by Sikorsky on , reportedly due to translation issues into some foreign languages. The first production variant was the S-76A. Several improved models were produced over time. During 1982, the S-76 Mk II, equipped with more powerful engines and other refinements, was introduced. In 1987, production of the S-76B, powered by Pratt & Whitney Canada PT6B-36A and Pratt & Whitney Canada PT6B-36B engines; it was capable to attaining a maximum speed of at sea level. By early 2001, in excess of 500 S-76s had been delivered. During the early 2000s, the S-76C+ was the main version in production; it was equipped with twin Turbomeca Arriel 2S1 engines with FADEC and a Honeywell EFIS suite. This version also incorporated active noise suppression, vibration dampers and a composite main rotor. On , the S-76 C++ replaced earlier versions in production; it is powered by twin Turbomeca Arriel 2S2 engines and incorporates an improved and quieter transmission as well as minor changes in the interior equipment and avionics. By January 2006, Sikorsky had secured 92 orders for this model. Development of the follow-on S-76D was subject to four years of delays due to technical problems in expanding the flight envelope. On , the prototype conducted its first flight, and type certification was initially expected during 2011 while deliveries were forecast to start at the end of that year. The FAA issued certification on . Three prototypes were used in the certification program, with one aircraft used to certify the optional rotor electric ice-protection system. The "D" model is powered by Pratt & Whitney Canada PW210S engines driving composite rotors and incorporates active vibration control. Performance is substantially improved with the added power, but initial certification retains the same gross weight and maximum cruise speed as earlier models. The rate of manufacturing noticeably declined during the 2010s; only a dozen S-76s were delivered between 2016 and 2020. During September 2013, it was announced that the Chinese manufacturer Changhe Aircraft Industries Corporation had been contracted to produce the S-76D airframe. By 2022 April, in excess of 875 S-76s had reportedly been built. During March 2022, Sikorsky announced that it had halted new orders for the S-76 while potential overseas manufacturing partners and licensing opportunities were being evaluated. Reasons for the hold included decreasing sales volume, the high cost of supply and manufacturing, and the prohibitive costs associated with adapting the S-76 to meet increasing safety