South African has had a long and happy relationship with the Airbus H145 series and its pre-genitors. In its MBB BK-117 form the helicopter was the mainstay of SA Police operations in the urban centres, where two engine safety was considered essential. Since then the type has undergone many improvements, to get to the current Airbus H145.

The subject of this evaluation is ZT-HOP, the first H145 to be delivered to South Africa. It is owned by Aerios Global Aviation (AGA) the well-respected offshore helicopter operator based in Cape Town, who acquired it for ship support by AGA subsidiary Heli-Launch OPLSA.

DEVELOPMENT

Despite its US10m plus price tag, the H145 is Airbus’s best-selling helicopter., notching up 186 sales in 2023. So the design is clearly one that has stood the test of time.

The H145 began life in 1979 as a joint development between Messerschmitt-Bölkow-Blohm (MBB) and Kawasaki. Called the MBB-BK 117, it was developed from the MBB Bo 105.

This helicopter pioneered the use of a revolutionary hinge-less fibreglass main rotor developed by German engineer Ludwig Bölkow. Having established a reputation for reliability and safety, during the early 1970s, MBB, along with major shareholder, Boeing Vertol, began studying options for producing an enlarged derivative of the type to grow out from the Bo 105 base.

However, Boeing withdrew from the project and so MBB partnered with Kawasaki for the development of the BK-117. MBB was then acquired by Daimler-Benz and eventually became a part of Eurocopter, which in 2015, became Airbus Helicopters. With the change of ownership and branding, the helicopter’s designation changed from MBB-BK117, to EC117, and now to H145, which, in recognition of its original type certificate, is certified as a BK117 D3.

MBB provided their expertise with the rigid rotor system they had gained from the earlier Bo 105 to develop the majority of the dynamic systems and flight controls, while Kawasaki focused on the airframe and structural elements. On 13 June 1979, MBB’s prototype conducted its maiden flight at Ottobrunn, Germany; while the Kawasaki prototype first flew in Japan on 10 August 1979.

In the 45 years since, the helicopter has been continuously developed – a testimony to the quality of its original design. Airbus has delivered over 1,800 helicopters from the H145 family with the worldwide fleet recording six million flight hours.

A big-step upgrade was the EC145-T2 which debuted in 2011. The most obvious external change was that the T2 replaced the earlier models conventional tail rotor with a longer tail boom and a Fenestron tail. This was particularly welcome, as it prevents people who are loading cargo or patients through the rear clamshell doors from walking into the tail rotor. The T2 also featured a more powerful version of the Turbomeca Arriel 2E engines, rated at 894 shp each.

To the casual observer, it’s easy to dismiss the upgrades as small marketing changes, or even as just a name change for the sake of branding, from MBB to Eurocopter to Airbus Helicopters. The switch to a Fenestron tail rotor being considered the only noteworthy difference.  But progress has been steady, and the latest H145-B3 is far removed from the early BK117.

Airbus Helicopters first showed the 5-blade H145-B3 to the public at Heli-Expo 2019. The 5-blade development builds on the company’s Bluecopter environmental demonstrator, combining the performance of the additional blade with weight reductions to provide a remarkable 150-kg useful load increase. Airbus achieved the aircraft’s increase in useful load by reducing its empty weight by 110 lb. (50 kg) and increasing its max takeoff weight from 8,160 lb. to 8,380 lb. (3,700 kg to 3,800 kg).  At HAI 2019, Airbus pointed out that the useful load is almost the same as its empty weight.

The H-145’s new bearingless main rotor system features a fully composite flex-beam and main rotor blades, doing away with a main rotor system design that had been used on previous generations of the H145, BK117, and Bo.105. It dispenses with the main rotor head entirely, and the accompanying oil and grease needed to lubricate it.

In addition to providing increased lift with the latest airfoil design and material technologies, the blades have a unique foldable design that provides storage and potential cost replacement benefits.

For owners of the earlier 4-blade helicopter, there is an upgrade option through a retrofit for the EC145 T2. However, earlier versions without a Fenestron tail rotor are not eligible for the retrofit.

ON THE GROUND

On the ramp the helicopter is both substantial yet compact. The large slab sided fuselage gives a main rotor height of well over 2 metres, almost eliminating the chances of a main rotor strike.

