Slick Mag Inspections?

[CBogle]

Dear fellow members:

I have Slick model 6364 magnetos on my plane which are approaching 500 hours since new. My mechanic says that there is a service resommendation for an inspection of these mags at 500 hours, but, it might be just as cost effective to replace them as to have them taken off, sent out for inspection, etc.

My questions for the members are:

1. Since the 500 hour inspection is a recommendation and not mandatory, does it make sense to do? How likely is the failure of new mags prior to 1,000 hours? If one does fail, does the failure just result in the mag not working or can it break apart putting pieces in the engine, etc.?

2. If the concensus is that an inspection or replacement is advisable, is it better to just go ahead and replace? The mechanic thought that the total cost of an inspection would not be much less than replacement.

Thanks,

Curt

[Bruce Fenstermacher]

Curt

If you asked me last week I'd have had a different answer. But you might have seen the thread on my recent Bendix mag failure. It happened with 361 since overhaul which is unusual but it still can happen. i was luck and on the ground at idle. My mag seized due to bearing failure. I fell that had I been flying I'd have been putting it down with a pretty much shot engine after all the gears sheared off and ran through the engine not to mention any other damage to the plane from the forced off field landing.

So it's just not electrical failure that can happen.

Send them out for overhaul or worse replace them? Well if you have to do that I'm not buying them.

Buy your mechanics response it would seem he's not comfortable looking them over. I'd hunt around for someone who is.

[3958v]

Curt I don't know if this helps but mine started giving me starting problems at around 1000Hrs so I just replaced them. I was unaware of the 500 hr inspection. Bill K

[HA]

what Bruce said. Slick has a fine overhaul and inspection manual, even has pictures for those of us mechanics who are reading challenged. you do need a few special tools to do it right, any normally equipped shop should have the small tool kit. you have to have the tools to perform the maintenance that you claim to sign off, right? how many Slick mags are out there?

any mag should be opened up at 500 hrs, doesn't mean you'll find big problems but it's preventive maintenance. heck, my Bendix mags are so old they still have the phenolic gears - no problems so don't need to replace them yet, maybe next time. what I always tell folks is, (say it together) if your car breaks you just pull over to the side of the road. if your airplane breaks, well that's not always convenient.

so, after all that, I'd recommend you find a mx organization that can do the basic magneto maintenance that you should have done and then you can go on about your business knowing that the i's are dotted etc.

just 2 cents worth from a guy who used to maintain a lot of farm country airplanes, like being a prophet in the wilderness sometimes

[blueldr]

Curt,

You need a new mechanic. Inspecting a mg is pretty basic and you do not need a special test bench for the inspection.

[Dave Clark]

Curt,

You need a new mechanic. Inspecting a mag is pretty basic and you do not need a special test bench for the inspection.

There is a lot more to it than meets the eye Dick. Even though I have rebuilt and inspected mags I now prefer to leave it to a a magneto expert. Remember, spark + fuel and it should keep running. My favorite is Cliff Orcott:

http://www.aircraftmagnetoservice.net

I've been using them for thirty years. Not the cheapest but by far the best. My mags are there now in fact. Call and talk to them about it.

[Metal Master]

I have been a Professional aircraft mechanic for thirty six years. I have run shops with 16 technicians at a time. I made sure that each new hire learned to do 500 hour Inspections on Magnetos and Alternators. With each individual I would go through each Magneto Type or Alternator that we would inspect. I did this because it was at the time the most cost effective way to assign work. The last pace I worked for 17 ½ years had 49 charter, lease back and rental aircraft with every type of ignition system that was made be it Bendix or Slick Eiesmen Case tractor & some real weird mags on a TD9 Caterpillar tractor. Needles to say I have formed many opinions over the years. Most of which no one listens to and my opinions have changed over the years.

