Superior Air Parts XP-400

The Superior Air Parts XP-400 is an aircraft engine, designed and produced by Superior Air Parts of Coppell, Texas, United States for use in homebuilt aircraft.

The company is owned by the Chinese company Superior Aviation Beijing, which is 60% owned by Chairman Cheng Shenzong and 40% owned by Beijing E-Town, an economic development agency of the municipal government of Beijing.

Design and development
The engine is a four-cylinder four-stroke, horizontally-opposed, 400 cuin displacement, fuel injected air-cooled, direct-drive, gasoline engine design. It produces 215 hp, with an 8.9:1 compression ratio.

The engine is not type certified and is therefore intended for homebuilt aircraft.

In March 2019 the engine type was withdrawn from service and all customer engines were subject to a mandatory, immediate buy-back by the manufacturer to remove them from service. The company made this decision based on detonation problems found in some XP-400 engines that could not be resolved. Due to parts commonality, the decision was made to buy-back the Superior Air Parts XP-382 engines as well.

In February 2020, Superior settled a lawsuit regarding the 2016 fatal crash of a Van's Aircraft RV-8A for US$5M. The crash was due to the failure of the crankshaft in the installed XP-400 engine. In the accident investigation the NTSB determined that the crankshaft failed due to metal fatigue. The crankshaft had 20 hours of flight time on it at the time of failure.