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News of March 23, 2008
Considering the Cessna 172 Thielert after the Flying Magazine report (April 08 issue.)
Well, Cessna now sells a diesel airplane. And it is the famous, eternal 172, the most ubiquitous flying machine in history, a machine which will certainly still be flying in huge quantities 50 years from now. And Flying Magazine has published a very comprehensive report on the product. A major event, considering that only 7 years ago, when I first published the DieselAir Newsletter, the prevailing opinion was that the aero diesel engine would never get to the US market. And the report is very favorable, while underlining objectively all the pros and cons of this product. Bravo to Roger Goyer who wrote the report.
The pros: The 172 Thielert, called 172TD, is fast: 130 knots at 10,000 feet, despite a take-off power of only 155 HP versus 180 for the SP model (180 HP). This is of course because it is a turbo with a constant speed prop, and can fly higher. It is fuel efficient as one could expect: At 130 kts and 10,000 ft it burns 7.8 gallons per hour; but at 5,000 ft and 112 knots, only 5.8 gph. The test did not cover fuel flow at best glide speed, a test which would have verified our most important point: Between and a bit above best glide speed (1.3 to 1.5 times stalling speed), it is so low that one can consider staying in the air for ever, addressing any realistic need or factor preventing any landing anywhere such as unexpected fog, or obligation to fly back because of icing. (Yes, of course, it would never happen to you because you are such an experienced pilot. But have you ever thought that if GA is going to grow again, there will be again lots of inexperienced pilots flying?) I hope someone will complete that test some day. All these combined confirm our other point: A 172 diesel is a practical IFR machine, something which is somewhat questionable for a gasoline 172 because of its limited fuel capacity and relatively short range with full IFR reserves.
However, the no-wind range at 85% power (118 kts at 8,000 ft) is 588 NM. A respectable figure for sure, but relatively modest for a diesel. How come? This is because Cessna decided to reduce fuel capacity to 44 gallons instead of 50 on a 172SP. A 6 gallons difference with a fuel flow of 5.8 gph can be important. Why did Cessna do that? To understand them, we must discuss what the accessible market for this product is during the next ten years.
In the US, interest for diesel airplanes is slowly growing, but not that fast. Avgas is still very accessible except perhaps in Alaska. It is still priced much lower than anywhere else. Engine prices from Lycoming and Continental for new or remanufactured engines are low because these engines are still produced in mass quantities with fully amortized tooling at costs in a very low dollar. In front of them, Thielert, and even more SMA or Wilksch diesels, are produced in tiny quantities at costs in sky-high Euros or Pounds. It will take several years – at least 5, more probably 10 years - before their manufacturers can organize to outsource at lower cost and produce in such quantities. Thielert is the leader, but it manufactures in costly Germany the most complex of all aero diesels: liquid cooled, gear transmission with clutch and flywheel. It reflects in engine prices. (Besides, have you ever noticed that a BMW is more pricy than a Ford?) In the US, a private pilot considering buying his first new plane will think twice before buying a 172TD which, incidentally, is priced at $300,000 which is 15,000 more than a 172SP and some 50,000 less than a 182. If he is going to fly 150 hours a year, his choice is not obvious.
But this is completely different for a US flight academy planning to fly its 172s at 1,000 hours per year. In this case, Cessna demonstrates that the operating cost, even including very high TBO costs for the Thielert, will be $5 per hour less than with the Avgas model. That means $5,000 per year. And this difference will grow together with the price differential between Avgas and JetA, which can only go up. However, note that a flight academy does not need long range planes… Therefore the 44 gallons, allowing a higher payload.
It is also completely different, and more so, for foreign flight academies who have to pay a much higher fuel price differential, and who face the growing problem of vanishing Avgas.
And then you have the countries where Avgas has disappeared, or is available only in reusable tanks of dubious cleanliness, notably Africa. And the countries who never had Avgas at all, such as China. Overseas, diesel airplanes are in demand right now. The very small but growing US production of refurbished Cessna 182s re-engined with the SMA 230HP diesel is mostly for export. When the Maule MX9 diesel will finally obtain its long waited STC, it will first sell overseas. The overseas market needs diesels, period. Whether they can fly non-stop at 200 kts for 1,000 NM with 2 hours reserves will be nice, but they can wait. It will be the overseas market which will pull aero diesel production figures up to where costs will eventually go down.
