Pumas et descendants

Flight Test: Eurocopter EC225 - Puma repowered
By
With the dual digital autopilot programmed to intercept the instrument landing system at Marseilles International airport at a 150° angle to the localiser and at high speed, my Eurocopter EC225 overshot the localiser once, slightly, and then captured it. It flew us down at 145kt (270km/h) as programmed, levelled us out at 80ft (25m) and continued down the centre line of the runway.

We could have programmed it to come to the hover. But instead, I pressed the "go around" button on the collective lever and off we went.

That is an illustration of the performance of the EC225. The medium-weight (11t), high-performance helicopter belonging to the Super Puma/Cougar family first flew in November 2000 and Flight International tested a prototype in February 2004. Since then, there have been several changes. While the basic Super Puma fuselage remains the same, the EC225 and its military version, the EC725, have resulted in a helicopter with considerable technological enhancements and much improved performance.



Patrick Penna
This Eurocopter EC225 is pictured flying over the Mediterranean, near Marseilles


More than 650 rotorcraft in this family have been sold and over 3 million hours flown. Sales of the EC225 are mostly to the civil market at a ratio of about 2:1. There are 122 aircraft in the fleet, plus 50 for the Brazilian military on order. Eurocopter listens to the operators and tries to satisfy all their requirements.

One of the biggest changes is the five-bladed main rotor, instead of the Puma's four. This enhances performance considerably. The blades are of composite materials and I noted the different shape, particularly at the tips. The Spheriflex composite rotor hub has no bearings to lubricate and maintain.

The helicopter's nearest competitor is the Sikorsky S-92, which Flight International also tested in January 2003.

Seating arrangements in the spacious cabin - although the cabin height is only 1.45m - vary from high-density 28 seats to a standard 19 crashworthy seats. There is an 8-12 seat VIP version, with toilet and cabin attendant, that has attracted the attention of several heads of state, says Eurocopter.

The 19 seats are offset to accommodate larger passengers more comfortably. They are attached to a reinforced floor and can be removed rapidly to convert the aircraft for freight. There are 15 tie-down points and provision for an on-board fuel tank.

The search and rescue configuration has a dry and wet cabin floor. So when you bring on board a casualty that has been pulled out of the sea, he/she is deposited initially on the "wet" floor to avoid spreading salt water over other sensitive areas. A typical example of Eurocopter's attention to detail.

SEARCH AND RESCUE

The aircraft I flew was configured for search and rescue, for which the EC225 is ideally suited with its high speed, powerful engines, excellent performance and long range. There is also an emergency medical services version.

Eurocopter has put a lot of thought and design features into the various configurations, so the aircraft has equipment, procedures and safety of the highest standard. For example, our test aircraft had a unique winchman station at the door. The winchman can fly the aircraft up to 20kt in any direction, with inputs monitored by the pilots. If the winchman overcontrols - and this was demonstrated on the flight by Christophe Skorlic, our flight engineer, by quickly stirring the winchman's cyclic control stick - the aircraft system damps down the actual aircraft movement.

There are many technical advancements on the EC225 compared with previous models of the Super Puma/Cougar family. These include modular design of mechanical components, the use of composite materials that offer strength with lower weight, modern avionics, an all-glass cockpit with large LCD multifunction displays, a vehicle monitoring system that can show the pilot everything needed about the aircraft systems, and an extremely competent automatic flight control system.



The pilot has more of a monitoring role than actually handling the aircraft, as I was to find out. The new-generation Turbomeca Makila 2A1 engines give lots of power with maximum safety due to the fully redundant dual full authority digital engine controls and a back-up system in the unlikely event of both FADECs failing.

If that happens the power on both engines will not freeze at the point of failure and should be adequate to take you back to base. An engine change takes about 30min, says Eurocopter. The aircraft can be equipped with a full de-icing system, including the tail rotor, with no icing restrictions.

With the optional extra cold weather kit, the aircraft can be operated in temperatures as low as -45°C (-49°F). This is a major step forward, although the Russians have been doing this for years for their operations in Siberia.

The helicopter is so well designed that it can be flown by a single pilot in visual meteorological conditions. Otherwise two pilots and, if necessary, a cabin attendant and/or flight engineer are required.

A maximum gross take-off weight of 11,000kg (5,000lb) and an empty weight of 5,280kg gives a payload of 5,720kg. This includes crew, fuel and passengers/freight. With full fuel at 2,017kg, this allows 3,712kg payload, more than enough. The external sling load maximum is 4,750kg. Sling work allows an additional 200kg on the 11,000kg MGTOW.

