Andrzej Jeziorski/SEOUL

Socata has begun construction of the first prototype of what will eventually become a range of diesel-engined aircraft. The French manufacturer hopes to fly its MS250 Morane light single at next year's Paris air show in June.

The prototype of the four/five-seat Morane will have a conventional Textron Lycoming IO-540 piston engine, however, while trials continue on the new powerplant. The company has been flight testing a prototype of the new Morane Renault diesel engine since March on a modified TB20 Trinidad at Tarbes, near Toulouse.

The four-cylinder, 187kW (250hp) Morane Renault MR250 piston engine runs on jet A1 fuel, which is sold at about one-third of the price of avgas. The 5 litre aluminium engine has been developed by the Société de Motorisations Aéronautiques, a joint venture between Socata and Renault, and the powerplant should eventually become available to other general aviation manufacturers.

Diesel aircraft engines have been something of a Holy Grail for general aviation manufacturers in the past, with companies such as Zoche and Wankel in Germany arousing much interest with their projects, but never progressing beyond bench tests. The technology offers huge potential savings in direct operating costs (DOCs).

Socata claims that its powerplant offers a cut in DOCs of 35%, compared with the similar, conventionally powered TB20. The MS250 is derived from the TB20 airframe, with the addition of winglets, more cabin headroom and other minor aerodynamic refinements. It will be closely followed on to the market by the MS180 Morane, with fixed undercarriage and a 134kW MR180 engine.

According to Socata, the only difference between the two engines is in the power of the turbocharger and the revolutions per minute. The MR250 engine is about 10-15% lighter than the similarly powerful IO-540 which powers the TB20.

In 1999, Socata plans to fly the first prototype MS300 Epsilon Mk2 primary and basic military trainer, with a 223kW MR300 piston engine. The aircraft will be a diesel derivative of the Lycoming AEIO-540-powered TB30 Epsilon, now in service with the French air force for ab initio training, and will be available for delivery "24 months after the first order".

The manufacturer claims that it will be able to offer performance comparable to that of the $2 million Pilatus PC-7, but at a target price of $1 million. Socata says it already has 60 options on the MS250, primarily from European flying schools, while the MS300 has generated "a lot of interest in Asia" from unnamed air forces.

Meanwhile, according to Socata, the Asian economic crisis has cost it some $50 million in lost sales in the past 18 months. Key casualties include a follow-on order for 16 TB10s, three TBM700 turboprops, as well as training and simulation equipment, from the Indonesian communications ministry's ETA Curug flying school.

The manufacturer, however, has managed to sell six TB20s to the Indira Gandhi Flying School in India, in a deal signed on 12 October. Socata says it does not expect sales in Asia to pick up for another two years - or five in Indonesia, which has been particularly badly hit by the crisis.

Source: Flight International