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Wednesday, September 1, 2004

Helicopter Intellect

Eurocopter's Super Pumas have always had plenty of brawn. The new EC225 brings in the brain.

Douglas W. Nelms in Marignane, France

Eurocopter appears to have two basic philosophies that have served it well. The first is that there is no such thing as too many models to offer its customers. The other is that if you have a good thing, stick with it while you're making it better.

Hence the EC225/EC725.

The newest member of the AS332 Super Puma family, the EC225 follows the civil AS332L1/L2 and military AS532 as a result of the French military asking Eurocopter to produce an aircraft aimed at the Combat Search and Rescue role, but with greater power, longer range and better able to sustain battle damage than their current AS532 Cougars.

Eurocopter has now exceeded that expectation, producing an aircraft that not only outperforms the capabilities of the earlier models, but also has advanced avionics that greatly increase the pilot's ability to perform the medium to long-range offshore and SAR/CSAR missions.

The request from the French military was made in the mid-1990s, leading to a Eurocopter decision in 2000 to develop the new aircraft based on the AS332L2 but with new mission equipment, autonomous avionics and upgraded engine and transmission systems. First flight on the new aircraft was October 3, 2002.

The decision was also made to cross develop civil and military versions of the new aircraft simultaneously--although Eurocopter has not officially designated the new civil version a "Super Puma." Instead it is simply called "an advanced member of Eurocopter's 11 metric tonne class, mid-range Super Puma helicopter family." A subtle differentiation.

However, the military version EC725 will be called a Cougar Mk II, based on the 1989 Conventional Armed Forces in Europe (CFE) treaty designating the number of military weapon systems the signing states could produce. This required manufacturers to separate civil and military versions of the same model aircraft.

The French forces have already ordered 14 EC725s, with five scheduled for delivery this year, seven next year and the last two in 2006. "The target is around 20," according to Richard Dubreuil, Super Puma directorate, new development manager. The first combat search and rescue EC725 is scheduled for delivery this month.

One VIP-configured EC225 is also scheduled for delivery this October, going to a head of state. Three EC225s are scheduled for delivery next year, with two going to Bristow Helicopters and the third going to a VIP customer. Bristow already operates 29 AS332 Super Pumas in its worldwide fleet and will receive its first EC225 next June. It has also placed options on two additional EC225s.

Base price of the civilian EC225 runs between 12 million to 13 million euros (roughly $14.8 million to $16 million), with an additional two to three million euros ($2.5 million to $3.7 million) for customized equipment, all based on what the customer wants, Dubreuil said. The military EC725 can cost in excess of 20 million euros because of the need for specialized equipment, he said.

Certification work on the new EC225 is being accomplished by the French DGAC, with final certification from the European Aviation Safety Agency (EASA) based on JAR 29 regulations, Dubreuil said.

The EC225 received its full IFR EASA certification, to include single pilot IFR, in July and expects to receive its de-icing certification early next year. Application has already been made for FAA certification, expected in mid-2005.

Last June, Eurocopter invited Rotor & Wing to visit its production facilities in Marignane, France, to fly the new EC225. The visit started with a tour of the facilities, where all three versions of the Super Puma family (AS332L1, L2 and EC225) are in production. Touring the facility allowed an opportunity to visualize the physical differentiations between the three models, as well as note some fairly significant changes that are also being made to the AS332L2.

Following a survey of its customers, particularly its offshore customers, Eurocopter is offering as an option a version of the EC225 with larger cabin windows. The standard cabin windows are being increase by more than 50 percent, to 42 cm. (16.5 in.) by 69 cm. (27.2 in.), while emergency exit windows are being increased to 28 in. by 19 in. All the windows can now be used for emergency exits by offshore oil workers in bulky clothing. These new larger windows are also being offered on the AS332L2

The most obvious difference between the AS332 and EC225 is the rotor system. Using technology developed for the EC155, Eurocopter has developed a next-generation five-bladed spheriflex main rotor system for the EC225, designed to increase lift capability and speed while reduce vibrations.

Eurocopter also upgraded the engine and main gearbox, giving it 14 percent more power than its immediate predecessor. The EC225 is powered by twin Turbomeca Makila 2A engines rated at 2,413 shp for maximum emergency power/one engine inoperative, 2,100 shp for take-off power and 1,870 shp maximum continuous. This compares to maximum emergency power/OEI rating of 2,109 shp for the Makila 1A2 powered AS332L2 and 1,877 shp for the Makila 1A1 powered AS332L1. The engines are composed of modules that can be replaced independently for ease of maintenance.

