That new aircraft are often derived from earlier models is no surprise, but hybrids of two separate bloodlines are rare. The Eurocopter EC 145 medium twin, derived from the venerable BK 117 and the much newer EC 135, is one such hybrid. But unlike many mergers, particularly in the corporate world, this one actually works.
Like the BK 117C-1 before it, the EC 145 is a joint program between Eurocopter of France and Germany and Kawasaki Heavy Industries of Japan. In general, Kawasaki has responsibility for the lower and rear part of the fuselage while Eurocopter has responsibility for the front section, including avionics.
As explained to AIN by Philippe Marx, Eurocopter manager of police and parapublic applications, the program began in the early 1990s as a response to a French Gendarmerie request for a replacement for the Aerospatiale Alouette III. Eurocopter offered the BK 117C-1+, which had better high-altitude performance than the 117C-1, but budget cuts put the Gendarmerie’s buy on hold. In 1995 the Gendarmerie again requested proposals for an Alouette replacement, but with requirements beyond the capability of the 117C-1+. So Eurocopter and Kawasaki began working on what was then designated the BK 117C-2 and eventually became known as the EC 145. The Eurocopter EC 145 prototype first flew in Germany in June 1999, and the Japanese prototype flew in March 2000.
The $3.794 million (2003 dollars) EC 145 was certified by German authorities in December 2000 and by the FAA in February last year, but its first appearance in the U.S. was at this February’s Heli-Expo 2003 in Dallas. The model has also been approved in Japan (March 2001), France (June 2001) and Switzerland (2002), while single- and dual-pilot IFR certification was obtained in October 2001. The first EC 145 entered service in April last year with its launch customer, the Securite Civile (French Civil Defense and Emergency Preparedness Organization), which has ordered 32. Fifty-three have been sold to date and 15 delivered, all in Europe and the fleet leader has flown more than 1,200 hours. The first delivery to a U.S. customer, Lee County Medical, is scheduled for this September. Eurocopter plans to deliver 25 EC 145s this year.
At its Grand Prairie, Texas facility, American Eurocopter demonstrated the third production prototype EC 145 (tail number D-HMBM) to prospective customers, mainly aeromedical and law-enforcement operators, and the media during Heli-Expo and the whole of February and March. Helmut Rückert, Eurocopter chief pilot of civil flight testing, served as demonstration pilot. After five years in the German army flying Alouette IIIs and Bell UH-1Ds, Rückert joined what was then MBB of Germany in 1984. He has been with the company ever since, through its corporate evolution to become what is now Eurocopter, a wholly owned subsidiary of the European Aeronautic Defence and Space Co. During this time he has been involved in the development of the BO 105LS, BK 117B-1, BK 117C-1 and -C1+ (the immediate predecessors of the EC 145), the EC 135 and EC 145, so he is very knowledgeable of the EC 145 and its systems.
As the third EC 145 prototype (S/N 9003), D-HMBM was used for cockpit, avionics and preliminary certification flying. Although the model is FAA certified, the agency approved D-HMBM itself only for day-VFR demonstration flying in the U.S. Unfortunately, the weather on the morning of our planned flight was decidedly not VFR, but it improved enough in the afternoon to permit our flight. By the time we got into the air, the visibility was greater than 15 miles under a 1,500-foot overcast. Northerly winds gusted from 10 to 15 knots on the surface and were twice this at 1,000 feet. The temperature was a cold, un-Texas-like 43 degrees F.
During a detailed preflight walkaround inspection inside one of Eurocopter’s hangars (it was cold outside), Rückert pointed out the salient differences between the earlier BK 117s and the EC 145 that Marx had explained during our morning briefing. Most obvious is the cockpit from the EC 135, which includes the 135’s digital Thales MEGHAS avionics with color liquid crystal displays. With the goal of making it easier for pilots to transition between the EC 135 and EC 145, Eurocopter has embraced the “Airbus flight-deck philosophy,” Marx said.
A less obvious change is the helicopter’s composite main rotor blades, designed specifically for the EC 145. The blades are instrumental in giving the EC 145 a noise profile that is an average of 6.7 dB below ICAO standards for helicopters of this size.
Most of the rest of the EC 145–including engines, transmission, rigid main rotor system, conventional tail rotor and rear fuselage–are from the BK 117B-1 (and therefore C-1), with some improvements. Asked why Eurocopter didn’t opt for its signature, and arguably safer, fenestron tail-rotor for the EC 145, Rückert pointed out that at its lowest point the model’s tail rotor disc is 6.6 feet above the ground, providing good clearance for loading from the rear even with rotors turning. A conventional tail rotor also provides better high-altitude hover performance than a shrouded tail rotor, he said, and good performance at altitude was one of the requirements of both the French Securite Civile and Gendarmerie.
Inside the fuselage, refinements in the cabin have resulted in 213 cu ft of space and an unobstructed flat floor (50.8 sq ft), with four parallel tracks for mounting up to eight regular seats in a 3+2+3 seat arrangement, up to nine troop seats and various configurations with one or two stretchers. Not yet approved is an even higher-density 11-seat arrangement for parapublic use only. Compared with the BK 117C-1, cabin length has been increased from 8.4 feet to 9.7 feet and the width has increased seven inches to 5.4 feet at shoulder level. The BK 117’s popular rear clamshell doors are maintained and supplemented by large sliding doors on each side of the cabin, where the posts were removed to improve access.
Also eliminated was the BK 117’s center post behind the cockpit seats, which housed the actuator rods for the cyclic and collective flight controls. Pilot control inputs are now transmitted from the cyclic, collective and pedals via flexible cables routed through a narrow housing up the center of the windshield to the hydraulic actuators in the roof of the cockpit, a first for a helicopter, Marx said. The actuators are operated by the aircraft’s dual, 1,500-psi hydraulic system.