In the mean time, Flying Magazine underlines the cons: Right now, a Thielert engine is very expensive. Also its TBO. It needs preventive maintenance at key times such as 300 hours, and a major inspection at 1,200 hours. No doubt this will improve with time. Also other diesels will compete with Thielert proposing simpler designs: Air-cooled non geared, O-engines such as the SMA, and 2-strokes engines such as the Wilksch, the Gemini and the DeltaHawk. And do keep in mind that, in the world of aviation, the only things that go fast is the airplane itself when it does fly, which is not very often. All the rest moves much, much slower than in any other industry…
Meanwhile, Paul Bertorelli (Aviation Consumer) is quite right to question if diesel are more economical. Right now, in the US, they are not, unless you fly 1,000 hours per year. Overseas, they are coming, period. And GA growth is happening overseas. So, the diesel will come. And when it will, finally, come full swing in the US, yes, by then, with Avgas at maybe 10 dollars a gallon, it will be economical. And in the mean time, Cessna is here now, and will be here by then. Bravo to Cessna: there still are US manufacturers who understand corporate strategy.
posted at 6:56 PM
News of March 16, 2008
FAA issues emergency AD for Thielert Engines
In-flight engine shutdowns have led the FAA to issue an emergency airworthiness directive (AD)[http://download.aopa.org/epilot/2008/20080652ad.pdf] for model TAE 125-02-99 engines from Thielert. The shutdowns were the result of cracks in the high-pressure fuel lines caused by excessive vibration. The March 12 AD affects engines with serial numbers from 02-02-1500 through 02-02-2279. The engines are installed on Cessna 172, Diamond DA42, and other aircraft. Before the next flight, owners must install a new high-pressure fuel line and bracket. Special flight permits are allowed for a single VFR flight of up to two hours to the nearest maintenance station.
posted at 4:27 AM
News of March 08, 2008
News from the Ecofly diesel light aircraft (Germany)
Ecofly, the manufacturer of the Smart aircraft engine conversion, has started flight testing program of the new 80 hp Smart-Roadster engine. This engine was designed by Mercedes Benz and is used in the new Smart Roadster car. It is an upgraded M160 powerplant of the Smart citycar.
Mercedes-Benz designed this
0.7 liter, 3 cylinder turbo motor to be light (132 pounds in car trim), compact, quiet and very efficient. The all aluminum engine has dual ignition and an intelligent turbo charging system that develops rated horsepower to over 8,000 feet and "overboosts" to develop additional power at low rpm. Cruise speed at a mild 4300 rpm is 111 mph burning less than 2.6 gallons/hour. Bosch fuel injection system eliminates carburetor icing and gives the engine great fuel efficiency. The Ecofly conversion of the engine incorporates a toothed belt reduction drive of 2.1 to 1 and includes a centrifugal clutch that engages the propeller at 1300 rpm. The package is very quiet, was rating only 54 dba during JAR certification testing. The installed weight is 11 pounds more then that of the 912s. See http://www.ecofly.de/english.htm
posted at 3:51 AM
What is the future of Avgas?
The following was published on the Blog of Canadian Owners and Pilots Association (COPA) Flight 8 Ottawa, Ontario, Canada: This has been an interesting question for a number of years, but most people have not been paying attention. The heat was recently cranked up a notch by comments made by the new President of Teledyne Continental Motors, Rhett Ross. In an interview with AvWeb Ross stated that he thought it would only be a matter of time before aviation was ‘forced out’ of using 100LL. His company is proceeding full speed in the development of a 300 hp diesel engine that will be the first of a series of jet-fuel burning diesels from 100-300 hp. You can tell by the fact that they hope to have this new engine certified by late 2009 or early 2010 that Continental considers this a priority issue.