A significant advancement for the more powerful Makila 2A powerplant system is its two-dual channel FADEC fuel controllers with a backup system that automatically reconfigures in case of a single-channel failure. For super redundant safety the system also allows manual reconfiguration after a dual-channel failure of one FADEC system. Eurocopter said that this makes total governing failure of an engine impossible.

While the main gearbox has been redesigned and reinforced for greater power and safety, the key benefit for the pilot is a guaranteed 30-min. "dry run" capability. And while it is certified to run dry for 30 min., actual tests have taken it up to 52 min.

Dubreuil said that the EC225/725 is really considered an "AS332L2 Plus." Although the EC225 will have major system upgrades such as power plants, rotor system, main gearbox and avionics, it will keep several systems generic to the AS332L2. These include the electrical and hydraulic generators, landing gears, fuel system, intermediate gear box, tail rotor and most of the optional equipment such as APU, radar, flir, radios, electronic warfare equipment, hoist and internal layout.

The primary markets for the civilian EC225 are expected to be offshore, fire fighting, VIP/Heads of State and search and rescue, while the military role for the EC725 will primarily be CSAR and special operations, he said.

While production of the civil and military versions of the current Super Puma fleet is split about 50/50, it is expected that the EC225/725 will most likely be tilted to the civil side, Dubreuil said. He noted that 40 percent of the total aircraft production will be going toward military troop transport, 23 percent will be for the off-shore market, 17 percent for the SAR/CSAR role, 12 percent for the VIP/Head of State market, and a final 8 percent for naval operations. Completion of a single aircraft takes between 12 to 18 months, "depending on the customization requirements," he added.

Although the aircraft I got to see in the production process were the civilian versions, the defensive systems being put on the EC725 aircraft have been proudly displayed at previous air shows. The philosophy behind the defensive system is (1) avoid detection, (2) if detected, avoid getting hit and (3) if hit, avoid going down. For the first element, the aircraft has a cockpit fully compatible to night-vision goggles operations, as well as infrared suppressors. It is also designed for nap-of-the-earth operations.

If case the aircraft is detected, it carries radar-warning receivers with missile approach warning systems, laser detection equipment, and chaff and flare dispensers. Finally, if it is hit, the EC725 has engines that have the dual FADEC, triple overspeed sensors, engine blade shedding protection and dual fire detection/extinguisher systems. The pilots' seats and cabin floor are armored, fuel tanks are self sealing and crashworthy, the hydraulic system is triple redundant with dual channels and the rotor blades are impact tolerant through a multibox construction structure. And, of course, there is that 30-minute dry run main gearbox.

For the EC725 that wants to fight back, the aircraft can be equipped with manually operated 7.62 mm machine guns firing out each side of the cabin, plus two armament pods that can each carry 20 mm. guns or 19-round 2.75mm rocket systems.

Flying the Med

The day of the flight was a beautiful, southern France sort of day, perfect for flying. Eurocopter's main headquarters and production facilities are just north of Marseilles, so our test flight would primarily be done over the blue waters of the Mediterranean. I was flying right seat with Harv� Jammayrac, a Eurocopter experimental test pilot in the left. Supporting the flight were Daniel Semioli and Bernard Tureat, flight test engineers.

One of the things I absolutely liked best about the EC225 was simply getting into it. Most medium/heavy lift helicopters require the pilots to get into the cockpit through the main cabin. This means the pilot first has to lift one leg over both the center console and the pilot's seat, then figure out where to place it while he gets the other leg over so he can get settled into the seat without looking like a complete fool. This is easy to do for a young warrior just out of flight school. For those of us who have been around a while, it isn't.

The entrance to the EC225 cockpit is from the outside, same as for most small helicopters. Open the door, grab a handle, put your left foot into a foothold and climb up and in. Little trickier getting out since you need to know where that foothold is.

The cockpit is spacious, with fully adjustable seats, hence a comfortable and relaxing "front office." After getting me fully strapped in with the five-point safety belt, Jammayrac introduced me to the true marvel of the aircraft--the avionics.

Dubreuil had advised me that the EC225 has a third-generation avionics glass cockpit package designed for the SAR/CSAR role and long-range off-shore activities. The first generation avionics were those developed for the AS332L2, while the second-generation avionics are in the NH90.

The helicopter's Advanced Flight Display System consists of four 6X8 in. multi-function active matrix liquid crystal displays (AMLCD) and two 4X5 in. VMS (vehicle management system) engine instrument displays. It also has a 5-in. square integrated stand-by display that is a back-up for virtually anything within the avionics suite.

