IGNITION SYSTEMS–The State of the Art, and Keeping Up With It

Once upon a time, aircraft ignition systems were simple, almost primitive components; airborne versions of the rough-hewn magnetos and spark plugs found in contemporary cars and trucks.

Times have changed. Although today's ignition systems can trace their roots back to those simple days--and many, in fact, do still use magnetos to spark engines into life--advances in materials, engineering, and design have brought aircraft ignition systems into the 21st century.

For aircraft technicians and mechanics, two names stand out: Champion Aerospace (www.championaerospace.com), and Unison Industries (www.unisonindustries.com). Between them, these two companies dominate the aerospace sector. However, as Aviation Maintenance discovered, Champion and Unison view aircraft ignition engineering in very different ways. To understand how their disparate approaches influence the aircraft you're working on today, and will be working on in the future, we need to look at each company individually.

Champion Aerospace: It's All About the Plugs

In 1903--while the Wright Brothers were working towards their first flight--the Champion Spark Plug Company was founded in Toledo, OH. Soon after, both Champion and the Wrights got off the ground. Within a few years, heavier-than-air powered flight was a reality, and Champion was making a name for itself supplying spark plugs and ignition components to the newly-born aviation industry.

A century later, the Champion Spark Plug Company is now known as Champion Aerospace, with its head office having moved to Greenville, SC. However, the company remains committed to the aerospace market; selling Champion-brand-name igniters, exciters, and leads for turbine engines; plus spark plugs, oil filters, and ignition harnesses for reciprocating engines.

In that time, many aircraft manufacturers have replaced magneto-driven sparking systems with electronic igniters. "However, the trend towards electronic systems supplanting magnetos is moving very slowly," said Steve Staudt, Champion Aerospace's aviation marketing manager. "The reason is that magnetos are a well-proven technology. Some may call them old tech, but the fact remains that magnetos are a mature, trusted commodity that get the job done."

With this in mind, Champion Aerospace is still focused on producing ignition sources for piston and turbine engines. But the company isn't sitting still when it comes to R&D. "We have several projects underway aimed at advancing spark plug design to a brand new level," said Alex Feil; Champion Aerospace's general aviation product manager. "They're still in the design and verification stage, so we can't go public with them yet."

Feil would allow that Champion's new sparking products are based on "thinking outside of the box" design, adding that "the whole plug" being created is radically different from anything that has gone before. "We're trying to create something that will literally deliver a `much bigger bang'," he related.

In the interim, Champion Aerospace continues to refine existing spark plug technology, to provide better, longer-lived, and more reliable performance for its aviation customers. "What we're focused on is ensuring the quality of our products are as high as they should be," said Staudt. "These means developing new plugs for the new engines coming onto the market, and coming up with variants like our 14 mm electrode design (the standard Champion plug uses a 18 mm electrode) that is catching interest in the market."

Since Aviation Maintenance is dedicated to helping aviation technicians and mechanics do their jobs better, we had to ask: What can MROs do to get more performance and life out of their existing spark plugs? On this point, Champion Aerospace had some intriguing answers.

"When it comes to spark plugs, people have a tendency to over clean the firing end," said Feil. "Not only do they damage the firing end from over grinding--which can crack the central insulator and distort how the ground electrode functions--but they ignore the rest of the spark plug in the process. When you clean a spark plug, you need to clean the whole thing. But do it carefully. If you damage the insulator and the electrode, the spark plug will misfire."

"People also have a tendency to over torque spark plugs when they install them, and to over-tighten the nuts on the ignition leads," Staudt said. "Both can result in damage to the spark plugs, which can lead to misfires and rough engine performance." To avoid this, Staudt recommended using properly calibrated torque wrenches to install spark plugs; in line with the Champion AV-6 service manual (available at www.championaerospace.com, or in book form from most Champion Aerospace dealers).