I asked my pilot, Jacques Larra, an experimental test pilot, to do a standard pilot pre-flight inspection. It was thorough, but quick. No climbing up steps to check levels and the like. He opened the rear tail boom baggage compartment. This is large enough to contain the bags of 19 passengers.

ENDURANCE

The sponsons are multipurpose and contain energy absorbing (self sealing) fuel tanks. There are fittings for quick fit external pod fuel tanks on both sides of the fuselage thus increasing the range and endurance even further. Because it is a SAR aircraft, there are a bunch of downward pointing lights on the aircraft belly to illuminate the area below, plus other lights to highlight the dual winches area. The main rotor blades can be folded.


The cockpit is user friendly. The attention to detail is such that Eurocopter has drawn a black line down the side of the fuselage under the pilot's door to show where the left leg goes on the way down to meet with the step.

There is plenty of room for pilots to stow their on-board equipment, although charts and plates are not required since the aircraft system contains everything a pilot needs to conduct a flight. The seats are comfortable with a full harness and even two armrests, a nice touch. The seat can be adjusted for height and reach, as can the pedals.

After a thorough cockpit familiarisation session from Larra, flight engineer Skorlic turned on the fuel valves and pumps and selected "start" on both engine switches. We sat back and watched. Each engine started in turn and took the rotor to flying speed.

The starts were cool and gentle. Larra pressed the "test all" button, which the systems did, and we were ready to go within 3min. This is a major achievement for such a sophisticated aircraft and ideal for search and rescue when you need to get going quickly.

Eurocopter's experience in pilot-helicopter interface technology and ergonomics is embodied in the display system. The predominant instrument panel display is the large, multifunction four 6 x 8in (150 x 200mm) LCDs that give the pilot all the knowledge about the flight that is needed - where the aircraft is in space in terms of airspeed, altitude, both baralt and radalt, attitude, rate of climb and descent, where the pilot wants to go and the limits of airspeed and engine power, how much power is being used, and, most importantly, how much more is available.



Even though I had not done the full training course, I was easily able to interpret the presentations. The LCDs can display whatever other information the crew requires - a full route display for example. In the unlikely event of a full display failure (as happened to us in the Tiger) there is a "get you home" single instrument hat shows main rotor pitch, airspeed and attitude and compass heading.

When in autopilot, just like a modern fixed-wing aircraft, the automatic flight control system will not allow exceedences of the flight envelope. Larra tried to exceed the VNE during our flight, but it would not let us. It also stopped us at 100ft when diving down to achieve the VNE of 175kt. This is excellent protection and shows the attention to detail to provide a safe vehicle.

This VNE is approved up to a density altitude of 5,000ft, which is remarkable for any helicopter considering the problems of retreating blade stall, reverse flow over the retreating blade and the compressibility effects on the tips of the advancing rotor blade - although the rotor speed is low at 275rpm compared with the 300rpm-plus of other helicopters.

The engines and their FADEC management system are impressive. They deliver enough power to be able to climb on one engine at MGTOW at 5,000ft at 400ft/min, a comforting thought for the pilots (and passengers). The transmission, which can often be a limiting factor with powerful engines, is also capable of accepting even more power than the engines provide, a refreshing change from older helicopter designs. FADEC always keeps the power within the gearbox limitations.

We came to the hover on the main runway at Marseilles International airport and I pressed the "go around" button on my cyclic stick. The aircraft flew us to our first waypoint at the speed and height that Larra had inserted. He deliberately took us over some high towers. The warning system declared loudly, several times "caution, obstacle! caution, obstacle!".



The primary LCD showed a horizontal white line which crossed through the indicated airspeed, attitude indicator, rate of climb and descent indicator, baralt and radalt. This indicated that all the parameters of flight were being observed, within limits and that we were in a stable flight condition.

We were light at only just over 9,000kg compared with a MGTOW of 11,000kg. We cruised at between 140kt and 145kt although by using maximum continuous power we could have cruised at 151kt. At maximum gross weight the EC225/725 will cruise at 141kt with a fuel burn of only about 670kg/h. This is fast for any helicopter and efficient in terms of fuel flow. The rate of climb on both engines at maximum gross weight is in excess of 1,000ft/min. Range with standard tanks is 830km (450nm) and with the extra internal tank 935km.

Endurance with standard fuel tanks is just over 4h and with the extra tanks more than 5h, a useful addition when on an SAR mission, for example. There is even more endurance with the on-board fuel tank, on a ferry flight for example.