The navigation/flight data display system was developed for the EC225/725 by Kollsman, Inc. and designed to allow the pilot to scan it quickly and easily. The flight data information is provided on a horizontal line bisecting the artificial horizon in the center of the flight/navigation screen. Air speed and altitude figures move up or down the screen on each side, so that the pilot only needs to scan the horizontal center line to determine his airspeed or altitude while simultaneously determining his angle of bank or if he's flying straight and level. The figures are also given digitally elsewhere on the screen as a backup.

The multi-function display also has an elliptical Horizontal Situation Indicator developed by Eurocopter. The elliptical nature of the indicator provides an almost 3D view of the compass, increasing the pilot's situational awareness of his course heading and navigational settings.

Each pilot has his own two multi-function screens which can operate in unison or totally independent, depending on need. The flight display screens are menu-driven to provide mission management information as well as flight data such as navigation and communication. It also has an open hardware/software architecture to allow for future upgrades as they become available.

Jammayrac noted that if any portion of the main flight data screens or VMS screens fails, the information can be called up on the integrated stand-by instrument display.

The system also allows a pre-programmed mission computer chip to be put into the avionics system to further reduce the workload on the pilots.

Not withstanding the wonders of the avionics and flight displays, the first thing I wanted to do was simply get a feel for the aircraft--to see how well it handled.

Jammayrac lifted off from the Eurocopter helipad at Marseille Marignane Aeroport and flew us to a smaller general aviation airport a few miles north. He then turned the aircraft over to me for some basic hovering and hover-taxi work, then a couple of flights around the pattern.

Not surprising, the EC225 flies like a dream. I admit there are few helicopters I've met that I didn't like, but this aircraft seemed particularly responsive and quick to the touch. Eurocopter claims that it is designed for high-speed, nap-of-the-earth flying to avoid detection by the bad guys. I believe them.

After a couple of trips around the pattern, I set up a steady hover and Jammayrac put in the hover-hold autopilot. It pretty much held rock solid. What little movement it had was sufficiently insignificant to be ignored. Jammayrac then dialed in sidewards hover speed and the aircraft went into a sustained, hands-off fixed speed sideward flight. After bringing it back to a stable hover, he programmed in a fully automated takeoff from the hover, climbing out to a predetermined altitude and leveling off. The truly amazing thing was that while I was theoretically "flying" the aircraft, my feet were totally off of the pedals. Torque control was handled automatically by the avionics system.

Once out over the Mediterranean, we flew up and down the coast a bit to experience the aircraft in normal flight regimes. A key element of the aircraft's flight characteristics is its lack of any significant vibrations. With an almost five hr. maximum range, this lack of vibration becomes a key element in both pilot and passenger comfort.

The EC225 uses an active vibration control system developed by Eurocopter working in conjunction with Cary, N.C.-based Lord Corp., which provided the basic equipment. This system uses anti-vibration actuators and a power amplifier to reduce the vibration level to virtually zero.

"It is a system in which you use vibration sensors to measure the vibrations in the (aircraft's) structure. That information goes in a computer that analyzes the information, then uses the actuators to counteract the vibration," said Guy Billoud, general manager for Lord S.A., based in Toulouse. "A vibration is like a wave. If you add to this wave an actuator, which is like a shaker, the shaker will anti-wave the structure, putting an anti-wave on top of the vibration. The two result in a reduced vibration." In essences, the anti-wave is the exact opposite frequency of the vibration wave, so they cancel each other out.

"The important thing is to have an amplifier that is highly efficient. Typically, your hi-fi amplifier runs on the order of 10-20 percent efficiency. You cannot allow that in an aircraft, so there is specific technology called Class-D that allows you to have 80-90 percent efficiencies. That is what we have developed for this program," he said.

The anti-vibration system is actually designed to reduce the vibration levels at lower speeds, Dubreuil said. The five-bladed rotor system "is very compatible for anti-vibration. At very low speeds, between 80-120 kt., the vibration increases slightly, but above 120 kt. to 180 kt., the vibration decreases and smoothes out. The active anti-vibration system was installed for the 80-120 kt. range." Dubreuil also mentioned that while the anti-vibration system is an integral part of the aircraft's systems, it is not a "go-no-go" item on the minimum equipment list (MEL).

