MBB/Kawasaki BK 117

https://en.wikipedia.org/wiki/MBB/Kawasaki_BK_117

The MBB/Kawasaki BK 117 is a twin-engined medium utility–transport helicopter.
It was jointly developed and manufactured by Messerschmitt-Bölkow-Blohm (MBB) of
Germany and Kawasaki of Japan. MBB was later purchased by Daimler-Benz and
eventually became a part of Eurocopter, which was later rebranded as Airbus
Helicopters.

On 25 February 1977, MBB and Kawasaki signed a cooperative agreement to abandon
their independent efforts to design twin-engined general purpose helicopters in
favour of a collaborative venture to development of a new rotorcraft for that
role. While the programme's costs were shared equally, the workshare was divided
into certain areas of the design. MBB utilised their expertise with the rigid
rotor system used on the earlier Bo 105 to develop the majority of the dynamic
systems and flight controls, while Kawasaki focused on the airframe, structural
elements, and various other components. On 13 June 1979, MBB's flying prototype
conducted its maiden flight at Ottobrunn, Bavaria, Germany; months later, it was
followed by the Kawasaki prototype at Gifu, Chubu region, Japan on 10 August
1979.

Each company established their own final assembly line, producing the BK 117 for
their respective regions. The BK 117 has proven to be popular for passenger
services and VIP-transport, the cabin can be outfitted with various seating
configurations, seating between seven and ten passengers. It is also used for a
diverse range of operations, such as aerial crane and sling work, law
enforcement, and military transport, and is exceptional as an air ambulance and
search and rescue platform. During the 1990s, due to its popularity, a refined
derivative, initially marketed as the BK 117 C-2 before being rebranded as the
EC 145 and later as the H145, was developed from the BK 117 C-1 version; this
improved version of the rotorcraft has since succeeded the original BK 117 in
production.

Design

The MBB/Kawasaki BK 117 is a twin-engined medium utility–transport helicopter.
It possessed several attributes that lend itself to performing many different
roles, such as twin-engine redundancy, sizable clamshell-shaped rear-facing
double doors, and a relatively spacious cabin; one mission to which it was
deemed to be particularly suitable was the emergency medical services (EMS). The
airframe is composed of rivetted metal, making minimal use of composite
materials, and machined to a high standard; in order to free up internal space,
both the engines and transmission are positioned above the main cabin.
Considerable efforts were made to reduce the weight of the aircraft were
possible albeit without compromising the aircraft's structural integrity. The
cabin could be outfitted with various interiors in order to suit its purpose, or
to incorporate greater comfort levels, which included measures to dampen both
noise and vibration.

Early versions of the BK 117 is powered by a pair of Lycoming LTS101 turboshaft
engines, rated to generate 550 shp at takeoff with considerable reserve power to
guard against a single engine failure. While each engine possesses sufficient
power to maintain flight and even takeoff in the event of a single engine being
rendered inoperable, the type also has favourable autorotation capabilities. In
order to extend their operational lifespan and increase their reliability, MBB
tuned the engines to operate at lower-than-standard revolutions per minute
(RPM). The engines are regulated using a specialised control system which
smoothly and evenly regulate RPM and torque between both engines, even during
vigorous manoeuvers. Power management has been greatly eased via the addition of
an automatic engine-governor system, allowing pilots to simply monitor the
torque and engine temperature gauges. The aircraft can be suitably equipped for
flight under instrument flight rules (IFR) as well as for single-pilot
operations.

Role
Utility/transport

National origin
Germany/Japan

Manufacturer
Messerschmitt-Bölkow-Blohm (MBB)/Kawasaki Heavy Industries

First flight
13 June 1979

Introduction
9 December 1982

Status
in production, in active service

Primary users
DRF
ADAC

Produced
1979–present

Number built
443

Developed from
MBB Bo 105

Developed into
Eurocopter EC145

Operational history (see "Operators")

A single BK 117 A-3 (c/n 7106) was leased by the Canadian Forces Air Command for
a test program and designated as the CH-143. When the program was over, the
aircraft was returned to MBB Canada.

A BK117 helicopter contracted by the New South Wales Rural Fire Service to fight
fires crashed on 17 August 2018, the pilot died in the crash.

Specifications (BK 117 B-2)

General characteristics
Crew: 1
Capacity: up to 10 passengers
Length: 9.91 m (32 ft 6 in) (fuselage length)
Height: 3.85 m (12 ft 8 in) (rotors turning)
Empty weight: 1,727 kg (3,807 lb)
Max takeoff weight: 3,350 kg (7,385 lb)
Fuel capacity: 697 L (183 US Gallons, 153 Imp Gallons) internal fuel
Powerplant: 2 × Textron Lycoming LTS 101-750B-1 turboshaft, 442 kW (593 hp) each
Main rotor diameter: 11.00 m (36 ft 1 in)
Main rotor area: 95.03 m2 (1,022.9 sq ft)

Performance
Maximum speed: 250 km/h (160 mph, 130 kn) at sea level
Never exceed speed: 278 km/h (173 mph, 150 kn)
Range: 541 km (336 mi, 292 nmi)
Service ceiling: 4,575 m (15,010 ft) (max certified altitude)
Hover Ceiling: 3,565 m (11,700 ft) (in ground effect)
Rate of climb: 11.00 m/s (2,165 ft/min)




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