Rückert explained that strategic placement of oil reservoirs and the addition of inspection windows in cowlings makes it necessary to open cowlings only during the first preflight inspection of the day. After that, everything the pilot needs to check during the walkaround inspection can be viewed without opening any cowlings.
Not surprising for an aircraft targeted first for the parapublic markets and subsequently for aeromedical, utility and other markets, the EC 145 comes with a slew of options for nearly any conceivable mission. Considering the equipment available–rescue hoists, search lights, flotation gear, snow skids, night-vision-goggle compatibility, aeromedical stretchers and associated equipment–D-HMBM, with but a few seats in the cabin and standard cockpit instrumentation, was relatively unadorned.
Flying the EC 145
Starting the EC 145’s Turbomeca Arriel 1E2 turboshaft engines is straightforward but somewhat more involved than the “one-button starts” of helicopters equipped with a FADEC. Rückert called the EC 145’s start “semi-automatic” in that it requires some manual throttle control by the pilot to keep the engine’s turbine outlet temperature (TOT) within its starting limits. The good news is that the well designed vehicle and engine multifunction display (VEMD) provides clear and understandable indications to the pilot at all times. (The VEMD provides indication of engine oil temperature and pressure, torque, TOT, gas generator speed [N1], main gearbox oil temperature and pressure, dual generator and battery amperage, outside air temperature and rotor mast moment.)
The engine start, which is the same for both engines, is as follows: set engine twist grip to a 20-degree setting (as indicated on the grip); press and hold the start switch; wait for the first-limit indicator to move, indicating an increase in TOT; adjust the twist grip to control increase in TOT and keep it within 550 to 650 degrees C. (Max TOT permitted is 785 degrees C for start and 865 degrees transient). Following engine start, tests of the hydraulics, stability augmentation, autopilot, engine fire-extinguishing and other systems follow in logical order.
Normal start is with the rotor brake off, and the EC 145’s rigid rotor permits engine starting and rotor engagement in wind up to 50 knots. We started with a 15-knot tailwind, although we were protected somewhat by the Eurocopter hangar behind us. Rückert monitored the controls as I lifted into a hover.
The right skid comes off the ground first, but only barely before the left skid, giving a nearly level hover attitude. We were relatively light, only 6,512 pounds at takeoff (mtow is 7,904 pounds, an increase from the BK 117C-1’s 7,385 pounds), so we had plenty of available power. The Arriel 1E2s are rated at 738 shp for takeoff with both engines operating, and we needed about 70-percent torque in the hover.
The torquemeter, however, is not the pilot’s primary focus. Rather, it is a gauge Eurocopter calls the first-limit indicator, or FLI. This gauge combines the inputs of torque, TOT and N1 into one digital needle on the vehicle and engine malfunction display. The pilot needs only to keep this one needle within limits to avoid exceeding the limits of the above three parameters.
The EC 145 exhibited amazing stability in the hover, even in gusty side- and tailwinds. During hovering turns left and right I noted little weathervaning.
For a normal takeoff, one increases collective by 0.5 (on a scale of one to 10) above hover FLI. Stable and smooth are good descriptors of the takeoff, with very little vibration through translational lift. In fact, throughout my two demonstration flights, which included a dash to the 150 knots (max permissible speed for conditions), vibrations were minimal, even though two dampers below the cockpit floor in D-HMBM were inoperative.
As the EC 145 accelerates through 55 knots, an electronic system linked to the fuel management system uses main rotor torque to reduce rotor rpm from 101 percent to about 96 percent, a major noise-reducing factor. Conversely, as airspeed decreases below 55 knots, rotor rpm automatically climbs back to 101 percent. For Category A operations, the pilot can manually select a higher rotor rpm (103.5 percent) for greater power. Normal climb speed is 65 knots. We leveled at 500 feet pattern height and used 80 knots as a comfortable speed downwind.
On landing, the EC 145 allows considerable variation in approach angle without the penalty of increased vibrations. I noted little difference in control or vibration level during both shallow and steep approaches at Grand Prairie and at the Dallas Vertiport, where I flew a simulated rig approach and stopped in a high hover before sliding onto the pad. The wide cockpit and narrow instrument panel provide an excellent field of view, particularly valuable for confined-area and elevated helipad operations.
The EC 145’s Category A procedures from a clear heliport specify a takeoff decision point at 20 feet and 30 knots, and landing decision point at 100 feet and 40 knots with rate of descent 500 fpm or less. For elevated heliports, landing decision point is 100 feet and 30 knots with rate of descent 300 fpm or less. Maximum-performance takeoffs–from a confined area, for example–are accomplished with a vertical climb to clear obstacles (60 to 100 feet) followed by a five- to 10-degree nose-down attitude to gain airspeed.
In cruise, Rückert demonstrated the operation of the three-axis autopilot and its indications on the primary flight display. (A fourth axis would provide control of the collective.) Flight is possible with one hydraulic system inoperative (to land as soon as practicable), but not permitted in training. However, flight with the autopilot switched off and with both the autopilot and stability augmentation system switched off is permissible, and not that much different from flight with the systems on, at least in cruise.
We also flew with one engine at ground idle, but at our relatively low weight and low outside air temperature, this wasn’t much of a test. Nor was our autorotation to a power recover, but then autorotations in a twin are not as critical as in a single-engine helicopter. Descent rate during the autorotation was about 2,200 fpm.
Conclusions made after less than two hours in any aircraft must always be taken with a grain of salt. With that said, except for its lack of a FADEC, it’s hard to find fault with the EC 145. Eurocopter has again taken a well proven design and made it into an even better helicopter. Time and operator experience will likely uncover some undesirable characteristics, but on the surface–and even a bit below the surface–it appears to be an excellent aircraft for its market.