Introduced in 2010, BK117-850D2 is a twin-engined medium utility–transport helicopter.The 850D2 variant is an STC (Supplementary Type Certificate) development (i.e., re-engined) of BK117 B-2 incorporating Honeywell LTS 101-850B-2 engines aimed at improving OEI and Category A performance.Development and certification was conducted in New Zealand by Airwork of Ardmore, NZ, in conjunction with Flight Structures Ltd.