Engines

Back in the day when aeronautical engineers actually wore ties-skinny black ones-and ran calcs on wooden slide rules, it was accepted wisdom that to develop a new airframe and fit it with a new, untried engine was to court disaster. Diamond Aircraft proved the point in the digital age with its DA42 Twin Star. The Twin Star proved a terrific airframe and a strong seller. But the four-cylinder Thielert diesel engine Diamond selected as the powerplant turned out to be just the disaster the guys in the skinny ties worried about. Owners complained of high maintenance incidence, long downtimes and last spring, Thielert went bankrupt, beaching hundreds of owners who needed parts and engines. Moreover, during its initial recovery, Thielert quoted parts and replacement engine prices that raised hourly engine reserves to $100 or more-per engine, without fuel. Although Thielert seems to be getting back on its feet, Diamond went its own way and established the Austro Engine Company in Wiener Neustadt, Austria, next door to Diamonds factory. After what must be one of the fastest engine development cycles in recent history, Austro announced in late January that it has EASA certification for its 168-HP AE 300 diesel engine and production is already underway. (AE 300 is the marketing nomenclature; the type certificate calls the engine the E4.) The good news for Twin Star owners stranded by Thielerts cratering is that in the Austro, they now have a choice in replacement engines. The new engine delivers more power and is more fuel efficient, according to Diamond. The bad news is that it will be a number of months before retrofits are available for Twin Stars and the single-engine DA40 TDI. Diamonds Peter Maurer told us in February that the factory has the capacity to produce replacement engines for existing DA42s or soon will. But the initial production will go to new DA42 NG models (next generation) not to retrofits because Diamond wont have approvals for retrofits until later in the year. Meanwhile, certification work on the Lycoming-powered version of the DA42 is nearly complete, so owners may soon have the option of three engine choices.

It was the best of times, it was the worst of times. Were not talking about Dickens 19th century London, but last week in the used aircraft market. Its the best of times if youre looking for a late-model used aircraft of any kind, the worst if youre trying to sell anything for top dollar. Stated another way, if you made a note to yourself to start shopping for a used model with glass after theyd been on the market for five year, now would be a good time. The market is awash with good deals on recent model aircraft and many of them have full glass for under $200,000-the downward pressure on prices is obvious. High inventories and brokers willing to wiggle improve buying prospects.For this article, were focusing on entry level four-place cruisers, specifically the Cirrus SR20, the Cessna 172, the Piper Archer and the Diamond DA40 Star. There are even better deals in the step-up Cirrus SR22, but we’ll focus on that later. About five years ago, brokers we occasionally talk to surmised that as Cirrus, Cessna, Columbia (now Cessna), Diamond and others pumped new aircraft into the market, this flood of new airplanes would inevitably put downward price pressure on the used fleet. We seem to have crossed this dividing line, thus the used models that had been appreciating or holding their value, now no longer do. Values of older used aircraft havent yet paralleled the sort of depreciation thats standard for cars, but with fewer buyers, they simply don’t retain value as they once did. The trend seems to represent an unusually good buying opportunity for owners looking to upgrade to something newer. Some surprisingly recent model aircraft are selling for prices we wouldnt have dreamed of two years ago. For our purposes, “recent” means 1997 forward-thats the year Cessna came back into the market. Two years later Cirrus introduced the SR20, then Diamond rolled out the DA40 Star.

Start with a heaped serving of ignorance, add equal measures of industrial inertia and mediocre engineering, add a dash of petulant, not-invented-here intransigence and you’ll have a lucid understanding of how the airplane industry looked at the mundane world of engine management 10 years ago. Or, more accurately, how it looked at engine leaning. Five years before that, General Aviation Modifications, Inc. had begun marketing its calibrated fuel injectors to wide market acceptance. Along with that, came the old-new idea of running engines lean of peak EGTs to save fuel and tame high CHTs. Reaction from the entrenched interests was harsh. you’ll fry the cylinders, said Lycoming. you’ll fry the valves, said mechanics. you’ll fry everything, said some engine shops. What was needed was a controlled experiment whereby a fleet of airplanes running lean of peak could be carefully monitored. Yes, we know the orginal Piper Malibu specified lean of peak, too. But its engine service history was spotty, probably for reasons not related to leaning. When it introduced the SR22 TN in late 2006, Cirrus provided a better lab rat because every SR22 has sophisticated engine data monitoring. Here was an airplane whose POH required lean-of-peak operation. It was nothing if not a bold stroke.

The companies that sell aviation oils tend to view their products as being like Mother Nature-and you don’t mess with Mother Nature. Which is another way of saying that if they thought their oils needed a certain additive package, they would put that package into the product. It stands to reason, then, that if an oil company doesnt use a certain additive, you don’t need it. The fault in this logic is that its manufacturer-centric-it assumes that whats good enough for the oil company should be good enough for you. And if an oil maker doesnt use an additive simply because it costs too much, thats a marketing decision the customer would be ignorant of, not a technical consideration. This more than anything explains why the oil companies have been chilly toward an additive we think is promising-ASL CamGuard. Our bench tests of CamGuard have proved promising, especially with regard to corrosion prevention, which we are increasingly inclined to believe is the more critical consideration than running wear. We recently performed an informal in-service test of CamGuard and were reporting on a more extensive test done by our AVweb colleague Mike Busch in his Cessna 310. His findings mirror our own.

