Sunday, March 1, 2009
What’s on the Horizon at Lycoming Engines
New iE2 electronic engine headlines series of recent programs that the Williamport, Pa.-based company is pursuing.
I love piston airplane engines and looking back through my logbook gives me a chance to remember all the types I’ve been fortunate to fly behind. I’ve flown with Pratt & Whitneys, "Shaky Jakes," Continentals, Lycomings, and, my personal favorite and most memorable, the Rolls-Royce Merlin. (If you’ve ever held the stick of a P-51 and felt the vibration from those 12 cylinders coursing through your fingers — well, it would be your favorite too.)
While I’ve loved every minute with every one of them, the one brand that has taken me more places and brought me back again has been the venerable Lycomings. And I’d be willing to bet that I’m not alone.
A bit of Lycoming history: the first flight of a Lycoming-powered aircraft was on April 3, 1929, when a Beechcraft TravelAir biplane took to the skies powered by a nine-cylinder, 215-horsepower R-680 radial engine. Obviously Lycoming got something right with the design, because the company eventually built some 25,000 of the engines over the following 20 years.
While 25,000 R-680s seems like a lot, that’s just a drop in the proverbial bucket when you consider that, to date, Lycoming has delivered over 325,000 piston engines and, according to the company, its engines are present in more than half of the world’s piston-powered general aviation fleet. Not bad for a company that started out making sewing machines.
As part of the Textron conglomerate, today’s Lycoming is a global leader in the engineering, manufacturing, assembly, testing and support of piston aircraft engines. The company produces a complete line of horizontally-opposed, air-cooled, four-, six- and eight-cylinder engines, including the only FAA-certified aerobatic and helicopter piston engines.
Understandably, the company’s employees are extremely proud of their accomplishments. Every engine they build today is still assembled by craftsmen who steadfastly follow the company’s 1940s slogan: "Build every engine as though you were going to fly it yourself!" Having been the beneficiary of some 200 million Lycoming-sponsored RPM’s, I’d like to pass along my gratitude.
While the company is committed to continuing its quality tradition, it is also striving to incorporate emerging technologies into its engines. The "next-generation" of piston power is taking shape in Lycoming’s Advanced Technology Center.
"I think the major announcements that we made prior to and at Oshkosh [in 2008] pretty much sum up the main items we are working extremely hard on right now," explains Mike Kraft, vice president of research, development and engineering.
By the end of last year’s Oshkosh AirVenture, the company announced five major programs: the iE2 electronic engine; the IO-233-LSA light sport engine; the first Echelon STC package for the Cessna 172 with the soon-to-be certified IO-390-AIA6 engine; the Thunderbolt turbocharged TIO-360-EXP engine for the sport aviation market; and a "mogas" approval program for the 360 series parallel valve engines. While all the announcements were significant in their own right, the one that will probably have the biggest long-term impact to the overall GA engine picture will be the iE2.
The iE2 is an integrated electronic engine — a technically advanced piston aviation engine that will set a new standard for piston engine controls. The first version of what undoubtedly will be a series is the 350-horsepower, twin-turbocharged, intercooled TEO-540-A1A.
"The iE2 is the number one ‘go’ program right now," Kraft says. "The main difference on this engine in terms of control is its ability to operate in a closed feedback loop, cylinder-by-cylinder basis. If you look at the old mechanical fuel injectors or carburetor designs, basically you had one big fuel control trying to distribute fuel to all cylinders on the engine. Those systems are very robust, but you end up with a compromise to accommodate all the cylinders."
"With the iE2, we have actually redesigned the mechanical engine to incorporate not just the ECU (electronic control unit), but what the ECU needed to control the engine," he continues. "This is not a ‘bolt-on’ system. There are no provisions for magnetos on the engine," Kraft says.
"It’s a ground-up redesign of the accessory housing on the back of the engine to remove unneeded components and add ECU instrumentation and power generation, a few items we had wanted to include in the engine. The cylinder jugs are modified to accept the new common rail fuel injection system. We also included knock sensors and some other types of sensor arrays."
Kraft explains that key to the iE2 engine is that each of the six cylinders will have an individually controlled fuel injection system, and that system is controlled on a closed feedback loop. With the TEO-540, for instance, there are six separate one-cylinder engines being controlled by the ECU.
"What that does," Kraft continues, "is allow you to reach a level of performance optimization that you cannot get with a single mechanical control on the engine in all phases of the flight profile — from transient takeoff and landing to steady-state cruise and all areas in between."
A certified ECU with the ability to close-loop control the engine gives designers a lot of latitude in terms of incorporating other new performance measures and efficiency capabilities down the road.
"For example, the detonation margin you need to have on the engine with a mechanical fuel system needs to be sufficiently large to ensure the performance of all cylinders under a wide variety of conditions," Kraft says. "When you go to an individual cylinder control you no longer have to design the performance for the aggregate of the cylinders so your margins on a per-cylinder basis can be less than what is required for the engine as a whole."
Kraft explains that this means that the engine can be run "at a higher efficiency point under all conditions. That’s a very large advancement in technology and capability."
"The architecture we have chosen for the iE2 and its ECU is also very modular," he adds. "So it’s not just a solution for a six-cylinder, twin-turbo engine, it’s a package that will work on a variety of engine types. It’s got a lot of transport into the future of engine designs."