I was able to change our pre-selected height and speed using the trim buttons on the cyclic stick and collective lever. In the high-speed cruise, Skorlic selected one engine inoperative training mode on the simple overhead engine management panel. This gave us all the sensations of a real engine failure but used only maximum continuous power on the good engine instead of the 30s emergency power in the event of a real failure. This is to protect the life of the engine.

The "failed" engine sat at ground idle, ready to come into action. I saw the rotor rpm droop from 100% to 95% then slowly recover to about 98%. The on-board system then started the countdown and, after 30s, I selected the next lower 2min power setting by pressing a button on my stick - and so on, to maximum continuous power. In the event of a real engine failure, all the pilot has to do is press a button when prompted.

Since this was a SAR equipped aircraft we did a simulated mission. The aircraft flew us to the search area and fully automatically set up a search pattern. There is a choice of patterns. The pattern came up on one of the LCDs. As the search progressed, I was invited to select the hover position as we flew over the "casualty" by pressing one button and selecting the hover height. The aircraft immediately left the search pattern and came to an offset hover near the supposed casualty and into wind.

The wind speed and direction was shown on the LCD and offset so that the winchman can see the person/s below and also to avoid exposing him/her to downwash. The helicopter can be programmed to follow automatically a moving target such as a boat.

While in the hover, our flight engineer gave us an engine failure. I pressed the "go around" button on the lever. The aircraft nose dropped, we lost a little height during the acceleration before we started to go uphill.

Larra selected the VNE of 175kt. There was little increase in vibration. Turns did not affect this. The aircraft dove down to achieve it. He tried to exceed 175kt, but the flight envelope protection system would not allow it. For certification purposes, the aircraft has to be taken to VNE + 10% with no adverse properties. The EC225 has been taken to 210kt with no adverse effects, says Eurocopter. A comforting result for the crew. As we neared the ground in the dive, the autopilot levelled us off at 150ft with an aural "warning, terrain! warning terrain!".


Skorlic failed the number one hydraulic system. Handling the aircraft was still easy, only the lever needed slightly more effort. Nothing else changed. All the automatic systems were then taken out and I flew the aircraft raw. The cyclic stick was a bit stiff and I suffered from some slight "pilot induced oscillations", which is a well-known event in such sophisticated aircraft, but I felt that, after some practice, I would be confident enough to fly on instruments and to carry out a precision landing, such as on to an offshore platform - or hand over control to the co-pilot.

I handed over control to Larra and invited him to demonstrate the aircraft's agility. There is no published limit on angle of bank (unlike another manufacturer's combat helicopter that I tested - 60°!) He carried out sustained 90° turns at high speed, pulling more than 2g. The warning system did not like this and called "bank angle! bank angle!"

During the subsequent manoeuvres, I felt the negative g as the nose was pushed hard over to the vertical. The stall turn/wing over, also from a vertical nose-up position, was graceful, with plenty of tail rotor control and finished with a vertical dive.

CONCLUSIONS

Eurocopter has put a lot of expertise into the design of the EC225. It is truly multi-role. Although it has complex systems, it is very user friendly. There is a lot of redundancy in the major systems and a lot of protection. It is just like a modern fixed-wing airliner, where the pilot programs the flight and then sits back and monitors it.

The automatics do not allow the flight envelope to be exceeded. The high speed, high power available and excellent performance is a major step forward in the helicopter world. The ratio of flight time to maintenance is variable. I got several interpretations, from less than 1h to 4h

Eurocopter’s Super Puma/Cougar/EC225 Family marks 4 Million Flight Hours

Eurocopter’s heavy-duty family of helicopters, the AS332 Super Puma/AS532 Cougar and their latest-generation derivatives, the EC225/EC725, have accumulated a total of four million flight hours in service. To date, 740 civil and military variants of this product family are in service with customers around the world, mostly serving in offshore oil and gas services in the harsh conditions of the North Sea, SAR (Search and Rescue) and VIP transport, as well as demanding military missions such as Combat SAR and troop transport in hostile environments.

Super Puma family helicopters are in operation in more than 20 countries from extremely low temperatures in Norway to extremely high temperatures in North Africa and in the toughest maritime environments. This unrivalled experience combined with proven technological concepts provides these helicopters with an unmatched warranty of success in life saving as well as oil and gas missions. The result is an operational availability of the Super Puma family that exceeds, on average, 98 percent.
...

nitial investigations into the 22 October ditching in the North Sea of a Eurocopter EC225 Super Puma show strong similarities to an earlier controlled ditching involving the same aircraft type in May this year, with the failure of a critical gearbox component again the trigger for the incident.

