SEP vs SPA please?
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Hi Pilot DAR,
In the UK (and probably all JAA/EASA countries) SEP is "single engine piston" usually suffixed by "(L)" for landplane. So it is any aeroplane with one piston engine, there is no weight limit. There is also MEP for "multi engine piston" and a "(S)" suffix for seaplanes.
SPA is single pilot aircraft, so anything certified to be operated by one crew member, which will probably include most SEP's (AN2 or other ex-mil types?). I used this term a bit sloppily in the "checklist" thread and as you pointed out can include lots of fairly complex, high-performance stuff.