Once I had had a chance to check out the much-touted anti-vibration system, Jammayrac showed me the autopilot capabilities of the aircraft. The EC225 has a digital four-axis SFIM Inc. APM 2000 autopilot currently certified for the EC135, EC145 and EC155. This allows a dial-in capability generally reserved for corporate jets and airliners. Along with keeping the aircraft on any airspeed, altitude and heading programmed into it, it allowed Jammayrac to simply dial in new heading and altitude, and the aircraft went there. The APM 2000 is also fail-safe. According to the manufacturer, no single failure can result in a major attitude deviation. A key element put into the aircraft to support the SAR/CSAR and off-shore mission, the autopilot is a major step up from the two- and three-axis autopilots now generally available to the helicopter industry ("Hands Off", April 2004, page 50).

The autopilot also helps stabilize the aircraft. With the autopilot turned off, the controls become overly sensitive and a bit squirrelly. With it, the controls are very smooth and responsive, ideal for the special operations low-level or nap-of-the-earth mission. Also for landing on small platforms in bad weather.

After getting a very good demonstration of those capabilities, Jammayrac had me bring the aircraft to an out-of-ground-effect hover. Again it was very stable with no effort required to maintain the hover with full pedal authority, although admittedly we were fairly light at 18,635 lb. out of a total maximum all-up weight of 22,930 lb. Plus the wind was light.

Again Jammayrac put it into hover hold and again it held rock steady. He then pulled back the power on one engine. The fail-save FADEC system is designed to automatically kick in maximum power to the remaining engine. So if an engine fails during an OGE hover, the pilot simply presses the go-around button and the remaining engine takes up the slack while the aircraft starts an automatic climb-out and forward flight. Rotor RPM is maintained by automatic adjustments to the collective.

"But if the pilot does nothing, the (good) engine will accelerate to OEI rating as before, trying to compensate for the loss of power to the other engine. But if (collective) control inputs are not made, it will result in rotor RPM decay and descent of the helicopter," Jammayrac said.

The aircraft is also fail-safe for descents. With a large number of EC225/725s operations anticipated to be over water, the aircraft is programmed to stop any unplanned descent at 80 ft. should the pilots become disoriented, inattentive or simply lose the horizon. "This automatic feature is active as long as the indicated airspeed, vertical speed or glide slope mode of the autopilot is engaged. In that case, the autopilot will automatically engage the altitude mode to achieve a level-off at about 80 ft. When you are making a (normal) descent to the ground, you are not using those modes. The idea is to protect against a continue descent when you are hands-off of the controls," he said.

The autopilot has one other capability for the SAR/CSAR role that I found to be a pretty sexy thing. After demonstrating the capability of the aircraft to not fly into the water, we climbed back to about 1,000 ft. altitude and went looking for a buoy that would represent a ship in distress or a downed pilot.

When we found one, we flew directly over it and Jammayrac punched in the FTDN, or Fix and Transition Down, button. At that point the aircraft was on its own. Without any further action on the part of the pilot, the aircraft fixed the position and sent it to the flight management system. That system then calculated a flight pattern that would position the aircraft over the point and facing into the wind. With the flight pattern established, the autopilot took over and flew the aircraft outbound from the buoy, then turned back inbound, heading into the wind using its area navigation mode. At the Transition Down point, the autopilot began reducing the airspeed and altitude to bring the aircraft to a hover about 0.1 mile from the pre-determined point--in this case the buoy. The only thing the pilot needs to do is select the hover height, although the aircraft is defaulted to 100 ft.

Once over the point, the flight engineer can take control of the aircraft from the cabin, positioning it as necessary to accomplish the mission.

Flying back to Marseille-Marignane Aeroport, Jammayrac called the tower, requesting a full ILS approach. He then programmed the appropriate information into the computer and we all sat back and relaxed. The aircraft did all the work, flying toward the airport, intercepting and turning onto the glideslope, initiating descent at the appropriate point and flying down the glideslope to a point roughly 30 ft. above the runway at 30 kt. The only disconcerting thing was that on final the nose of the aircraft was pointed about 30 degrees to the left, a bit radical for a pilot who was taught to always have the aircraft pointed straight down the runway.

The only difficult thing I saw about the aircraft would be learning how to use all the "brainpower" it provides. However, Jammayrac said that it was actually easier to learn to fly than the AS332. Training takes about two weeks of ground school plus about 10 hours flight time, he said. A full transition from the AS332L2 to the EC225 would take "about four or five hours."

There was one other thing we accomplished in flying the EC225 off the coast of Marseille. Jammayrac flew me past the area where French divers had located the aircraft that Antoine de Saint Exupery was flying the night he disappeared during World War II. The disappearance of the famed author of "The Little Prince" had been a mystery for 60 years. But that's another story.

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