have a deal for about $750.00 ex. -- Jim

SLICK MAG AD... (090300)
Subj: Swift questions
From: Scott Bixler <>
Jim- Could you tell me which Slick magnetos have the AD note on them-serial numbers? Also do you have any idea where I could pick up an engine driven and an electric fuel pump for an O-300? One more question please-where can I find a diagram for the shoulder harness installation? Thanks - Scott Bixler

I presume you mean the recent AD on the current 6364 mags. It is AD 00-11-51 and the s/n's affected are 99110001 thru 99129999. If the mag was made before 10-1-99 it is probably OK. For the affected s/n's the mag must be removed and the stop pins inspected. The mags must be replaced. If the stop pins are missing, the engine must be inspected and repaired. The older 664 mags have 2 AD notes. AD 74-18-05 applies to s/n's 3080608 and below. The impulse couplings must be replaced. AD 80-06-05 applies to s/n's 9040001 thru 9040086 and this also requires new impulse couplings. The Swift Association and numerous suppliers can furnish fuel pumps. Due to liability concerns, the Facet fuel pumps now have a placard "for Automotive use only". Brand new airplanes right from the factory have this placard! The engine pump is p/n 9051 and is available from Swift Parts and many aircraft suppliers. For the shoulder harness I would call Swift Parts. There is an STC listed. See the STC listing on the Swift Page. I don't know if the holder is making it available now or not. If Swift Parts or Monte Zema can't help, perhaps Sara at Swiftworks can. <> They are not really in the business of selling parts, but they do install a shoulder harness in every Swift they rebuild. -- Jim

Subj: Slick Mags
From: Steve Whittenberger <>
Jim, I am coming up on a rebuild of my very old Bendix Mags in a few months. I would like to put Slick Mags on my Lycoming O-320. I noticed in the last Swift letter that there are STCs for all the Continental engines. I believe an investment in Slicks is appropriate now and am wondering about STCs for Lycomings. Any thoughts on this? Many thanks, Steve Whittenberger

I can do better than that! The Lycoming 0-320 A1A engines are approved for both the Bendix S4LN-21 and -20 mags and the Slick 4251 and 4250 mags. These don't require anything other than a logbook entry to install. Slick has recently come out with a newer type mag for the 0-320, the 4371 and 4370. The kit number for two mags and the harness is K4325. Do you belong to the EAA? Near the back of each months "Sport Aviation" is an ad from Mattituck. They offer the best price on a set of Slick mags and a harness, if you have a set of Bendix mags to trade in. You probably can get the K4825 kit for about $600.00 (cheap!) -- Jim

(Editor says... We recently switched from Bendix to Slick mags on Erin's O-320 and we're very happy with the results.)

SLICK MAGS ON C125...(110500)
Subj: slick 337
From: Michelle Dolin <>
Hi Jim, I recently read in the regular newsletter, that you had an approval for the slick mags for the C125. I would like to get a copy for reference, if possible. Everything is working well right now, but you never know when you might need it as a reference. We keep a file with "reference" paperwork for the Swift. Thanks, Michelle

Michelle, I had gotten a field approval to use the Slick 6364 mags on a C-125. I had my copy out of it's folder and faxed Charlie a copy. I must not have put it back! I can't find it right at the minute. For a couple of bucks I'm sure the Swift Association can provide a copy. I'm sure I didn't throw my copy away and I will find it sooner or later. If you don't manage to get one from Swift, write back and maybe I'll have mine by then. The Slick factory guy wanted a copy and I suppose I left my 337 out to send it to him. He never did get back to me. -- Jim

SLICK MAGS... (120100)
From: Al Andersen <>
Subject: November #5 GTS Internet Update
Another thing about Slick 6364 Mags. You do need to fill out a 337 on them, unless things have changed recently that I'm not aware of. Since they are not listed on the original type certificate of the engine( Slick 664's are) (6364's didn't exist) they require a "Supplement" to the Type certificate (STC) to install on your C-145 or ( 0-300). Any STC is considered a "major modification" and therefore requires a 337 be on file with the feds. Since there are very few C-125's still out there, Slick never bothered to get the STC for the C-125, and a field approval 337 is required if you use them on the C-125. Most offices will not give you any hassle about a field approval on this installation, provided that they have someone who is familiar with the C-125/C145 similarities. They have the same accessory case, crank gear and cam gear as the C-145/ 0300. I like Slick Mags, and they are well worth the hassle of the paperwork involved in putting them on. -- Al Andersen