Saturday, March 1, 2008
Aircraft Operations: Taking the EC145 to New Heights
Over 50 years after it was founded in 1954, the air wing of France’s Gendarmerie Nationale – a national police force belonging to the Defense Ministry and primarily tasked with policing outside cities and large towns – is partway through an ambitious renewal of its helicopter force.
That gradual process by 2013 would see the Groupement des Formations Aériennes de la Gendarmerie Nationale operating a fleet consisting only of twin-engine helicopters certified for single-pilot IFR. The air group has to date taken delivery of eight Eurocopter EC145s out of 15 on order. These are gradually replacing the old but much-loved Artouste-engine Alouette 3s, the last four of which is to be retired this year. In addition, a planned 37 EC135s will replace the 32 single-engine AS350B/B1/B4 Ecureuils (AStar). A first batch of 12 has been ordered, with an option for 25 more, for 233 million euros.
Whereas the EC145 primarily would be used for mountain rescue missions in the Alps and Pyrenées mountains, as well as in some of France’s overseas territories, the EC135s would be used in the rest of the country for the Gendarmerie’s conventional police missions, where hot-and-high performance is not as much of a requirement.
The Gendarmerie made a conscious decision to opt for two different aircraft types, rather than an all-EC145 fleet (as acquired by the Sécurité Civile, a separate organization that is part of the interior ministry and provides helicopter support to the French government’s civil agencies). The reason is that, being responsible for mountain rescue and some key police missions, the Gendarmerie could not afford to risk that its entire fleet be grounded for technical reasons, for example, during air accident investigations or for technical causes.
This outweighed the added cost of operating two different types, and was shown to be a smart decision when the Sécurité Civile’s EC145s were grounded twice, after two helicopters crashed in 2003 and 2006. The Gendarmerie’s EC145s continued flying, albeit with some restrictions.
Those accidents brought to light some issues specific to the EC145 and mountain flying that had not been previously identified, despite the aircraft’s long career. Those issues required remedial action. Although marketed by Eurocopter under its new designation since 1999, the EC145 is, in fact, an upgraded BK117 (the C2 version). As such, it has been around for quite some time.
"We tend to fly at higher altitudes than most," said Lt. Col. Marc-François Duclos, the air group’s flight testing chief, "so we ran into performance issues that others had not faced before."
The EC145 has the advantage of a rigid main-rotor hub, which some experienced mountain pilots find provides more control authority and better response to pilot control inputs.
The Gendarmerie did request minor changes to the instrument panel. The Mast Moment Indicator, originally composed of two adjacent bar graphs (one for each axis) will be replaced by two concentric circles, making it much easier for the pilot to monitor.
The tail-rotor controls were also modified. A badly finished cable ring in the control run tended to give pilots the false impression they had reached maximum pedal travel. This was fixed by replacing the ring with a Teflon-coated one. Also, a rudder-control switch was fitted from the Super Puma. The rudder pedals were also made more sensitive.
In addition, a rescue hoist with a longer cable was fitted to the aircraft.
The most significant issue, however, concerns the EC145’s tail-rotor authority and power margin at high altitudes. The aircraft is vulnerable to crosswinds, and doesn’t much like tail winds. Although certified for crosswinds up to 17 kt, it still requires particular attention, especially at higher altitudes.
The Gendarmerie found it necessary to modify its procedures for high-altitude operations to work around the tail-rotor authority issue. Mostly, this consists of alerting pilots to the machine’s quirks, and preparing for remedial maneuvers in case they are needed. For example, pilots were initially free to fit the rescue hoist on either side of the cabin. Placement is now limited to the starboard side. This is not only for visibility reasons. With the starboard side to a mountain face, the pilots can quickly and easily fly away using the tail rotor in case of a problem.
"We know that torque can push it off to starboard, but now we know better than to get into such a situation," said Col. Jean-Thierry Daumont, the air group’s commanding officer and prime mover behind the force’s modernization.
With the EC145, Gendarmerie pilots also had to get accustomed to a bigger aircraft, and a twin-engine one. The EC145, for example, generates a much stronger downwash than its predecessors. This can raise snow flurries and can blow people off balance, in both cases creating potentially tricky situations during mountain rescues. The aircraft also requires attention to how the cargo and passengers are distributed within the cabin, which was obviously never an issue in the much smaller Alouettes or Ecureuils.
