The aircraft engine I always thought needed more development was the diesel engine. It was used in the past by large aircraft and even airships but they were always considered to be big and complicated for small single or twin engined aircraft. But a company from Liechtensteincalled Thielert changed all that.
They developed an engine from the Mercedes A-class automotive power unit, which has been certified for use in aircraft by the FAA and is in use in several hundred aircraft around the world. The only problem is that Thielert have gone into liquidation. This leaves several hundred owners and companies with no support for the engine in their aircraft. Spares are becoming scarce and expensive and there is no other company authorized to do the work on them. Furthermore the gearbox and clutch between the engine and the propeller has to be inspected every 300 hours. This is a very expensive exercise, as it had to be removed and shipped to the factory for the inspection.
Cessna, with all their business experience find themselves in the same boat with 160 Thielert powered 172’s to be delivered this year and no engines to put into them. An Austrian company called Diamond are the other manufacturer who have many hundreds of aircraft powered by Thielert’s diesel engines. There are other engines being developed which will hopefully take the place of the Theilert but they are not certified yet.
Why all this sudden interest in diesel engines? Well you get a lot more bang for your buck as the specific fuel consumption is a lot better in a diesel therefore reducing fuel costs. The USAhad no motivation for diesels’ with the supply of cheap gasoline but that has all changed now. An additional advantage is there is no ignition to worry about and the engines have been developed to be a single lever control. This means the end to the prop and fuel mixture levers with the FADEC doing all the adjustments automatically.
The diesel powered single engine trainer will give the pilot more time to fly the plane instead of all the engine related monitoring tasks therefore gaining more flying skills faster and reducing the amount of time spent in the air consuming that expensive fuel. The weekend flyer will also have more time to fly the aircraft instead of being preoccupied with controlling the engine, an added safety feature.
Another advantage is the fuel it will run on. Jet A1 is going to be the fuel of choice with diesel as an alternative, this is readily available anywhere the planes fly to. Aviation Gasoline (AV Gas) is becoming a rare commodity as not all FBO’s carry it and refineries are reluctant to produce it given the small customer base. Transportation of the fuel is also a headache due to the lead content which means it normally has to be trucked everywhere to prevent lead build up in pipelines and valves. This all adds to the cost and you know whom that will be passed onto.
So the diesel engine has a lot going for it now that it can be fitted into the small aircraft and still produce the required power. I would expect to see more being the power plant of choice when the new ones are certified. It is just a pity that Thielert went the way they did and left a whole lot of people in a whole lot of mess.
UPDATE
There maybe a future for the Thielert engine after all. There are reports of several letters of interest detailing development and financing from interested parties. The insolvency administrator will evaluate the offers and reduce them to a few which will be given due diligence and a decision will be made for the engine production to be taken over.
December 2008
Diamond has come up with a plan for the owners due to new developments. More infomation at www.thenog.org
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