MBB/Kawasaki BK 117

Updated: October 2026 – If you saw a rescue helicopter land on the Autobahn in the 1980s or 1990s, there was a good chance you were looking at a BK 117. The twin-engine helicopter, a German-Japanese joint effort, was the workhorse of many air rescue and police units back then. Today the classic BK 117 has become rare, but its genes live on in one of Europe’s most common helicopters: the Airbus H145. Here you learn how the BK 117 came about, which versions exist and how to tell it from its successors.

What is the BK 117?

The BK 117 is a light-to-medium twin-engine helicopter for up to ten passengers. It was developed as a multi-purpose helicopter: passenger transport, VIP flights, sling-load work, police missions, search and rescue and above all air rescue. For the latter it brings ideal prerequisites, because the high-mounted tail boom leaves room for big clamshell doors at the rear, through which a stretcher can be slid directly into the cabin.

The name reveals its origin. B stands for Bölkow – meaning the German aerospace group Messerschmitt-Bölkow-Blohm (MBB) –, K for Kawasaki Heavy Industries of Japan. In the late 1970s, both companies had their own plans for a larger twin-engine helicopter and combined them. You can learn more about the German partner on the page for the MBB Bo 105, the smaller sibling that supplied important components for the BK 117.

History: a German-Japanese joint project

On February 25, 1977, MBB and Kawasaki signed the agreement for joint development. The two partners split the development costs equally, and in 1977 the German federal government additionally pledged financial support. The division of labor was clearly set: MBB contributed, among other things, the rotor system, the tail boom, the controls and the hydraulics. Kawasaki was responsible for the airframe, main gearbox, landing gear and electrics.

The MBB prototype took off for its first flight on June 13, 1979, in Ottobrunn near Munich, and the Japanese prototype followed on August 10, 1979, in Gifu. After three and a half years of testing, the German Federal Aviation Office (Luftfahrt-Bundesamt) granted certification for the first production version, the BK 117 A-1, on December 9, 1982. Japan followed a few days later, and the US authority FAA in March 1983.

Production ran in parallel in both countries: in Germany mainly in Donauwörth, in Japan at Kawasaki. In addition there was a small license production in Indonesia under the name NBK-117, which however never got beyond a few units. Figures for the total number of classic versions vary depending on the source, but they are in the range of several hundred aircraft.

In terms of company history, the BK 117 passed through several hands. MBB was absorbed into Daimler-Benz Aerospace (DASA), whose helicopter division formed the manufacturer Eurocopter together with Aérospatiale. Eurocopter eventually became Airbus Helicopters, now part of the Airbus group. That is why you find the BK 117 under the manufacturer Airbus in Planetrack.

Technology: Bo 105 genes in a bigger fuselage

Technically, the BK 117 builds on proven ideas. The four-blade, hingeless main rotor goes back to the Bo 105 principle and makes the helicopter very agile. The two turbines and the main gearbox sit above the cabin, leaving a large, freely usable space inside.

The airframe consists mostly of riveted metal, with composite materials still playing a small role. Typical is the high-set tail boom with the tail rotor also mounted high up. That has a practical side effect: anyone working on the ground behind the helicopter, for example when loading or unloading a stretcher, is better protected from the spinning tail rotor.

Version	Engines	Certification (Germany)	Notes
A-1	2 × Lycoming LTS 101-650B-1	December 1982	first production version
A-3	2 × LTS 101-650B-1	March 1985	larger tail rotor, higher takeoff weight
A-4	2 × LTS 101-650B-1	July 1986	improved gearbox and tail rotor head
B-1	2 × LTS 101-750B-1	December 1987	more powerful turbines, more payload
B-2	2 × LTS 101-750B-1	January 1992	3,350 kg takeoff weight, better performance in heat and at altitude
C-1	2 × Turbomeca Arriel 1E/1E2	October 1992	switch to French engines, improved tail rotor

The B-2 is the best-known version of the Lycoming generation. With a maximum takeoff weight of 3,350 kilograms, a main rotor eleven meters in diameter and a range of just over 500 kilometers, it was a versatile working tool for its time. With the C-1, the program switched to Arriel engines from Turbomeca (now Safran) – a decision that still stands in today’s H145.