None of these issues proved critical or insurmountable because of the gradual and pragmatic way the air group went about evaluating the aircraft when it first entered service. It also benefited from the lessons learned from the two Sécurité Civile crashes. With adequate procedures, said Daumont, the EC145 is a very good aircraft. He adds that, during their annual performance/assignment reviews, Gendarmerie pilots say their main wish is to keep flying the EC145, even if this means losing out on a more attractive posting flying Ecureuils.
"In fact, they’re now more interested in that than which station they’ll be posted to, which is pretty much a new phenomenon for us," he noted.
It also helps that the Gendarmerie trains its own pilots, so their experience is similar. Pilots are only posted to mountain stations, flying the EC145, after logging a minimum of 1,000 flight hours and taking a special mountain course of 80-100 hr, most of them in Ecureuils but with at least 20 hr on the EC145. Mountain pilots are checked out at least once a year.
Gendarmerie pilots like the EC145 because it is large, comfortable and easy to fly.
"You can fly across France on autopilot, without touching the controls," said Duclos, and once the necessary procedures are followed, it performs superbly at high altitudes. "It’s almost overpowered when hovering into a nose wind, very stable with low vibrations, and has a very good payload-to-power ratio."
Finally, it’s a very fast climber, and "its climb speed goes off the charts when flying into the wind."
Gendarmerie pilots wax lyrical when talking about mountain flying.
"The mountain speaks to us through the aircraft, and the aircraft speaks to us through the controls," said Duclos. "So much so, in fact, that pilots tend to switch off the autopilot at altitudes and fly manually to make sure they get as much feedback as possible through the controls."
Obviously, the EC145’s size means it is much more flexible than the Alouette 3s it replaces. That’s true not only in terms of payload (up to eight passengers, or two stretchers with medical attendants and a full equipment suite) but also of cabin volume, which is triple that of the Alouette.
The increased capabilities are also due to the mission equipment package. In addition to the Eurocopter/Thales Avionique Nouvelle avionics suite, which it shares with the smaller EC135, the EC145 carries a more powerful rescue hoist with a 90-m (295-ft) cable and 270-kg (595-lb) capacity. It also has a Wescam MX-15 sensor ball fitted with two daylight TV cameras and a thermal imaging camera, which automatically focuses the image, assists in tracking objects on the ground and permits live-image downlink. The mission kit also includes a Spectrolab SX-16 Nightsun with an infrared filter, loudspeakers, and night-vision goggle-compatible flight deck.
The Gendarmerie is also very happy with its mission availability rate of about 90 percent — "and that’s per aircraft, not a fleet average," stressed Daumont.
One reason is that the Gendarmerie flight engineers are also ground engineers, and thus look after the aircraft they fly on. Incidentally, these engineers are also called upon to operate the rescue hoist, the sun light, and electro-optical sensors, and to serve as loadmaster. A second pilot is only used when flying with night-vision goggles.
The air group operates 26 permanent and two summer bases spread throughout metropolitan France, and another five in its overseas territories. Metropolitan bases are located at civil airfields or military bases, selected so that each one covers a radius of about 20-25 min flying time, with as little overlap as possible. The EC145 is deployed in the mountains, at Villacoublay, the French air force VIP base near Paris that also hosts the air group’s headquarters, and in French Guiana, where the EC145 was to replace an Alouette 3 in December. Other bases operate Ecureuils.
The air group has a force of 410 personnel, including 134 pilots (one-third officers, two-thirds NCOs), 170 maintenance personnel, and 72 support staff who carry out vital work supporting the operations bases (which normally only consist of six people: two pilots, three engineers and a support staffer). An interesting point is that all Gendarmerie crews are qualified as "judiciary police officers," which gives them added legal and investigative power. That can help on mountain rescues, where foul play is found more often than one would suspect.
Despite deploying in such small units, the group’s helicopters fly a fleet average of 180 hr a year, rising to 230-250 hr for mountain and some overseas bases. In 2006, for example, the EC145 stationed at Chamonix, near Mont Blanc, logged 525 flight hours. Each unit carries out its own first-echelon maintenance. Intermediate maintenance is done at the group’s technical base at Le Blanc, in central France. Eurocopter carries out all depot-level and heavier work.
Overall, the air group logged 16,500 flight hours in 2006, carrying out 11,167 missions and rescuing 4,045 people. The bulk of the missions (45 percent) were conventional police work (criminal investigations, public order, surveillance, etc.), while 18 percent involved rescue, 15 percent training, 14 percent searches for missing people, and 3 percent maintenance checkouts.