The CH 640 was developed from the two-seat type certified AMD Alarus, also called the Zenair CH 2000, by increasing the span of the wings and stabilator, to accommodate the larger engine and increase in gross weight. The design was also influenced by the Zenith CH 601 and the Zenair CH 300. The design goals were to produce a simple four-seat aircraft capable of flying cross country flights with full seats.
The CH 640 is a four-seat, low-wing touring aircraft with tricycle landing gear and a single engine in tractor configuration. It has a standard empty weight of 11470NaN0, a gross weight of 22000NaN0 and an acceptable engine power range of 150to. The recommended engine is the Lycoming O-360 of 1800NaN0.
The aircraft is made from 6061-T6 aluminum. Its 31.51NaN1 span wing is a cantilever structure and is equipped with flaps. The 461NaN1 wide cabin is accessed via two gull-winged doors. The construction time from the factory-supplied standard kit is estimated at 1250 hours to complete and the quick-build kit at 750 hours. In 2011 the kit cost US$28,995, while finishing a completed aircraft was estimated to cost between US$45,000 to $99,000, depending on options, engine and avionics installed. In December 2011 there were 50 completed and flying.
In evaluating the CH 640 AeroNews Network said, "It's a tremendously stable little airplane and a fair amount faster than what you might think."