The return of Cessna Aircraft to the piston aircraft market is undoubtedly the most tangible result of the general aviation statute of repose legislation that was passed in August 1994. As AOPA General Counsel John Yodice points out in this month's " Pilot Counsel" on page 126, it's still too soon to know for sure the long-term effect of the legislation on the industry that it was designed to help.
Although that gleaming new Cessna factory on the Kansas prairie has become the symbol of general aviation revitalization, the signs of an improving industry are all around in the form of increasing aircraft sales and component manufacturing.
One of the most unusual results of the legislation, however, is not a new airframe or engine or a new company entering the market. Instead, it's new technology for magnetos — the ancient but fairly reliable aircraft ignition systems that pilots love to hate.
In the fall of 1986, I attended a Senate hearing on a bill designed to provide general aviation tort reform. The bill was one of many that would be written and rejected over the years before the 1994 legislation was signed into law.
At that hearing, Rick Sontag, president of Unison Industries, told the legislators that his company had developed a new generation of ignition system for piston airplanes — one that promised many benefits. However, the project had been shelved out of fear that any changes or improvements to the tried and true magnetos might suggest to trial lawyers that the existing product was unsafe — opening the door to even more lawsuits. As it is and was back then, Unison, which manufactures Slick magnetos, along with many components for turbine engine ignition systems, is often sued when an aircraft crashes. Even in cases when the mags obviously played no role in the accident, Unison becomes a target in the trial attorneys' shotgun approach at trying to get a settlement out of someone.
"Ladies and gentlemen, until some measurable tort relief is granted, I can promise you that Unison Industries will not be introducing those new products," Sontag chided the senators.
And, in fact, the company did not introduce its new products until after the legislation passed. Finally, in 1996, the LASAR ignition system debuted, bringing with it the potential for improved performance or fuel savings and simpler engine management. In reality, LASAR is not the system Sontag referred to in that Senate hearing 10 years earlier; it is actually a much enhanced system, according to Brad Mottier, Unison's senior vice president.
The shelved system was an electronic replacement for the conventional magnetos, while the LASAR is a microprocessor-controlled add-on to mags. The never-produced system was far less capable than LASAR, according to Mottier.
The good thing about mags is that they are simple, relatively inexpensive and reliable, and they operate even if the aircraft's electrical power supply fails. The bad thing is that they are stupid. In their electromechanical brains, the engine has only one setting — full power. During takeoff the engine hums along at near peak efficiency because the mags are firing the spark plugs at the optimum time for full power. At startup, taxi, and during cruise at less than full power, though, the mags keep firing those plugs at the same timing as that at takeoff. As a result you have an engine that's hard to start, cranky during taxi, and less efficient at cruise than it could be — all in the name of mechanical simplicity.
Enter LASAR, which gives magnetos an instant Ph.D. LASAR measures manifold pressure, cylinder head temperature, and crankshaft speed (rpm) and position, then selects the optimum ignition timing angle and spark energy from a three-dimensional chart stored on a microchip. The controller then signals the mags when to initiate the spark; it also controls the power and duration of the spark to optimally ignite the fuel in the cylinder.
To create the electronic charts that the LASAR looks to for guidance, Unison spent years testing various engine models on dynamometers and in actual airplanes.
What the pilot gets is an airplane that starts more easily, runs more smoothly during taxi, and provides better climb performance. During cruise, the pilot can choose to have slightly greater power, thanks to the more efficient operation of the engine because of proper firing of the plugs. The alternative is to operate by using the same power as before, but to use slightly less fuel in the process. Unison reports that its dynamometer tests show that LASAR-equipped engines deliver an 8- to 14-percent improvement in fuel economy compared with traditional magneto-equipped aircraft.
However, the real world is not a dynamometer — so, as they say, your mileage may vary. More likely, what you'll see is a 3- to 4-knot increase in cruise speed or a half gallon or so reduction in fuel burn. In climb, expect a couple of hundred feet-per-minute improvement. In general, the higher the aircraft flies and the lower the power setting, the greater the impact of the LASAR system.
As a result of the greater power potentially produced and more efficient burning of fuel, cylinder head temperatures may rise 10 degrees Fahrenheit or so. In most circumstances, this is not an issue because typically aircraft engines run well below their maximum CHT limit during climb and at or below the factory recommended maximum cruise CHT. For example, despite worst-case tactics used in testing, Unison could not get the 172 to exceed or even come near the CHT redlines.
Nonetheless, the FAA worried that the greater CHTs might be a problem. To deal with the issue, Unison put the electronics to work at further managing the spark advance controlled by the LASAR.
The system continuously measures CHT and CHT trends and compares them to limits stored on its microchips. As limits are approached, the system automatically changes the spark advance to make the engine run cooler — or less efficiently, if you prefer.
For all these smarts, you can expect to spend about $2,500 for a system that includes two new mags (traditional mags cannot be modified to work with LASAR); the controller, which is about the size of a cigar box and is attached to the firewall; a low-voltage control harness used to carry commands among the various LASAR components; and a high-voltage output harness, which is identical to the harness used with traditional mags.
The thing that makes the Unison attorneys smile, along with their comrades at the company's liability insurance firm, is LASAR's method of failure. If the system quits as a result of component failure or loss of electrical power, you're flying an aircraft with a pair of stupid mags. As we know from decades of experience, even that beats driving. However, if the system does fail, you probably won't be able to start the airplane again without repairing the LASAR because the new mags have no impulse coupling to aid in starting.
At present, Unison has obtained approvals to install LASAR on Lycoming O-320s, and parallel-valve (180 horsepower or less) O/IO-360-series engines. Additional models of both Lycoming and Continental engines will be approved soon, according to Mottier. LASAR cannot replace dual mags — a pair of mags in one case driven by a common shaft.
Although LASAR is just now reaching the market in volume, Unison has not retired its R&D team. Instead, they have developed another new product with even greater applications. SlickStart promises to ease engine starting. The small box is mounted to the firewall. Connect power from the battery, ground it, and run a wire to the left mag's P-lead. During startup, SlickStart drastically increases the spark voltage — as much as 340 percent greater than is provided with traditional impulse couplings. The result is nearly instant starting, regardless of conditions. SlickStart measures the spark produced by the mag and boosts it as necessary to assure starting. In addition, SlickStart provides many sparks at the appropriate point in the start procedure, rather than the one spark traditionally supplied. All the pilot has to do is to provide the proper mixture control. Even SlickStart is no match for poor priming technique. As soon as the ignition switch is moved from the Start position to Both, SlickStart shuts down, its job done for the flight.
Faster starting can reduce battery and starter wear and, most important, the frustration factor of operators.
Unison plans to introduce SlickStart this month at Sun 'n Fun in Lakeland, Florida. Suggested list is $350. The unit is compatible with virtually any mag except dual mags.
So, if you think that the statute of repose was a one-trick pony in the form of Cessna's returning to the piston-engine market, think again. Unison is just one company that has persevered through GA's doldrums and is now poised to bring new performance and efficiency to the fleet, thanks to some well-reasoned legislation.
