The DA42 Twin Star was the first diesel-powered fixed-wing aircraft to make a non-stop crossing of the North Atlantic, in 12.5 hours, with an average fuel consumption of 21.73 litres (4.78 imp gal; 5.74 US gal) per hour (10.86 litres (2.39 imp gal; 2.87 US gal) per hour per engine).
By March 2012 the DA42 had become the major income driver at Diamond Aircraft. Company CEO Christian Dries indicated that the market focus of the company had been changed by the recession of 2008—2010 and that the company now derives two-thirds of its revenue from military and government contracts, primarily for manned and unmanned (Aeronautics Defense Dominator) surveillance aircraft.
Also in March 2012 Diamond aircraft announced they were developing a fly-by-wire version of the DA42, with the aim of reducing the accident rate in light aircraft. The system is expected to eventually include flight envelope protection, turbulence righting and autoland capabilities. The system will also include damage-tolerant by-pass capabilities, allowing flight with jammed or missing controls. The autonomous DA42 was flown and landed without ground support in 2015.
The DA 42 is a composite constructed twin-engined, low-wing cantilever monoplane with a retractable tricycle landing gear and a T-tail. The enclosed cabin has four-seats with a front-hinged canopy for access to the front seats and a top-hinged door on the left-side for access to the rear-seats.
The DA42NG “New Generation” is powered by Diamond’s 3rd Generation Austro Turbo Diesel Engine. The Lycoming IO-360 engine is also available as an option. The 125 kW (168 hp) Austro diesel replaces the Thielert Centurion 1.7 and 2.0 engines. It is known for its good fuel efficiency, it uses 12.1 litres (2.7 imp gal; 3.2 US gal) per hour while loitering at maximum endurance or 30 litres (7 imp gal; 8 US gal) per hour at maximum continuous power (92%). It is also available with optional “on top” exhaust mufflers that reduce noise levels to below 59 decibels at a height of 500 feet (150 m).
Thielert Aircraft Engines ended its production of the 1.7 litre Centurion engines (designated as TAE 125-01 Centurion 1.7) in favour of a new 2.0 litre. (TAE 125-02-99) engine. Diamond began installing this new 2.0 L. engine in early 2007. Although engine displacement increased, it was de-rated to produce the same power 101 kW (135 hp) and torque 409 N·m (302 lbf·ft) as the 1.7 L. engine.
In late 2007, Diamond aircraft announced it would begin building and installing its own aerodiesels, through a subsidiary, Austro Engine GmbH, and with other partners that included Mercedes Benz Technologies. The use of Thielert engines on the DA42 came into question due to Thielert filing for insolvency in April 2008.
Due to the insolvency of Thielert and the decisions of the insolvency administrator, including cancelling warranty support and the prorating of time-between-overhaul for the Thielert engines that power the DA42, Diamond announced in July 2008 that production of the DA42 was suspended. At the time production was suspended the DA42 was reported to have 80 percent of the piston twin market.
In March 2009 Diamond achieved EASA certification for the Austro Engine AE 300 and returned the DA42 to production as the DA42 NG. The new engine produces 20% more power, while giving better fuel economy than the Thielert engines and results in a higher gross weight and increased performance. The first Austro-powered DA42 was delivered to a customer in Sweden in April 2009, with the first US customer aircraft expected in mid-2010. The Austro-powered DA42 NG received FAA certification on 9 April 2010.