The Sikorsky S-72 Rotor Systems Research Aircraft (RSRA) was funded by NASA and the US Army to test advanced helicopter rotors in flight and featured detachable wings. Two S-72s were built and first flown in Stratford, CT on Oct 12, 1976. The first aircraft was delivered in July 1977 to NASA Wallops Island Flight Test Facility, VA and made its first full compound flighton April 10, 1978. The second S-72 was delivered to the NASA Ames Research Center in Fall 1978 and late joined by aircraft No. 1 in Sep 1979. Later used for RSRA/X-wing program 1986-1987. Msn 72-002 was NASA 546, 741 and N741NA.

Del 21 Mar 1980 Test Registration as N58201 Former Trans World Airlines (TWA) as N58201, Dubai Air Wing as A6-SMR, Interface Operations as N992MS, VP-BLK

Del/ 18 Mar 2014 Test Registration as N662GA

Del 29 Sep 1997 Test Registration as N521GA

This 2008 built airframe is owned by Air Methods. It's first HEMS assignement was in California (registered N276AM), followed by a brief contract for the University of Wisconsin Hospital in 2018/19 (registered N911UW), before being re-located to Riverside in California once again in September of 2019, becoming N738AM.

Established in 1993, Ashland, OR based Brim Aviation favors MD Helicopters NOTAR machines for utility work. Two MD600Ns, an MD902N (and as needed, a leased MD520N) out number the AW109S and Bell 204 that make up the rest of their fleet. N60BK was registered to the company in 2008. It carries a very small company logo on the forward fuselage.

Del 30 May 2019 Test Registration as N1020L

Del 14 February 2007 Test Registration as C-FLLO, Former Bombardier Aerospace Corporation as N71ZZ,Bombardier Aerospace Corporation, GEX Leasing Corporation as N421SZ,GEX Leasing Corporation, Global Flight as N928SZ

The highly modified DHC-5 Buffalo Quiet Short-Haul Research Aircraft (QSRA) was photographed stored on the NASA Ames Research Center ramp at Moffett Federal Airport in Mountain View, California in February 2020. It was also known as the Quiet STOL Research Aircraft.