The cabin can accommodate a 2-crew cockpit plus 10 passengers in a high-density arrangement or a spacious medivac configuration.

Thanks to its cabin size – versatility and load carrying capability, Airbus markets the H145 as being capable of performing a number of different missions, including aerial work, HEMS, energy support—offshore wind energy, as well as both offshore and onshore cargo and passenger transportation—law enforcement and private and business transportation. It has also gained a niche following as an aerial tender for super yachts. You can order an H145 with an interior worthy of carrying billionaires to floating pleasure palaces.

All the MBB-BK117 to H145 variants are powered by two Safran Arriel engines (formerly Turbomeca). The Arriel 1E2 engine is used on the C-2 and C-2e, and the Arriel 2E for the D-2 and D-3. On the H145, the engines have an upgraded takeoff power of 894 shp each.

Both the C-2 and C-2e were certified to the same 7,900-lb maximum weight. That was increased to 8,378 lb for the D-2 and D-3. However, the 8,157-lb and 8,378-lb maximum weights for the D-2 are described in the EASA type certificate data sheet (TCDS) as being alternative maximum weights, with the maximum weight of that variant without modification being 8,047 lb.

H145 airframes based on the D-2 and D-3 variants increase the usable fuel capacity in standard tanks to 239 USG. Airbus says that the H145’s maximum weight is the same regardless of whether or not it is carrying an external load, with a total useful load of 4,200 lb.

Apart from increasing the useful load and reducing complexity and thus maintenance, the five-bladed H145 was designed to substantially improve the ride quality and performance of the legacy BK117 rotor system, which was considered by many to have high vibration levels, particularly for aeromed applications. The 5-blade hub mounts the blades directly to the mast, making the system simpler, lighter, and easier to maintain than the original rotor mast head.

The switch to the 5-blade head involved modifying the forward crosstube and horizontal stabilizer to minimise dynamic reactions on the airframe. Also, Airbus removed light anti-vibration absorbers, and installed an electrohydraulic actuator to help the pilot check the freedom of controls on the ground when the engine is off.

The blades incorporate the latest aerofoil design to produce more thrust than previous aerofoil sections for the same power. While five blades have more drag than four blades, improvements to the aerodynamics of the rotor cuff of the blade have enabled the H145’s blades to generate more lift.

The blades can be folded backwards, simplifying storage. With the removal of just one of the bolts the blade can be rotated backwards to within the wingspan of the horizontal stabilizer. The whole process takes just 10 minutes.

Thanks to the folding blades, which allows all five to be turned rearwards to run in the direction of the tail boom, the aircraft’s potential footprint and storage requirements have been minimized.

The new blades have slightly changed the dimensions of the aircraft — it is now 10 cm taller and 10 cm shorter from the tip of the blade to the rear of the Fenestron. The diameter of the rotor disc has decreased slightly, from 11 metres to 10.8 metres.

Each blade is made of two parts: a metre-long ‘control cuff’ at the base of the blade that attaches to the mast, and the remainder of the blade, which attaches to the cuff through the two bolts. The cuff contains a composite flex beam — and it’s this that replaces all the bearings seen in a traditional main rotor hub.

In addition to allowing the blades to fold, having the flex beam situated in a separate control cuff provides for potential cost savings if a blade is damaged. So if for example a blade hits the wall of the hangar, then only the outer blade needs replacing and this is much less expensive.

Aside from its light weight and easy stowage, the new rotor system has many advantages over the legacy design which featured a maintenance-hungry titanium, oil-filled main rotor head with bearings. The new bearing-free system has no rotor head and requires no oil or grease and little maintenance.

The blades have no life limit, with replacement determined on condition.

THE CABIN

Although the maximum passenger seating capacity that is certified for all MBB-BK117 variants marketed as the EC145 and H145 is nine, MBB-BK117 C-2 airframes are able to carry 10 passengers if certain modifications are completed. According to Airbus Helicopters, possible configurations of the H145’s cabin include an eight-passenger layout—which features both forward and aft-facing seats, and is promoted as being ideal for offshore operations and passenger transport.

For law enforcement and military applications, the cabin can accommodate 10 or 11 personnel—in addition to 1 or 2 pilots—while one of the possible layouts for helicopter emergency medical services (HEMS) operators can carry a pair of stretchers, 1 or 2 pilots and as many as three medical personnel.

