The R66 received both type and production certificates from the U.S. Federal Aviation Administration (FAA) on October 25, 2010.

[18] On 25 January 2017 Robinson announced that it had delivered its 12,000th aircraft, an R66 to a charter and tour operator, Fly Karoo Air Services.

[19] On 17 July 2017, Robinson introduced the TB17 lithium-ion phosphate battery as optional equipment.

[2] The R66 is a single-engined helicopter with two-bladed main and tail rotors, and a fixed skid landing gear.

The R66 is constructed from advanced composites, aluminum alloy (sheet), and chromoly steel.

[23] The RR300 has a simplified single-stage centrifugal compressor which makes it less expensive and is expected to result in lower maintenance costs.

Robinson redesigned the tail in the 2020s to utilize a symmetrical horizontal stabilizer to hopefully reduce the danger of mast bumping accidents, such as during low-G conditions maneuvers.

This type of maneuver is more dangerous in a two bladed helicopter, and is warned against, however, rare but tragic accidents have led to further investigation and improvements, due to the typically catastrophic nature of such incidents.

[26] The FAA approved the new empennage, which should improve roll stability when the helicopter is in flight at high speed.

Because of the size and weight of the R66 and the height of the tail from the ground, as compared to the R22, it is extremely difficult if not impossible for a single person to move the helicopter this way.

All models and years of the R66 include a ¾” diameter tow ball mounted on the bottom of the fuselage, near the front and offset slightly to the left.

This makes it possible for a single person to move the helicopter, even over significant distances or not-level surfaces.

Tow carts are available with no motive power, a gas engine or one or two electric motors operated from one or two batteries.