A special bulletin compiled by the UK's Air Accidents Investigation Branch says the aircraft, a 2007-built airframe (G-CHCN) operated by CHC Scotia, was put down 32nm (59km) southwest of Sumburgh in the Shetland Islands on a routine flight from Aberdeen with 17 passengers and two crew on board.

The bulletin says that the crew ditched the aircraft following a warning that the main gearbox lubrication system had failed. An attempt to operate the emergency system was met with a similar failure warning, it says.

The AAIB report notes that the 10 May incident, involving another EC225 (G-REDW), operated by Bond Offshore Helicopters, also featured the loss of the main gearbox lubrication system following a complete failure of the bevel gear vertical shaft and subsequent indications of failure in the back-up lubrication system.

However, the latest AAIB bulletin into the event, issued on 17 October, concluded that the emergency system had been operating correctly but had given a "false warning" of failure. It had mandated Eurocopter to review the design of the system to ensure the system provides correct information to pilots.

A preliminary examination of the main gearbox on G-CHCN, showed, as with G-REDW, a 360˚ circumferential crack on the bevel gear vertical shaft, says the AAIB. This meant the gears that operate the main oil pump were no longer being driven.

An EASA airworthiness directive (AD) issued following the May ditching issued monitoring requirements on helicopters fitted with bevel gear vertical shafts of a certain age or serial number. However, it notes: "The vertical shaft fitted to G-CHCN was not within the applicability of the AD."

In fact, two Vibration Health Monitoring sensors - on the bevel gear and the oil pump wheels - had both shown exceedences of alert thresholds in the two sectors flown immediately prior to the critical journey on the day of the accident, says the report. However, as the airframe fell outside of the AD, the operator was not required to download the data at that time.

EASA and Eurocopter are reviewing the requirements to widen the applicability of the AD, the AAIB says.

The three main operators of helicopters in the North Sea - CHC, Bond and Bristow - all grounded their EC225 and AS332L fleets following the incident. As of 25 October the flight restriction was still in place.

Eurocopter says: "The current investigation will allow us to better understand the exact circumstances surrounding the incident and to provide our customers with the necessary information and explanations that will enable a resumption of safe operations."

Returning the grounded EC225 fleets in Norway and the UK to unrestricted overwater flight status is Eurocopter's "highest priority", as the company grapples with a technical issue "more severe than anything in the past".
Lutz
Bertling, the airframer's chief executive, says he is confident the
type can be brought back into service by April, through the
implementation of "additional safety barriers". This is despite
Eurocopter being unable to identify the root cause of the cracks in a
component that caused two ditchings of the type in the North Sea in May
and October 2012.
The proposed interim solution outlined by
Bertling includes increased inspection intervals, tighter monitoring of
the EC225's vibration detection system - which can identify the
beginning and propagation of a crack - and potentially limiting the
power available in certain situations.
"We need to install these
additional safety barriers to convince the regulators that we can fly
safely," he says. "But even if [the regulators] say they will lift the
restriction, we need to convince the oil companies and the passengers
that it is safe to fly."
Bertling says talks are ongoing with the
safety regulators to get the restriction rescinded. Speaking in Paris on
23 January, he said he is confident this can be achieved by April, or
even March, "if everything runs perfectly".
In the meantime, bench and flight testing continues as Eurocopter strives to come up with a more permanent fix.
"Let's
not forget this design has more than four million flight hours, then it
failed twice. We need to be able to find the parameters that led to the
failure of this shaft," Bertling says.
Engineers have
artificially induced cracks into a number of test shafts to observe how
the fracture propagates. But, as Bertling observes, this is a lengthy
process. "We need hours and hours of testing to get to it, there is not a
one-shot catastrophic failure."
Bertling has also apologised for
the "very severe impact" the grounding has imposed on the oil and gas
sector, which is "one of the most important customer groups we have".

