912iS Fuel Injected Aircraft Engine

Paper #:
  • 2012-32-0049

  • 2012-10-23
Dopona, M., Foxhall, N., and Dutzler, C., "912iS Fuel Injected Aircraft Engine," SAE Technical Paper 2012-32-0049, 2012, https://doi.org/10.4271/2012-32-0049.
The 912 engine is a well known 4-cylinder horizontally opposed 4-stroke liquid-/air-cooled aircraft engine. The 912 family has a strong track record: 40 000 engines sold / 25 000 still in operation / 5 million flight hours annually. 88% of all light aircraft OEMs use Rotax engines.The 912iS is an evolution of the Rotax 912ULS carbureted engine. The “i” stands for electronic fuel injection which has been developed according to flight standards, providing a better fuel efficiency over the current 912ULS of more than 20% and in a range of 38% to 70% compared to other competitive engines in the light sport, ultra-light aircraft and the general aviation industry.BRP engineers have incorporated several technology enhancements. The fully redundant digital Engine Control Unit (ECU) offers a computer based electronic diagnostic system which makes it easier to diagnose and service the engine.The modern fuel system consists of two fuel rails and two injectors per cylinder, pressure regulator and a return line.Redundant Sensors monitor air box vacuum, exhaust gas temperature, ambient air pressure, inlet air temperature, coolant temperature and throttle position.The injection system ensures optimal fuel and air mixture at any altitude for longer flight range and lower operating costs. This makes the engine more environmentally friendly due to lower CO2 emission levels.Other advantages for the pilots are no manual choke, no carburetor icing, and no requirement for synchronising carburetors.The three-year development period included more than 10,000 hours on the test bench and 700 test hours in the air to ensure 2,000 hours time between overhauls (TBO); the same TBO as the 912 engine.At 63,6kg (140, 2 lbs), the Rotax 912 iS engine delivers the best power-to-weight ratio in its category.
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