BK 117 A - Two 450kW (600shp) Avco (Textron) Lycoming LTS 101650B1 turboshafts driving a four blade main rotor and two blade tail rotor. BK 117 B2 - Two 410kW (550shp) takeoff max continuous rated AlliedSignal LTS 101750B1s.
BK 117 A - Cruising speed 264km/h (143kt). Initial rate of climb 1970ft/min. Hovering ceiling in ground effect 13,450ft. Range with max payload 545km (295nm). BK 117 B2 - Max cruising speed 248km/h (134kt). Initial rate of climb 1900ft/min. Hovering ceiling out of ground effect 7500ft. Range with standard fuel 540km (290nm), with internal long range fuel tank 706km (381nm).
BK 117 A - Empty 1520kg (3350lb), max takeoff 2800kg (6173lb). BK 117 B2 - Empty 1745kg (3846lb), max takeoff 3350kg (7385lb), max takeoff with external payload.
Main rotor diameter 11.00m (36ft 1in), length overall 13.00m (42ft 8in) fuselage length 9.91m (32ft 6in), height rotors turning 3.85m (12ft 8in). Main rotor disc area 95.0m2 (1023sq ft).
One pilot and max seating for 10 passengers. Executive configuration seats six, standard MBB/Eurocopter configuration seats seven, standard Kawasaki version seats nine. Can be equipped for search and rescue, EMS and police work with various appropriate internal configurations.
Approx 370 BK 117s built, with 260 from Eurocopter/MBB and 110 from Kawasaki. Indonesia's IPTN licence built three BK 117s as NBK117s.
Twin engine utility helicopter
The BK 117 was developed under a joint collaborative effort between MBB of Germany (now part of Eurocopter) and Kawasaki of Japan, resulting in production lines in both countries.
The BK 117 program replaced the independently developed BO 107 and Kawasaki KH7 design studies. The BK 117 retains the former's overall configuration, with Eurocopter responsible for the helicopter's rotor system (which uses a scaled up version of the BO 105's four blade rigid main rotor), tail unit, hydraulic system and power controls, while Kawasaki has responsibility for the fuselage, transmission and undercarriage.
Development led to the BK 117's first flight on June 13 1979, the first production aircraft (built in Japan) flew December 1981, certification was awarded in December 1982, and first deliveries took place early in 1983. Initial production was of the BK 117 A1, while the BK 117 A3 with higher max takeoff weight and enlarged tail rotor with twisted blades was certificated in March 1985. The BK 117 A4 introduced from 1987 features increased performance through an increased transmission limit at takeoff power, improved tail rotor head and, on German built aircraft, increased fuel.
The BK 117 B1 (certificated in 1987) has more powerful engines and better performance, the BK 117 B2 is currently in production and has an increased max takeoff weight. The BK 117 C1 is a German development with Turboméca Arriel engines, while the BK 117 C-2 now underdevelopment features improvements from the EC 135 including new avionics.