Eurocopter's new light helicopter - the EC130 - is claimed to be the quietest in its class
Peter Gray/ANAHEIM, CALIFORNIA
Following last month's sneak preview of the Eurocopter EC130, Flight International flew the light helicopter at the Heli-Expo in Anaheim.
My pilot was Eurocopter experimental test pilot Didier Delsalle. Also present was flight test engineer Bernard Certain and programme director Xavier de la Servette. The weather was standard ISA at sea level with a light wind. Take-off weight was 330kg (725lb) below the maximum of 2,400kg since, unlike at the factory, it was not possible to ballast the aircraft.
Looking round the EC130, I noted the wide, spacious cabin, able to seat seven or eight passengers instead of the seven allowed by its predecessor, the Eurocopter AS350B3. The centre of gravity limits had to be expanded to contain this but now passengers can sit where they want. In extreme cases, the battery can be moved to its second location to balance the aircraft.
Vertical space is reasonable - you would have to be over 6ft (1.83m) tall to hit your head on the roof, even though the rear four seats are elevated to increase passenger external visibility. The elevation platform can be easily removed with the seats if a flat floor is required for cargo. The Agusta A119 Koala is the only other helicopter among the EC130's nearest rivals that can carry eight - the Bell 407 seats seven. With eight on board the EC130, maximum fuel has to be reduced to 50% and with seven it is 80%.
The empty weight has inevitably increased over the AS350B3 to support the heavier Fenestron tail rotor, a penalty of about 150kg. To compensate and to take advantage of the good performance, the maximum take-off weight has also been increased, from 2,250kg to 2,400kg. The EC130 with full fuel has a useful load of 485kg, compared to the AS350B3's 570kg, the Koala's 575kg and the 407's impressive 620kg.
For casualty evacuation, the EC130 can carry one pilot, two stretchers and two attendants or two pilots, one stretcher and two attendants. The lower power-to-weight ratio and larger cabin compared with the AS350B3 reduces the maximum cruise speed (127kt (235km/h) against 140kt) and lowers the inside and outside ground effect ceilings. But these are still a respectable 10,720ft and 8,740ft - not too different from the Koala and 407. If you want better hot, high and heavy performance, choose the AS350B3 (13,285ft and 10,825ft). The 407 cruises at 128kt and the Koala at 136kt. All these figures are for maximum weight at sea level on a standard day.
The EC130 has more baggage space (just over 1m³) than any of its competitors and its smaller brother, though the space is divided into three separate bays. Underslung load work requires good out-of-ground effect performance. Older generation helicopters struggle with heavy loads, these latest models do not. They will all carry the maximum load allowed on the hook. I noted the newly designed undercarriage with its profiler on the rear strut to give it good stability.
The Turboméca Arriel 2B1 engine is the same as the AS350B3's except for several key differences: not only are there two full authority digital electronic controls (FADECs) to manage it - though only one fuel valve - but also a back-up fully independent fuel control box that automatically controls the engine in the unlikely case of a double FADEC failure (belt and braces). So the twist grip throttle on the end of the collective lever becomes largely redundant, useful perhaps to wind off RPM in the event of a tail rotor failure or to practise autorotation. If the pilot inadvertently winds off the throttle, it automatically winds itself back to the flight stop, once released.
All of the EC130's competitors and the AS350B3 have either a single FADEC or, in the Koala's case, a single electronic engine control with a manual throttle in case of failure. This requires extra training and practice.
Another unique feature of the EC130 is its two independent hydraulic systems. This is an important improvement on all competing aircraft which have either one, or, in the Koala's case, two, but one for the tail rotor pitch change.
The key to less noise
I noted the newly designed tailboom, drive shaft and tail gearbox. The Fenestron, similar to the EC135's with the unequally spaced blades, is the key to less noise. Eurocopter claims that this aircraft is the quietest of its class and is well below all the limits set by the various authorities including the Grand Canyon National Park, which is the most stringent.
The other significant noise reducer is the rotor RPM (NR) automatically reducing from 400RPM in the hover to 386RPM in the cruise. The tip of the advancing rotor blade experiences not only its revolution speed, which can be as high as 500kt (925km/h) but also the aircraft's forward speed. As the aircraft exceeds 100kt, the advancing tip approaches Mach 1 with all its associated problems, including noise. The oddly shaped main tips on some high-speed helicopters are attempts to address these problems. This NR reduction is cleverly managed by the FADEC and is not noticed by the pilot. Conversely, NR increases as the aircraft comes to the hover.