Eurocopter
has released further details of its planned fix for the problems
bedevilling the EC225, which led to an estimated two-thirds of the
global Super Puma fleet having being grounded since last October.
The
Marseille-based manufacturer released the information to its technical
publications website on 24 May, describing it as "proposed improved
safety measures and EC225 roadmap for the complete return to service".
It says the proposals - if accepted by EASA - should allow the 11t helicopter to "safely return to flight" in June or July.
The
effective grounding of the Super Puma fleet took place following two
North Sea ditchings in May and October last year caused by the failure
of the helicopter's main gearbox bevel gear vertical shaft.
Although
the airframer has proposed a number of short-term fixes to enable the
EC225 to fly again, it says further action will be required. "In the
longer term, all affected shafts in the EC225/EC725 fleet will be
replaced by new shafts. These new shafts will have a modified design to
eliminate any risk of crack initiation," it says.
Its
investigations have pinpointed the route cause of the cracking to three
factors, it says, listing corrosion, manufacturing stresses and "reduced
fatigue strength due to stress 'hot spots'".
It proposes a
two-step approach - still to be certificated by EASA - of modifying the
area around the shaft and updating its maintenance regime to reduce the
possibility of corrosion occurring, allied to a regime of increased
monitoring. This replaces eddy-current inspections with ultrasonic
inspections, it says, and will allow operators to fly for around eight
to 10 hours between checks.
Additionally, Eurocopter plans to
install a system in the aircraft to enable in-flight detection of the
presence of a crack, with an amber warning light in the cockpit to alert
pilots.
"Although subject to approval by the authorities, we
anticipate that a flight time of two hours will be allowed following the
initiation of an in-flight warning," it says.
The new procedures
are expected to be introduced early this month, with training commencing
on 10 June. Certification of the in-flight warning system is
additionally anticipated for early June, it says, with modification of
the fleet following.
Meanwhile, Eurocopter expects approval of the
modified shaft in 2014, with retrofits available from the third
quarter. "All newly delivered aircraft will be fitted with the new
shaft," it says.

The European Aviation Safety Agency (EASA) published today an Airworthiness Directive which approves and mandates the technical solution proposed by Eurocopter for its EC225 fleet. The objective is to fix the unsafe condition created by the shaft failure of two EC225 helicopters in the North Sea in 2012.

The Eurocopter solution comprises of a set of modifications and inspections which aim at monitoring and detecting vertical shaft crack conditions and reducing the likelihood of any shaft crack initiation. When complied with, this solution ensures safe and airworthy operations of the EC225 type.

EASA will continue to work closely with Eurocopter, with the relevant National Aviation Authorities and the accident investigators to ensure that the fleet is operated safely, and may update its directive based on further investigation results.

Details on the EC225e were outlined at the 2014 Heli-Expo convention in Anaheim, California, along with the first orders.

The twin-engine EC225e has improved capabilities that include more payload, an additional fuel tank for very long range flights, a new cabin layout for improved passenger comfort and new avionics to significantly increase pilots’ situational awareness while reducing workload.

Certification of the EC225e is targeted for late 2015, followed by the delivery start-up in mid-2016.

“We developed the EC225e to meet growing requirements for longer-range flights, while retaining top levels of performance, passenger comfort and operational safety,” explained Airbus Helicopters President Guillaume Faury. “This is particularly valuable for oil and gas missions as the exploration and recovery of energy resources moves further offshore and into deeper waters.”

The EC225e will be powered by new Turbomeca Makila 2B turboshaft engines for improved performance, providing 550 kg additional payload. Such gain will provide a radius-of-action extended by 50 nautical miles with 19 passengers or 10 passengers up to 300 Nm with a new fuel tank. These powerplants incorporate a new combustion chamber and blades in the high-pressure turbine, enabling the EC225e to take off at its maximum all-up weight in CAT A conditions.

A new seating layout, which was designed in coordination with customers, provides increased comfort for passengers and offers better access.

In the EC225e’s cockpit, the equipment lineup includes a Euronav7 moving map system, automatic identification system (AIS), TCAS2 collision avoidance system, and flight management system. Among the helicopter’s enhanced operational capabilities will be the capability to perform automatic GPS (global positioning system) approaches to oil rigs or airfields that are not equipped with radio navigation means.

In the cockpit, the optional Rig’N Fly GPS-navigation-assisted software program aims to make oil rig approaches safer, thanks to a reduction in pilot workload. The system, which is retrofittable, has just been EASA certified.

The helicopter's mtow is being increased from 24,229 pounds to 24,581 pounds, allowing an operator to carry an additional fuel tank. As a result, the radius of action can be pushed to 300 nm with 10 passengers.

Investigations are continuing, he says, as the “root cause is still not clearly identified”.

However, he says the company is making “good progress” with EASA towards understanding how soon the H225 and AS332 L2 fleets might be returned to flight.