COCKPIT

All variants of the MBB-BK117 are certified for single-pilot operations, with the pilot flying from the right front seat.

Inside the cockpit, the H145 features Airbus Helicopters’ in-house-developed Helionix avionics suite that is promoted as improving the pilot’s situational awareness.

The H145 includes the installation of Airbus’s Wireless Airborne Communication System, which allows navigation and mission database information to be imported from a tablet and has the capability for cockpit Wi-Fi. On the ground, it can automatically export flight data and generate flight reports.

Apart from the 5-blade rotor, the H145 D2 to D3 upgrade addressed many of the user feedback requests.  These included improvements to the air conditioning, increased mast moment limits, some minor autopilot adjustments and automatic flight control system tweaks to address yaw oscillations while on steep approaches descending through ETL, and the addition of an auxiliary hydraulic pump for the flight control check.

IN THE AIR

While the five-bladed H145 D3 is a progressive improvement to the type, pilot reports note that, when combined with the large advances made with the D2, it improves the whole package and puts the aircraft in a class of its own.

As a medium-sized twin engine Single Pilot IFR (SPIFR), approved helicopter, a key objective was to reduce pilot workload. For single-pilot instrument flight rules making those operations not only safer, but exponentially more feasible for pilots with minimal actual instrument time making the transition to an IFR operator.

The engines are full authority digital engine control (FADEC) controlled, with a quick start procedure.

Standard Avionics include two Garmin GTN 750 touchscreen flight navigators, synthetic vision, better visibility, Helionix multi-function displays, and four-axis autopilot, not to mention the vastly increased performance and range. The H145’s maximum endurance and range—both of which are based on standard fuel tanks and sea-level altitude—are 3 hr. 34 min. and 351 nm, respectively.

The operating limitations of the H145 include a Vne of 150 kt, with a recommended cruise speed of 129 kt. The certified  maximum operating altitude is 20,000 ft.

Given that a key objective in the 5-blade upgrade was a reduction in vibration, it is relevant to note that while some vibration is still evident, particularly when passing through effective translational lift (ETL), vibration levels are dramatically reduced and mostly noticeable only when actively focusing on them. Pilot reports say, “If it’s not outright the smoothest helicopter I’ve flown, it’s certainly close.”

With the improved performance of the five-bladed H145 D3, any concerns about power go from being rare, to almost a non-factor for all but high-altitude mountain operations. Even there, the H145 D3 is capable of operating in many areas that were previously only accessible in high-performance single-engine helicopters such as the Squirrel AS350 B3, which landed on the top of Mt Everest (8850 metres). The H145 has been similarly tested, but just in the southern hemisphere, in the Andes, having landed on Aconcagua, at an altitude of 22,840 feet (6961m), setting an altitude record for twin-engine helicopters.

It maintains single-engine out of ground effect (OGE) hover capabilities throughout a substantial portion of the flight, leaving a good safety margins.

Training for engine failures in varying flight regimes is made easy using the ‘training button’ which creates an accurate simulation of a single-engine failure. At all but the highest of gross weights in an OGE hover, this is very much a non-event, and pilots report that “even then, it’s much less of an emotional moment than in many other twins. As someone who regularly conducts rooftop helipad operations in heavily congested metropolitan areas with limited escapes, this type of performance is comforting, to say the least.”

While the continuous development has improved the already impressive MBB / BK117 base, they have not made much difference to the cruise speed. The H145 is still most comfortable with a cruise of 120 knots.  Maximum range with no passengers is 351 nm and with full seats is 260 nm.

CONCLUSION

The H145 is a U$10 million helicopter and as such unfortunately it often challenges the limited budget of South African helicopter employers. For this reason, it finds limited use in South Africa, apart from its role in supporting offshore shipping, for which its twin engine, single pilot, IFR capability and compact size make it ideal.

While the five-bladed H145-D3 is a progressive improvement, when considered with the drastic advances made with the D2, it brings together the whole package and puts the aircraft into a class of its own. It may be a descendant of the venerable BK-117, but its performance, safety, and capabilities have improved so much that it will become increasingly difficult for operators to justify keeping the older models.