All the energy-absorbing seats inside had high backs and dual shoulder harnesses. None of the competitors are as well equipped.
I sat in the comfortable left-hand pilot's seat. Eurocopter has chosen this seat for the pilot instead of the conventional right-hand position to eliminate interference with the collective lever by passengers or internal freight (although this should not happen if the load is secured properly). It also offers a better position for vertical reference operations when the pilot must lean out and watch the load on the end of the line below. You cannot do this from the right-hand seat in the AS350 as the seat is too far from the ledge. Eurocopter compromises in these helicopters by providing a window in the floor by the pilot's seat, but it is nowhere near as effective.
Most other helicopter manufacturers offer a choice of avionics and instruments. This can take extra time to fit, undoubtedly at extra cost. Eurocopter has decided to fit a standard comprehensive package, only just short of IMC (instrument meteorological conditions) standards. The avionics are integrated. For example, the two navigation systems are linked to the horizontal situation indicator (HSI). The GPS satellite navigation has a moving map display. Some competitors charge extra for such essentials as an attitude indicator, directional gyro, vertical speed indicator or turn and bank - all are standard in the EC130.
The Thales Avionics vehicle and engine multifunction display by is the same model as the one I liked in the AS350B3. It reduces the clutter on the instrument panel to a simple display, telling you all you need to know at the time. I particularly like the first limit indicator (FLI) which monitors torque, turbine exhaust temperature and compressor speed and shows you with one indication at a glance which one is highest and how much you have in hand. Consequently, the compact instrument panel allows excellent forward and downward visibility and there is plenty of available space on the right of the panel for whatever extras the operator requires.
To complement the attention to detail there are two fairly large map pockets under the panel. Overhead there is only the rotor brake (standard equipment) and an emergency fuel shut-off, allowing good overhead visibility. This is important when coming vertically out of a jungle clearing. All eight occupants can talk to each other over their headsets, though the noise level was comfortable when I removed my own headset in flight. As is usual in small helicopters, the pilot's seat and pedals can be adjusted only fore and aft but I found a comfortable position. The cyclic stick and collective lever (the lever) are nicely balanced and have their own friction devices, though there is built-in friction.
There have been incidents in which the pilot has moved the helicopter or even taken off with the external power unit still attached. To avoid this, I always check to see if the pilot can see the connection point on the fuselage. You cannot in the EC130 but there are two warning lights.
Typical FADEC start-up
Start-up was typical FADEC - fuel pump on, select start and watch. You can start in idle or flight modes. We were parked fairly close to two other helicopters, one each side, facing the hangar so requiring a rearwards exit to the taxiway. But Delsalle had such confidence in his machine that he allowed me to come to the hover, look over my shoulder and back out. Once backed out and before hover taxiing, a quick glance at the FLI showed me how much power I was using and how much I had in hand, freeing me from having to remember torque, temperature or compressor limits. We headed south to the beach then west to follow it. I trimmed for straight and level and released all the controls. The aircraft, which is not equipped with a stabilisation augmentation system, continued straight and level.
Delsalle and I then had some fun by leaning in the same direction to turn it. Delsalle took control and pulled into the transient excess power level. After 1.5s we had a warning light. Since this was within transient limits it was not recorded; any outside limit excess would be.
I came to a 1,500ft hover, trimmed and released the controls. Even with no artificial stabilisation the aircraft remained stable - an impressive demonstration of good dynamics. Some 360° pedal turns were equally stable. Maximum continuous power at this altitude, the EC130 now 360kg below maximum weight, gave us 135kt IAS/TAS. A slight dive took us to the VNE of 155kt. There was hardly any noticeable increase in the vibration level, which was already benign (there are three anti-vibration systems installed) and likewise a 45° turn to the left followed by a swift 60° turn to the right. The rotor was crisp. Delsalle pulled the nose up vertically and performed a graceful "wing over". All this demonstrates excellent rotor characteristics. Thereafter 90° steep turns in both directions at 120kt were a formality. However, the limit light came on as a gentle warning not to go too far. Slowing to 100kt and going over thevertical, the light stayed out.
