Carb ice, or more?

[Clip4]

Ah. Such a reliable source.

Their "view." That comes from a lack of experience and knowledge, not from any factual risks. Those same mechanics will blithely replace an engine, reconnect all the controls, fuel and oil lines, a far more complex job than opening a mag for inspection.

Slicks are easier to work on than Bendixes.

I suppose all this is your point of view and may be true, but last time I checked the people who operate the business determine the risk/reward not the customer.

Here is what an updated 2019 article in Aviation Consumer says.

IRAN v. Overhaul​

When your Bendix mags hit 500 hours in service, we recommend yanking them and sending them out to a specialized magneto shop for IRAN. For Slicks, we suggest getting an estimate for IRAN versus checking prices for rebuilt units—as they may be comparable and it can be faster to simply get rebuilt mags.

We do not recommend overhauling a magneto. To tag a magneto as overhauled, a shop must replace all of a specific list of parts, even if they are perfectly serviceable. Our research into prices showed it was generally twice as expensive to overhaul a mag as to inspect and repair and replace parts as needed. Depending on the parts that have to be replaced, we figure on $500-$700 for IRAN of a big Bendix mag—the smaller mags are less expensive. Bendix mags can be IRANed indefinitely. They do not need to be overhauled.

 

[Magman]

Mags are all the same; only different!

Anyone considering servicing mags would have little trouble with the

principles while switching from one brand to another.

However; that’s where it ends. There is very little interchange between

brands. Parts, tools, lubricants and techniques differ between them.

Even the screwdrivers and pullers won’t work on the other brand.


My take is this is a big factor in determining whether a shop will

work on mags, Buying tools, stocking parts and staff capability

training can be prohibitive if there is only a small volume of mags.

Shops such as Aircraft Magneto Service charge about $300 plus parts

fora 500 hour. I’ve never talked to anyone that was not happy with them.

 

[Dan Thomas]

We do not recommend overhauling a magneto. To tag a magneto as overhauled, a shop must replace all of a specific list of parts, even if they are perfectly serviceable.

And I don't, either. Definitions matter. From the "Interpretation" section of our Canadian Aviation Regulations, we see this:



And this:



A magneto inspection is an inspection, with replacement of defective parts such as points or condenser or distributor block or rotor. An overhaul returns a component to a status that makes it good for another engine life, i.e. 2000 hours. It requires more work, training and equipment than any inspection and adjustment. Just about everything other than the case and rotor gets replaced. It requires a test stand that drives the magneto to a certain RPM and measures spark distances. It becomes (in Canada, at least) Specialized Maintenance, limited to those shops and personnel that are certified to take it to that level. In the US, I don't think so. From the CARs:



This is the Slick magneto overhaul manual's list of parts that must be discarded and replaced with NEW (no recycled or salvaged parts) at mag overhaul:


Like I said, everything except the case, rotor and rotor drive gear. The "rotor gear" above is the plastic gear that drives the distributor rotor.

This is a magneto test stand, required for magneto overhauls. How often have you seen one in a GA maintenance shop?



For a lot of magnetos, the parts and labor cost for an overhaul can be much more than the cost of a new mag.

Once again, a 500-hour mag inspection IS NOT AN OVERHAUL. The magneto manuals make stark distinctions between them. They have the requirements for 100 and 500 hour inspections, and a whole separate section dealing with overhauls.

Anyone sending their mags out for expensive overhauls at 500-hour intervals does not understand the difference. They are wasting a lot of money for no good reason.

 

[Mikey52]

The guy that does our 500 inspections, uses that machine to test our mags before going out the door.

 

[Dan Thomas]

The guy that does our 500 inspections, uses that machine to test our mags before going out the door.

That's good, but not required by the Slick manual, and probably not by Bendix either. If the coil, points and condenser are good, and the E-gap properly set, the spark will be hot and the engine will start easily and have low mag drops on runup.

But if the guy has the machine, why not use it? Doesn't take long.