Magnetos

[Hans]

Question:
I own a 2004 DA-40...purchased it in 2012 with 80hrs on it...I currently have about 400hrs on it now...it has been a GREAT plane very little trouble...my question is when do I replace magnetos ?? I do not have any problems, rpm drop is fine, fly with fine wire plugs and Gami injectors...I know there is a "suggested" time, but Idon't want to spend that kind of money with-out knowing...and is new better than re-furbished ? Should I also do the wire harness too ?
Thx

[Steve]

I replaced mine with new at 534 hours, 12 years. New harness at the same time. Had the old ones rebuilt, have them in the hangar as spares. I was following the conventional wisdom to rebuild/replace at 500 hours. Mine were working well at the time.

Having said that, magneto failures often don't give much, if any, warning.

Steve

[Hans]

Do you remember cost ??
Thx

[Steve]

I bought the new ones from Sky Supply:

1 4347
Champion/Slick 4347 Magneto
Refundable Core Deposit $150:
I do not have a LIKE core to return
$1,090.50 USD $1,090.50 USD

1 4370
Champion/Slick 4370 Magneto
Refundable Core Deposit $150:
I do not have a LIKE core to return
$986.42 USD $986.42 USD

I rebuilt the old ones so I didn't get the core charge back.

The rebuild invoices are below:

[Hans]

-So with the wiring harness figure about 2k?
Thx

[RMarkSampson]

The Slick Magneto in my DA-20-C1 has a 500 hour inspection requirement. You won't find much information in the Diamond literature - need to consult Continental Engine Manuals. Since I'm a DA-20 owner so I refer to the Teledyne Continental Motors IO-240-B Maintenance Manual. They also have a M87-16, Slick Service Bulletin SB1-86A which discusses Magneto Servicing.

I do not replace every 500 hours - I have a professional do an IRAN (Inspect, Replace as Necessary). Mike Busch (GA mechanic that provides great advice, who was at the AOPA fly-in in Tampa this past weekend) solidly recommends having the IRAN done every 500 hours. You can shop around for a reputable service facility. About two years ago I used Tropic Air in Indiantown, FL - close to me so I actually visited them to drop them off and "inspect their operation." They gave me the grand tour so I knew exactly what they do when they service a magneto. Slightly over $1000 to have both mags done - they come back looking new, with new points and other wear items replaced. If they do need to be replaced, they will tell you...

[smoss]

Getting new ones is definitely the quicker way to go, but there are a few gotchas. First, getting the drive gear off (not included with new mag-the old one is re-used) is evidently quite difficult, and depending on the skill of the mechanic may be quick, or quite painful with some abuse to your gear. If you have your own mag rebuilt instead, the drive gear stays on. Second, while you may think a new mag is safer, a brand new mag soon after installation may have a service bulletin come out, such as Slick SB 1-15, explaining that the distributor gears on the whole bunch manufactured from 11/2013- 7/2014 are subject to failing prematurely.

[ricksigler]

Hans,

I did my mags at about 600 hrs. I used Aircraft Magneto Service in Montana. The mechanic took the mags out and I sent them for service. I seem to remember paying about $800 to $900 for both to be done. Very quick turn around and great service. I think there's a thread on the forum that discusses mags in detail.

Rick

[Rich]

This 500 mag deal is an IRAN. I've had it done 3 times. The first two were done by American Magneto Service. When I had the first one done, he was at Boeing Field in Seattle. I took the mags down and he actually did the work while I was there. He was showing me what he was doing as he was going through it.

The second time was also done by AMS. At that time he had moved to Vashon Island.

The third time was done by Premier in Troutdale in conjunction with extensive engine repair they were doing in '15. The line item is stated as "500 hour inspection".

Basically they check for wear items, slop in the bearings and the gears, test the coils, set internal timing, apply some lube. There are some specialized instruments used in the process.

[Don]

When you guys are referring to engine hours, are you stating Hobs or TT hours?