The Cougar is a twin-engined low-wing cantilever monoplane using a honeycomb and bonded metal construction that is the hallmark of the line since the BD-1. The prototype's single spar wing was upgraded to a double-spar configuration and this allowed a wet wing.

The Cougar is powered by a pair of wing-mounted Lycoming O-320-D1D engines of 160 hp (119 kW). It carries four people at maximum cruise speed of 160 kts (296 km/h) and a typical cruise speed of 140 kts (259 km/h). It was certified under US FAR Part 23 on 22 September 1977.