Eventually I hired a full time accessory over haul guy. It was cost effective because he could do three mags to one of my line mechanics. We replace all hardware screws, & seals on each 500 hour inspection. Why because the lock washers loose there tension and then the screws back out with vibration even if the torque was set properly. It cost about $2000 dollars annually to Certify all of the shops as well as the individual mechanics torque wrenches which I paid for. This insured that all work would meet standards. I ca tell you most shops will not pay to have there mechanics torque wrenches certified. We had many specialty Torque wrenches such as the one torque screw driver we had just for Magnetos.

I have had brand new Impulse couplings break springs after only 50 hours of operation in both Bendix & Slick mags. Bendix Mags do put out more spark energy. This is generally because of the larger coils I assume. I do not care because both mags run well in the application to which they are applied as long as they are maintained properly. That is not to say that I do not prefer one mag over another. I Like Slick Mags particularly for the ease of maintenance. They are easy for the average technician (Read Mechanic) to learn to repair and troubleshoot. The entire Mag family follows the same design. However I prefer the large Bodied Bendix mags and shower of sparks ignition in high altitude flying airplanes. Preferably with the Mags pressurized. Such an installation might be in a Cessna 340 or 421. Ram aircraft supplies pressurized slick mags with there Ram converted engines. They like them well. I do not. The vents on the mags plug with carbon about every fifty hours and it can not be cleaned with out removing the mag. They need to be removed about every 200 per service instructions to have an internal inspection. I can tell you if it is not done you will be purchasing a new mag at the 500 hour because the inside of the mag will look like it came off of the Titanic off of the bottom of the ocean. Large bodied pressurized Bendix mags do not have this issue. I could go on as to why but will not here.

The reason I say all of this is because from all of these issues people form generalized opinions about mags. This often leads to generalized statements that can be misleading about one product line or another.

So I will make some generalized statements that might be misleading:

• A few years ago Bendix came out with a service bulletin that lead to an AD. It required that the Coils be replaced. At the time Slick was offering a trade in allowance (Trading in Bendix mags) that made the purchase very cost effective. A lot of people switched to Slick mags.
• Part of the reason for this is because in either case of Slick or Bendix mags if three major parts such as a Distributor block, coil, and bearings had to be replaced with labor included you quickly exceed the purchase price of a new mag.
• Most mags do not need to have all of these parts replaced at a 500 hour inspection in most cases. So it is generally cost effective to do a 500 hour inspection on a mag. If you follow the 500 hour inspection and only the 500 hour inspection guide lines.
• If a technician spends the time to do a 500 hour inspection and the mag ends up being replaced. Then the profit price of the new mag will not cover the labor spent inspecting the first mag. It is easier and more cost effective to just replace it. But you do not know that going in. I try to explain all of this up front to a customer. But it still does not always help
• Customers do not like paying to have one mag inspected at a great cost and then have it replaced at an equal or similar cost. And have to pay for both.

• Most auto parts are marked up 200 % at the dealer and service shops. Most aircraft parts are only marked up 15 to 25 % at shops. They are still costly. Most owners squeal.

• I do not run that business any more it is to stressful.

• On my airplane I have Bendix Mags which are freshly overhauled. I know how and have the tools to overhaul Bendix mags. I have done lots of them 100’s. I had my friend and previous employee overhaul my mags for me. He has his own business now. Magnetos Inc. I bought the parts he did not charge me for labor. It still cost me nearly $500 in parts. Why did I rebuild the mags? Because I trust Cliff, I know what’s in the Mags. They were what were already installed on the aircraft. I have had brand new mags fail internally and destroy an engine. If I had had slick mags I would have kept slicks.

• I would not make a general sort of statement that because a mechanic does not do mags that he does not know what he is doing



And you thought George was long winded.

Jim

[Bruce Fenstermacher]

• I would not make a general sort of statement that because a mechanic does not do mags that he does not know what he is doing
Jim

While my statement could be taken this way it is not what I meant. A mechanic can have many good reason why he won't work on something. There are lots of mechanics that will service mags and will do a good job.

When making a consideration of this type one must always factor in the economics. Perhaps that is what Curts mechanic is trying to tell Curt.

Jim your whole post was very good thanks.

[Metal Master]

Thanks Bruce,

Jim