One last word of advice: "Technicians tend to assume that, when a piston or turbine engine runs rough, the cause has to be the spark plugs," said Staudt. "However, there are a lot of other factors that govern an engine's performance, including the condition of the wires, the power it's receiving, and the switching components that move the power around. So don't assume that it's the plugs; be sure to run a full set of diagnostics before you pull them out!"

Unison Industries: Taking the Whole Systems Approach to Engine Ignition

Unison Industries' roots only go back to 1980, but the company's heritage in aircraft ignition systems stretches back several decades to predecessor companies Slick Electro and Bendix Aircraft Ignition. Unison's relative youth may explain why this company--since 2002 a subsidiary within GE's Aviation business unit--has taken such a forward-looking stance on ignition system design and technology. Specifically, Unison focuses on creating a range of complete ignition systems for piston and turbine engines, for everything "from two-seat trainer planes and jumbo jets to the Space Shuttle," said Wayne Moles, Unison's marketing communications manager.

These days, the emphasis at Unison is on building smaller, lighter, and more heat-resistant ignition systems. This direction is in line with trends in the aerospace industry, said Scott Wright, Unison's department staff engineer for electronics. "Everywhere you look, aircraft designers are pushing for systems that provide better performance and fuel economy in lighter packages installed into smaller spaces," he advised. "If we didn't start downsizing what we make, they wouldn't fit into today's engine compartments."

To stay abreast, Unison's ignition systems are being redesigned to become higher density units. This translates into fitting smaller components into closer proximity, a change that requires higher heat resistance both from the ignition systems themselves, and in proximity to the other parts of the engine. "As engines become more efficient, they're getting hotter," explained Wright. "We have to work with that, which we are."

Beyond going smaller and lighter, Unison is working hard to deliver even more consistent performance from its ignition systems, many of which are electronic. "We patented solid-state exciter discharge circuits, which provide more consistent spark energy with each pulse than traditional spark gap units," Wright said. "And we patented electronic ignition architecture many years ago. In fact, one of our general aviation electronic ignition systems, the LASAR [Limited Authority Spark Advance Regulator], has been on the market for a number of years."

These days, Unison is working on creating smarter ignition systems, capable of not only performing self-diagnostics, "but self-optimization as well," he notes. "We are also making practical changes, such as reducing the length of ignition wires and placing ignition systems directly on engines."

As for advice to aviation technicians and mechanics, he said, "Thankfully, today's MRO professionals are being taught about electronic ignition systems at school, and taking the time to do so on the job through continuing education."

"So all I can really offer is for them to stay current, and watch out for new electronic ignition systems in the piston and turbine aircraft that are coming out today, and will be hitting the market in the future," he added

Implications for MROs

Clearly, the times are changing in aviation ignition technology, but this doesn't mean that the old systems are going to vanish any time soon. With airlines and business operators trying to wring as much life as possible out of their aircraft investments, MROs must maintain their ability to keep these machines flying, while staying on top of ignition systems advances.

So what does this mean for MRO managers? On the one hand, it is vital to keep your staff current with the latest in ignition system technology. On the other, it is crucial to maintain the technical know-how, equipment, and access to legacy ignition parts to keep all of your customers happy. One last point: Keep an eye out for new ignition systems that can be retrofitted into existing aircraft, to provide these aircraft with better performance and fuel economy, and your shop with more work to do.

For MRO technicians and mechanics, continuing education is a must. But don't let your existing ignition skills go to waste. Instead, try to become more knowledgeable and well-rounded in your approach to this element of aircraft maintenance. Not only will it make you better at your job, but it will enhance your marketability and--with luck--your pay!

The bottom line: Although spark plugs and ignition systems often play second fiddle to other, more demanding and finicky aviation components and systems, ignoring them can be a big mistake. Moreover, properly-maintained ignition systems will ensure top engine performance and optimum fuel economy, resulting in fewer AOG incidents and thus happier MRO customers. This is why it makes sense for MRO managers, technicians, and mechanics to keep their ignition knowledge skills hone and their knowledge up-to-date.