Sudden engine failures still occur and over-relaxed helicopter pilots let the NR get too low before reacting. So I always check rotor droop and time available in a single engined helicopter by having the engine suddenly reduced to idle in the cruise, doing nothing and watching NR. The EC130 allows 3s, which should give plenty of time for even the slowest pilot to realise what has happened. A distinctive and loud audio warning is heard, and a red warning light comes on. The FADEC recovered the engine quickly to flying RPM.
Another potential killer in helicopters (and also in tilt rotors) is vortex ring/settling with power, which can trip up even experienced pilots, as happened in one of the fatal Bell Boeing V-22 Osprey accidents. Some helicopters will literally drop into the condition easily and quickly and before the pilot has realised what is happening, will hit the ground excessively hard, because it usually occurs close to the ground - just like the stall of a fixed wing aircraft turning onto final approach when the pilot overdoes the angle of bank. So I like to evaluate the lead up to the condition: looking for warning signs such as how much control there is, and the effect of the recovery actions (at least 20-25kt IAS, then raise the lever to control the loss of height or, if height permits, enter autorotation, then build some airspeed).
The EC130 gave us all the warnings - a significant increase in vibration levels, yawing, increased rate of descent. Delsalle, with his vast experience of the Ecureil/Squirrel family, flew out of the condition quickly by lowering the nose and simultaneously raising the lever to contain the height loss. We were at a safe height. So while there is plenty of warning if the pilot recognises it, there is also plenty of control to enable the pilot to recover.
Around the airfield
Continuing our upper air work, I asked Delsalle to raise the lever from fully down to a high power setting as quickly as he dare while I checked NR and engine response. The helicopter recovered from the slight droop in less than one second. I then invited him to dump the lever from a high power setting. There was no droop.
We arrived at a satellite airfield and I carried out a steep approach to the hover and landing. Downwards and forwards visibility was excellent, as expected. I did not have to yaw the nose sideways to keep my landing area in view all the way down. Similarly a vertical climb to 100ft and back down allowed excellent outside references to keep the flight path vertical.
Using the GPS for a groundspeed check, I flew sideways to the left up to 48kt before I used full right pedal. Sideways flight to the right at 40kt still had a little more left pedal remaining. Modern helicopters do not suffer the nose down pitch, often severe, accompanied by excessive rearwards stick application of earlier designs, so I confidently roared backwards at high speed. Delsalle demonstrated his usual high speed spot turns where the sideways G force can be felt and the outside world starts to blur.
All these manoeuvres, while not used in normal operation, give the pilot confidence he has enough main, Fenestron and engine power to deal with strong wind from any direction.
A 65kt autorotation gave a rate of descent of 1,900ft/min (9.6m/s) - anything under 2,000 is satisfactory. A powered recovery to the hover showed how effectively the FADEC can accelerate the engine. There was no opportunity to take the aircraft to its out of ground effect hover height so I had to rely on Delsalle's observations, particularly the amount of Fenestron power available, which he said was ample. The aircraft is cleared for 6° of up and down slope and 8° sideways, though Delsalle says that 10° is not a problem.
We returned to our landing position, idled the engine for 30s, switched off the FADEC and applied the sliding lock on the lever. Delsalle interrogated the VEMD to extract flight and engine power details, and examine for any exceedances or failures (there were none). It will also provide technicians with peripheral maintenance information.
The EC130 proved Eurocopter's design objectives. It is indeed comparatively quiet, both inside and out. The cockpit/cabin is roomy, the outside visibility excellent and the ventilation/heating/air conditioning satisfactory.
Eurocopter has used its vast experience (the Ecureil family has accumulated over 11 million hours) to provide reliable components with high time between overhaul. Commonality with other models has been addressed. All this means that development and operating costs have been minimised. Eurocopter's other aims of good finish and performance have also been achieved.
As an aviation safety advisor to many of the world's largest oil and seismic companies, I appreciate the built-in safety features such as crashworthy seats throughout and dual shoulder harnesses, dual hydraulics and FADECs with the additional back-up system. The Fenestron should minimise or even prevent damage should the pilot get too close to ground objects (not uncommon on seismic operations). Someone walking into it may well escape unharmed. Based on experience with their previous models, Eurocopter expects maintenance hours per flying hour to be somewhere between 0.3 to 0.53.
Pilots will appreciate the EC130's handling characteristics while operators should benefit from the cost effective features. Passengers will enjoy the comfort and, most importantly, those on the ground the low noise signature. The EC130 is a useful complement to the rest of the Eurocopter fleet.
Source: Flight International