A friend lent me his August issue of Aviation Consumer because he knew Id enjoy reading your article on Tri-Pacers. Actually, I own a 1962 Colt, pretty much stock, although it was recovered for the second time five years ago. The previous recover was in 1973, before I owned it. With fabric still airworthy, my concern, as you pointed out, was what lay beneath it. We actually found very little structural rust and corrosion, so the restoration was a picnic and I enjoy flying it once again. Two things pop out in your article. First is the disparity in the current price range for airworthy Tri-Pacers, which your article stated as between $15,000 and $20,000. Ive been seeing prices between $25,000 and $30,000-plus. A little more research might be in order. Second is the phone number to contact Eleanor Mills, membership officer of the Short Wing Piper Club, who has recently moved to Springfield, Missouri. The number is now 417-883-1457 or e-mail swpn@sbcglobal.net. I heartily recommend the group. Their bimonthly news magazine alone is worth the price of admission.

Although we didnt expect to see it, that great summer sweat-fest that is EAA AirVenture yielded some powerplant developments that were both eye catching and encouraging. (And neither did the sweat materialize; Oshkosh was unseasonably cool and dry for the entire week-at least by our standards.) We saw three significant developments that are worthy of note: Lycoming came out of the ground with not just a new engine, but an entire suite of new developments that represents a fundamental sea change for a company that has been technologically somnolent for at least a decade. Diamond says its serious about its Austro engine project and it meant to show it with a production mock-up of the new AE 300, which its driving forward to certify in Europe before the end of the year. Austro is essentially looking to become the next Thielert-but without the financial implosion-and its doing so at a breakneck clip. We got our first detailed look at the engine.

There is no shortage of aircraft engine overhaul purveyors out there appealing to a number of aircraft owners who are interested in engines with something special-something that says, “My engine is better than the run-of-the-mill overhaul.” Extras may mean outside flash, special parts, alleged attention to detail or tighter measurement tolerances. Plain, factory engines regularly make TBO, and problems en route to TBO are not often those that a custom engine build would address. Those are long times between overhauls and low utilization that cause corrosion, a cracked cylinder from a metal defect, or improper leaning technique leading to burned valves. Custom overhauls come with claims for more horsepower, greater reliability, smoothness or all three. In our view, the validity of these claims depends on the integrity of the shop, the size of your pocketbook and the seat-of-your-pants feel.

In the four years since our last survey (May 2004 Aviation Consumer), several things have changed in the world of engine overhauls. Teledyne Continental Motors (TCM) and Textron-Lycoming have both pumped up their marketing of zero-timed and factory-overhauled engines. Engine and cylinder rebuilders have expanded their presence with both Engine Components, Inc. (ECI) and Superior Air Parts offering complete engines to the experimental market. Superior is even certifying their Vantage engine to compete with the Lycoming O-360 and IO-360. For all thats changed, however, the long-term viability of your new engine will largely depend on the quality of your cylinders. Is it a better road to use aftermarket cylinders like Superior Millenniums or ECI Titans? Or is it a safer bet to go with the OEM product?

Give pilots and aircraft owners credit for one thing: It takes a strong constitution to remain functional and focused when the avgas truck creaks to a halt and you realize that what you thought was a 5 on the price placard at 100 yards was actually a 6. So you whimper softly and pay the man, perhaps salving yourself with the idea that the new Jet-A burning airplanes will make this nightmare go away. But will they really? Are diesels that much more efficient than gasoline engines? Yes, possibly. But it depends on the engines being compared. When it comes to efficiency, Lycoming and Continental are not created equal. But the larger issue-and whats driving the Jet A piston revolution-is that Jet A-burning pilots (piston or turbine) neednt get their pants snagged worrying about their fuel being phased out in 10 years. They can also count on it being available in every country on the planet and at ever more airports. And thats why we write stories about Jet A piston engines, not because theyre cheaper to operate-they can be-and not because theyre more efficient-they are, but not as much as you might think.

What exactly is the difference between a factory rebuilt, a factory overhaul and a field overhauled engine? And is opting for the factory version worth the extra money? As the engine overhaul business has become ever more competitive, there’s even more confusion about the difference between categories and sources. Hardly a month goes by when someone doesnt phone to ask: “here are the numbers the shops are giving me. What should I do?”

FADECs for piston engines-full authority digital controls-are an idea whose time seems to stubbornly refuse to come. Even though theyve been around for a decade and everyone seems to concede they make sense, buyers havent exactly clamored to turn ove engine operation to a black box on the firewall. Diamond and Thielerts impressive success with the TAE Centurion 1.7 diesel represents the high water mark for FADEC, since the 135-HP turbodiesel relies entirely on electronic control, with no mechanical backup of any kind.

Doctors learn that a certain bedside manner is helpful when conveying bad news to a patient. Airplane mechanics-at least the ones we know-don’t necessarily feel the same obligation, thus when catastrophe looms large during an annual inspection, you might hear, Hey, we found a crack in your case, youre hosed. The medical analogy is apt, for a cracked case is the equivalent of plugged arteries; surgery isn’t just an option, its a must. In most cases, a cracked case will ground the airplane and an overhaul will follow. No matter how much time is on the engine, splitting the case to fix a crack and reassembling it makes little sense. A full overhaul or reman is the way to go.