Rotax 503

503
Rotax 503 trade show display
Type Piston aero-engine
National origin Austria
Manufacturer Rotax
Major applications Quad City Challenger
Blue Yonder EZ Flyer
Produced until 2011
A Rotax 503 mounted on a Flightstar II ultralight
The prototype Blue Yonder Twin Engine EZ Flyer is powered by two 503s in pusher configuration
Air Creation Racer ultralight trike with Rotax 503 mounted up-right. Below the muffler is the smaller after-muffler.

The Rotax 503 is a 37 kW (50 hp), inline 2-cylinder, two-stroke aircraft engine, built by BRP-Rotax GmbH & Co. KG of Austria for use in ultralight aircraft.[1][2]

For decades the engine was one of the most popular and reputedly reliable aircraft engines in its class (two-stroke, under 60 horsepower),[3] and it remains widely used and supported.[4]

As of 2011 the Rotax 503 is no longer in production.[3][5] However, a Russian manufacturer has developed an approximate reproduction, the RMZ 500.[3] Rotax subsequently offered only one other two-stroke engine for aircraft, the partially water-cooled Rotax 582.[4]

  1. ^ BRP-Rotax GmbH & Co. KG (2006). "OPERATORS MANUAL FOR ENGINE TYPES 447, 503 & 582" (PDF). Retrieved 9 March 2009.
  2. ^ Raisner, William: LEAF catalog, pp. 6-105. Leading Edge Airfoils, 1995.
  3. ^ a b c Johnson, Dan: "What’s Affordable in 2022? A New “503,” Wheeled-Carriages, and Two-Place PPGs," February 3, 2022, ByDanJohnson.com, retrieved June 29, 2023
  4. ^ a b Prizio, Dave: "Firewall Forward: Rotax service Training," July 19, 2013, Kitplanes, retrieved July 5, 2023
  5. ^ "Rotax Website - Aircraft Overview". Brp-powertrain.com. Retrieved 1 September 2012.