Any discussion about next-generation general aviation engines has to involve what kind of fuel they will use. According to Kraft, this question has multiple potential answers. "The first thing we have to define is what ‘alternate fuel’ means," he says.
"One thing we know is that it is not 100LL aviation fuel," he adds, noting that Lycoming is involved with American Society of Testing & Materials (ASTM) Aviation Fuel Committee activities, which conclude that "100LL as a mainstream supply source is going to be at risk in the future."
"We did announce pre-Oshkosh, our ASTM D4814 standard, which is the automotive gasoline approval program for our IO- and O-360 engines capable of running on lower octane fuels," Kraft continues. "There are other aviation grade unleaded gasolines to investigate as alternate fuels and obviously there is the Jet-A route."
Kraft says that there does seem to be some promise in the market for a 100-octane replacement without lead, but the challenge is getting it produced and distributed in quantities that will meet the global need. Since Avgas for piston engines is just a drop in the global fuel market, doing that option economically could be the one thing that stalls the program even if it is technically feasible.
But all is not lost. The Department of Defense (DoD) "has basically petitioned the ASTM to create a lower octane unleaded aviation-grade fuel specification based on current refining practices," Kraft says. "There is a very large section of the operating fleet that would be satisfied by a lower octane unleaded aviation grade gasoline," he continues.
The issues with Avgas are one thing, but the "alternate fuel" that everyone is really talking about is Jet-A. Everyone that is, except Lycoming. Kraft says that while he can’t go in-depth about the company’s plans, "what I can say is that we are active. I think there are a large number of technical issues to close the loop with respect to using Jet-A in compression ignition piston engines, especially when Jet-A itself is now being derived from alternate sources and Lycoming is actively working on solving these challenges."
The uncertainty of what fuels will power our future piston engines is another reason why Kraft sees Lycoming’s new electronic controlled engines as being so important. "It will enable a whole new series of engines with a greater level of sophisticated, robust electronic control, enabling us to run an increasingly diverse set of fuels," he explains. "It’s not without question that the engine will be able to see which fuel is coming to it and adapt. Engines do that today in the automotive world. It’s a whole cascading set of enablers that you get from putting this kind of computing power on the engine."
Long Live the Piston Engine
While many aviation experts would have us believe that the piston engine is on its last leg, efforts by forward-thinking companies like Lycoming are proof that this is not the case. "The piston engine is hard to beat for reliability, fuel efficiency and total cost of ownership in the power ranges we talk about in general aviation," Kraft says. "I think the basic concept of the piston is going to be pretty robust for years to come."
One thing Kraft sees as changing is the way technicians will work on these next-generation engines. "Diagnostics — that’s one aspect of electronic controls that the current methods used by mechanics today will change," he says. "You are talking about an engine that can correct itself and to some extent have a lot of data stored to help diagnose a problem at a level that is just not available in the market today. It will change the way the A&P mechanics work on these new engines."
When it comes to learning how to diagnose, maintain and repair these new electronic engines, the best place to start is the Lycoming Engine Service School, which is at the Pennsylvania College of Technology. According to Jim Doebler, the school’s senior instructor, courses have been offered to mechanics, aircraft owners, teachers, home builders and piston enthusiasts for the past 15 years.
"It’s been a win-win situation," he says. "We get people from all over the world coming to the school. Plus, I take the school on the road — I’ve traveled around the world teaching the course."
Doebler says that since the school is virtually open to anyone who wants to attend, features more of an "informal" type course and does not involve a test at the end. "We’re giving out information. We teach how to read the publications, manuals, service letters — things like that," he explains. "Then we get into the meat of the engine. I start with the crankshaft and go through all the parts and details of the entire engine. When people know how things are made, they start to understand why there are things we do and things we do not do to the engine."
With the new iE2 electronic engine on the horizon, there will be quite a bit for even the most seasoned Lycoming technician to learn. "It’s going to be a real challenge for many of today’s aviation mechanics to get into these electronics — many of which, he has never seen before," Doebler says. "It’s basically new diagnostics like they do with cars. You just plug in a computer and get a diagnostic reading. Then they will just replace a component."
Of course, the computers can only do so much to tell you what’s wrong. You’ll still have to get your hands dirty. But Doebler stresses that although part of the Lycoming Service School will be taking a more ‘electronic’ direction, the basics of good engine maintenance will not change. "It’s not rocket science. The engine technology is basically 80 years old," Doebler explains. "We will still have to deal with weak cylinders and leaking valves, vibration problems and things like that."
The school’s curriculum will stick closely to its current, and very valuable, roots. "We not only tell you how to troubleshoot the engine, we tell you how to operate the engine properly," he says. "That’s a key point. So many people don’t understand how to do it."
"I run into people all the time who say they’ve been in the business for 40 years and there’s nothing we can teach them," Doebler says. "We also get those folks who say they’ve been doing something a different way than we teach for a long time. They don’t know they’ve been doing it wrong for a long time."
It seems like with piston engines and piston engine mechanics, the more things change, the more they stay the same.
For more information and to see a schedule for the 2009 Lycoming Service School, visit www.lycoming.textron.com/support/training/piston-engine-service-school.html