Interesting for tech fans: in New Zealand, the maintenance company Airwork developed a conversion around 2010 that gives B-2 aircraft more powerful LTS-101-850 turbines (BK 117-850D2). Around 50 helicopters were modernized this way by the mid-2010s – one reason why classic BK 117s are still in service mainly in New Zealand and Australia.

From the BK 117 to the H145: the family tree

For spotters, the BK 117 is interesting above all because it is the ancestor of an entire family. All successors share a common type certificate with it – technically speaking, even the newest five-blade H145 is still a BK 117.

The family has also made a career in the military: the US Army flies an EC145 variant as the UH-72 Lakota, and the Bundeswehr (German armed forces) is receiving the current generation as the H145M. Details are on the H145 page.

How to recognize the BK 117

Identification lives on comparison. Three observations help you separate the classic BK 117 from its relatives.

As always, the registration has the last word. The exact version, including year of manufacture, can be looked up in the aviation authorities’ registers – how that works is shown in the article Understanding aircraft registrations. German civil helicopters carry registrations beginning with D-H; the system is explained in the article on German registrations and weight classes.

General strategies for sorting helicopters by rotor, tail and fuselage shape are in the guide How to recognize helicopter types.

In service: the air rescue classic

The BK 117 earned its reputation mainly in air rescue. Two turbines meant more safety on missions over cities and at night, the roomy cabin offered space for the patient, emergency physician and equipment, and the rear doors made loading easier.

Germany: ADAC Luftrettung added the BK 117 to its fleet as early as the 1980s, and DRF Luftrettung also operated a large BK 117 fleet for many years. Both organizations have since replaced the classic aircraft with more modern types such as the H135 and H145. The BK 117 also saw police use: the North Rhine-Westphalia police received its first aircraft in 1990, and until 2017 four BK 117s formed the core of its flying squadron.

International: The BK 117 spread far beyond Europe. In Japan it flies with prefectural police forces, among others, and in Australia and New Zealand with fire, police and rescue services. Greece’s fire service uses BK 117 C-1s, in Spain and Chile police units flew or fly the type, and in South Africa the air force used it. The BK 117 is also well known in air rescue in the USA.

Location	Chance of success	Why
German air rescue bases	very low	ADAC and DRF now fly H135s and H145s
Aviation museums	high	The prototype P2 stands in Bückeburg
Smaller charter and aerial work operators	low to medium	Used BK 117s remain in service
Japan, Australia, New Zealand	medium	Numerous classic aircraft still fly there

Flight tracker services often reveal whether an aircraft is airborne right now – the designator BK17 helps with filtering. How to find rescue and police helicopters specifically is explained in the article Tracking helicopters on a flight tracker.

Spotting tips for a rare classic

Because the BK 117 hardly flies in everyday service in German-speaking countries anymore, it pays to take a deliberate look at every helicopter with an open tail rotor and rear doors. A few tips for the hunt:

Photo technique: As with all helicopters, shutter speed decides. Too short an exposure freezes the rotor and makes the aircraft look lifeless. So expose a little longer and pan smoothly. How to feel your way to the right values is shown in the guide Photographing propellers: the right shutter speed. For profile shots that show off the rear doors and tail boom, the side view is ideal.

Consideration on missions: If a BK 117 still flies in rescue or police service, the same rules apply as with any emergency helicopter: keep access routes clear, keep your distance from the landing site, and don’t photograph patients or accident scenes. What you generally need to keep in mind when photographing aircraft is summarized in the article Is plane spotting legal?. The article Helicopter spotting collects general tips for rotorcraft.

Common mix-ups and how to rule them out

Once you have a BK 117 in the can, it is a nice example of a sighting with rarity value. How to rate such finds is described in the article Spotting rare aircraft.

Conclusion

The BK 117 is a piece of German-Japanese aviation history and at the same time the starting point of a helicopter family that now operates all over Europe. An open tail rotor, a high tail boom with rear doors and a compact cabin give away the classic; the type code BK17 and the registration provide confirmation. In everyday life you rarely encounter it in Germany anymore – all the more reason to enjoy the hangar entry when it does work out.