To burn fuel and oil you need a good spark. Quality magnetos are essential to a smooth running engine and to avoid electrical interference with your avionics.
What are the operating costs for magnetos?
In February of 2014, we had our Cirrus SR22TN magnetos inspected by an authorized service center, Inspect and Repair As Necessary (IRAN). They ordered parts and the labor for mag service was performed on site. The fly-out price was $1,095.
The magnetos should have been good for 500 hours, which would have been a direct variable operating cost of $2.19 per hour. But that’s not the way it turned out.
Summary Magneto Overhaul Expense
| Magneto Parts | 675.41 |
| Labor Rebuild LH & RH Mags. | 420.00 |
| Total | $1,095.41 |
| Expected Mag Life 500 hours | |
| Magneto Variable Cost Per Hour | $2.19 |
Several weeks later, we began experiencing static in the communication radio (Com. 1). By April, an increase in the popping static made Com 1 inaudible. At the time, the radio issue and mag inspection work seemed like unrelated events to us. We took our aircraft to an avionics specialty shop where a different authorized Cirrus service center just happened to also be on site.
They found a ground wire was loose on the Alternator 2 terminal and tightened the connection, but the interference was still present. The avionics shop began testing the Com 1 antenna and coaxial cable in search of a resolution. I’ll not post all the trouble shooting tactics, but needless to say, the problem was vexing.
Finally, the Cirrus authorized service center used a hand-held radio with headset to track the source of interference. With the SR22 engine running, a technician stood at the wing tip and listened on an open frequency. He moved toward the engine and the interference grew louder. With the hand-held radio antenna he checked engine components and identified the source of interference as coming from the left-hand magneto (“do not try this at home”).
Labor cost to trouble shoot the radio interference and find the faulty magneto was $856. But that’s not the end of the story. I’ll continued next week with “Part 2 – Magnetos Cost of Ownership.”
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