But is there a threat of 100LL disappearing in that sort of short term window? The answer is an emphatic ‘yes’ and GA needs to be ready for it. We used to have four grades of Avgas - 80/87, 91/96, 100/130 and 115/145. The refining industry just stopped making each one of those over time and it caused some real heartache, especially for owners of aircraft that needed 115/145, because they could not go to a higher grade. A lot of engines stopped flying and some aircraft left service or got re-engined to turbines. A few years ago there was a specification developed for 82UL (for unleaded), but no refiner has shown any interest in making any of it. Too small a market to bother.
What might cause 100LL to go away? There are currently two different types of threats to the one remaining grade of avgas. The first is economic and the second is environmental. From a refiner s economic perspective 100LL is hard to justify making at all. The market for it is tiny and spread out far and wide. The specifications for it are very tight which makes it expensive to produce. It also needs special handling at the refinery and during transport, because it contains tetra-ethyl lead (TEL) - it cannot come into contact with other fuels. It requires dedicated everything as a result. Overall making 100LL is a pain for the refiners and they wish they did not have to do it. There are only two refineries in North America that make 100LL. There is also only one company in the whole world that makes the TEL that is an essential ingredient: Innospec of the UK. If they decide to stop making this very toxic substance, 100LL cannot be made anymore. On any given day the world has about a 30 day supply of 100LL on hand. Gone are the days of vast quantities of gas being stored - it is all ‘just in time’ delivery these days.
These economic factors make the existence of 100LL very precarious - today, not just years from now. Everyone knows that leaded auto fuel was phased out in the early 1980s because lead in gasoline is a toxic substance. No matter what the combustion process or temperature the tailpipe products of lead combustion are toxic to humans and most likely cancer-causing as well. In the USA, the Environmental Protection Agency is once again looking at 100LL and why it is the last leaded fuel in use. Many environmental groups want it removed as well and not without good reason. As Rhett Ross pointed out this week, this will happen at some point, either from the economic or environmental perspective. The question for pilots and aircraft owners is ‘what then?’
Auto fuel will still be available for some time, so if your aircraft is designed to run on auto fuel or can use it through an STC, you will be using that. I would bet that those empty 100LL tanks at the airport will start to be filled with premium autofuel, rather than sit empty. What if you cannot run on autofuel? Lots of aircraft cannot, like 2007's best-selling new aircraft, the Cirrus SR22, for just one example. The new Cessna 350 and 400 can't either. Companies like Continental will be very happy to sell you a jet-fuelled retrofit diesel engine a few years down the road. Hopefully you will not need one before they have them available. Many aircraft types will eventually have diesels available under STC. The folks at SMA diesels already have some STCs for their one product, the 230hp SR305 engine. It has been available for the Cessna 182 for a few years. There have been few takers, because of the cost. If the cost of the SMA conversion is any indication then be prepared to pay around $100K for the conversion to jet fuel. The added bonus will be lower fuel consumption and longer range as a result. Of course for many older aircraft this cost will be several times more than the aircraft is worth. Also the removed gasoline engine will not fetch much when there is no fuel for it - perhaps scrap value.
I do not think used avgas-only powered aircraft are going to fetch high prices at that point. So what can the lowly aircraft owner do in light of Ross comments? Probably make like Boy Scouts and ‘be prepared’. You now know what is going to happen when the 100LL taps run dry, so make a plan. Will you run on autofuel? Will you retrofit a jet-fuel burning diesel. Will you transition to rubber band power? Just do not be surprised on the day when Ross prediction happens and general aviation is ‘forced out’ of 100LL. (Signed Adam Hunt, 2/18/08)
DieselAir Comment: The Cessna 182SMA has obtained his STC only since January 07, and does find takers since over 50 are flying now. And many, many more Diamonds and Cessna 172s with Thielert engines are flying in Europe and overseas. We also expect market value of diesel aircraft to improve precisely as Avgas price and availability becomes more of a problem. However we think that Adam Hunt is somewhat pessimistic for the US: Avgas consumption (FAA Statistics) was still 300 million gallons in 2000, is now some 240 million gallons, and is expected to go slowly down to 230 million in 2020. What we can expect is Avgas prices to gradually increase and the price differential with JetA as well.
posted at 3:33 AM
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