SureFly, the Electronic Ignition, and the Hundred-Year-Old Magneto Finally Meeting Its Replacement in the Oshkosh Exhibit Hangars

At AirVenture Oshkosh, one of the quietest exhibits is also one of the most significant: a small electronic ignition module that is beginning to replace the magneto, a piece of aircraft technology that has barely changed since 1918. Electronic ignition systems - led by SureFly’s Spark Ignition Module (SIM) - deliver a hotter spark, variable timing, easier starts, and a few percent better fuel burn, while a retained magneto still provides the electrically-independent backup that has kept piston engines running for a century. As of July 2026, these systems are certified and shipping for a growing list of Lycoming and Continental engines.

What is an aircraft magneto and why has it lasted 100 years?

A typical piston single carries two magnetos, bolted to the back of the engine and spinning off the accessory case. The defining feature is independence: a magneto makes its own electricity. It spins a magnet past a coil, builds high voltage, and fires the spark plugs without any help from the battery or alternator.

That is why you check the mags during run-up - turning the key to each one and watching the RPM drop - and why the engine keeps running even if the entire electrical system fails in flight. If the alternator quits and the battery dies, the magnetos never cared about them in the first place.

This was brilliant engineering for its era. In 1918, with no reliable aircraft battery and no trustworthy alternator, a self-powered ignition was the only sane way to keep an engine lit. The magneto solved a real problem so well that we are still flying it.

Why does the magneto need replacing?

The magneto solves a 1918 problem and carries 1918 compromises. There are three main ones.

Fixed timing. A magneto fires at a fixed point, usually 20 to 25 degrees before top dead center. That timing never changes - it is the same at full takeoff power as it is when leaned out in cruise at 8,000 feet. But at low power and altitude with a lean mixture, fuel burns slower and the engine would prefer an earlier spark. The magneto cannot provide it.

Mechanical wear. A magneto is full of moving parts - points that open and close, a rotating magnet, bearings, a distributor cap, carbon brushes. All of it wears. That is why manufacturers call for inspection at 500 hours and overhaul at engine overhaul. Points erode and timing drifts, making a tired magneto one of the most common squawks a piston mechanic sees.

Weak spark at low RPM. The magneto’s spark is relatively weak, and it gets weaker the slower the magneto spins - exactly when you are cranking a cold engine on a frosty morning and need a strong spark the most. That is backwards from what you want.

How does aircraft electronic ignition work?

Electronic ignition brings the concept that has been in cars since the 1980s to the certified aircraft engine. Instead of a spinning magnet and mechanical points, you get a crankshaft position sensor, a small computer, and a solid-state coil that delivers a much hotter spark. There are no points to erode and no mechanical timing to drift.

The performance advantage comes from the computer. It knows engine RPM - and in more sophisticated systems, manifold pressure too - so it can vary ignition timing. It advances the spark when the engine wants it advanced (up high and leaned out) and pulls it back for takeoff, doing the exact thing a magneto physically cannot.

Operators running variable-timing electronic ignition typically report a few percent better fuel burn in cruise - roughly half a gallon to a gallon per hour on many four-cylinder engines. They also see easier starts, smoother running when leaned aggressively, and spark plugs that foul less because they are fired harder and cleaner.

What is the SureFly SIM?

The best-known product in this space is SureFly, with its SIM (Spark Ignition Module). Its traction comes from a smart certification path: SureFly built the SIM as a direct replacement for one magneto, using the same drive, mounting pad, and footprint. You pull one mag, bolt on the electronic unit, and keep the other magneto in place.

SureFly earned a Supplemental Type Certificate (STC) across a long list of Lycoming and Continental engines, and it sells an experimental version too - which is why you see it on so many homebuilts out on the flight line.

Why run one electronic ignition and one magneto?

The typical setup today is one electronic ignition paired with one traditional magneto, and that hybrid is deliberate engineering.

The honest weakness of electronic ignition is that it needs electrical power. The solid-state box does not make its own electricity the way a magneto does. Run two electronic units, lose your whole electrical system, and you have a problem - the exact scenario the magneto was invented to survive.

The hybrid answer is elegant. The electronic unit gives you the hot spark, variable timing, better fuel burn, and easy starts. The remaining magneto sits there as an independent backup, making its own power, ready to carry the engine if the electrical system quits. SureFly also builds an internal backup power source into the SIM so it can ride out a brief electrical hiccup on its own. Belt and suspenders.

What are the downsides of electronic ignition?

This is not a free upgrade, and the trade-offs are real.

Cost. Expect a few thousand dollars for the unit, plus installation. On a certified airplane you are paying a mechanic and living inside the STC’s approved list - and your airframe-and-engine combination has to actually be on it.

Added dependency. A magneto is beautifully dumb. An electronic ignition is a small computer with sensors, connectors, and a power feed - every one a new potential fault point. The reliability record so far has been genuinely good, but this is a newer system with fewer decades of field history than the magneto.

Modest fuel savings. If someone claims the box pays for itself in a year, do the arithmetic on your own hours first. For a pilot flying 50 hours a year, fuel-based payback takes a long time. The stronger arguments are easy starts, reduced maintenance from deleting one magneto’s overhaul, and smoother lean-of-peak operation.

Timing is not a toy. Variable timing changes when peak cylinder pressure occurs. Done right within approved limits, that is a benefit - but too much advance at high power causes detonation, and detonation damages cylinders. This is precisely why certification matters: approved installations lock the timing curve to what the engine can safely take. This is not a place for improvisation.

Is the aircraft magneto going away?

Not quickly. Electronic ignition is not vaporware - it is shipping now, and you can buy one this week at AirVenture. The experimental world has run it for years, and the certified world is catching up one engine model at a time.

The direction of travel is clear: the magneto is on a slow glide toward retirement. But slow is the operative word. There are hundreds of thousands of magnetos still flying, and they will keep flying for decades - because they still work, and because certification moves at its own pace.

That progression is Oshkosh in miniature. The experimental crowd proved the idea first, out on the flight line, on airplanes built in garages. The certified manufacturers then show that the idea has matured enough to bolt onto a factory airplane. The experimental hangar is the laboratory; the main exhibit hangar is where the lab results grow up and get a paper trail.

Key Takeaways

• A magneto makes its own electricity, which is why a piston engine keeps running after total electrical failure - its greatest strength and the reason it has survived since 1918.
• Electronic ignition (like the SureFly SIM) adds variable timing and a hotter spark, delivering easier starts, less plug fouling, and roughly 0.5–1.0 gallon per hour better cruise fuel burn on many four-cylinder engines.
• The smart configuration is a hybrid: one electronic unit for performance plus one magneto as an electrically-independent backup.
• The real payoffs are easier starting and lower maintenance, not dramatic fuel savings - payback on fuel alone is slow for low-time flyers.
• Electronic ignition is certified and shipping for many Lycoming and Continental engines, but the magneto will remain in service for decades.