Two new helicopter types have gone into service in the demanding North Sea environment this year: one an upgrade, one all-new. How have they fared?
The first day of September saw the first revenue flight of a Eurocopter EC225 with UK North Sea operator Bristow Helicopters. Earlier this year, Sikorsky’s new S-92 also started earning its keep with two other operators – one a sister company to Bristow – serving the Norwegian sector. It is too early to tell whether the two EC225s have smoothly integrated into the Bristow fleet but, as an upgrade to the tried and tested AS322L Super Puma, the odds are in its favour. However, with six months’ service behind it, the all-new S-92 has experienced its share of teething troubles.
|
|---|
Bristow European operations director Willie Toner says the EC225s will replace AS332Ls in its North Sea fleet, with the older helicopters to be sent abroad. “We are offering them to customers who will find their increased payload and range attractive. These two aren’t committed to long-term clients yet, although they are both now earning revenue. We have two confirmed orders from Shell, which triggered the whole process, but will not take delivery of those until later next year.
“Normally we would stipulate the type as part of a specific contract bid and, to give you an idea of the lead times involved, we are currently tendering for a contract with a 2007 start-up. This gives us an opportunity to include new technology, such as the EC225, with the benefit of hands-on experience.”
The main selling point for any customer will always be safety, says Toner. European JAR 29 and US FAR 29 certification “is constantly evolving and requirements become ever more stringent, while range, payload and cost factors improve much more slowly”, he adds. ”The Super Puma’s features relate to a version of those standards that could be 25 years old.”
Increased weight
Chief pilot Nick Norman says the Super Puma Mk2 was a product of 1990s technology, “but the EC225 is very much a 21st century helicopter, and the type has come a long way”. He adds: “It has a massive increase in gross weight. The Mk2 increased the Super Puma’s weight from 8.6t to 9.3t while the 225 takes it up to 11t. It’s the first aircraft I’ve seen where you can put in full fuel and full passenger load and still not reach maximum gross weight.”
Bristow chose the 225 for a number of reasons, says Toner – notably the payload and a smoother and quieter ride for the passengers. “The fact that Shell went for it too had a bearing on the decision. Our specification included large windows, unique to Bristow, which are partly to make the cabin a more pleasant flying experience for passengers and partly to aid escape in an emergency. Two are also fitted within sliding doors on either side, which are jettisonable. They make a big difference to the feeling of space in the cabin. We now have a strengthened floor and crashworthy seats in the cabin – customers are starting to demand these.”
Minor modifications were made to the two aircraft – installing wing-mirrors, document stowage and first-aid kits – before they entered revenue service. The passenger entry step was widened also.
Training for air and ground crew is complete. Bristow qualified four training captains in France, who then started working with line pilots. It took about a month to bring enough aircrew up to speed for the two helicopters. Twenty Bristow engineers also underwent factory training on the type. Because there are no great technical differences between the AS332L and the EC225, this was a relatively painless procedure.
Serviceability has generally been good, says Norman. “We have had a few minor leaks from the main rotor gearbox seals – similar to a problem we had while introducing the 332L. We shall find a fix for it. The customers we have been flying for seem to like the 225 – 19 passengers under any conditions makes life a lot easier.”
Introducing an upgraded model of an existing helicopter should pose relatively few problems for manufacturer, operator or customer. But bringing in a completely new type requires a leap of faith by the latter two parties, and operators of the four S-92s plying the North Sea have had to deal with serviceability issues.
Bristow’s sister company Norsk Helikopter has had two S-92As in service for Statoil since April. Its competitor in the Norwegian sector, CHC Helikopter Service, has been flying two for Norsk Hydro since May. Both introduced operating limitations soon after revenue flying began, after one of the Norsk aircraft had a swashplate replaced by Sikorsky when a pitch-link attachment bolt lost torque and internal bushing wear was detected. In March, a Norsk crew put out a mayday call after experiencing a major drop in main rotor gearbox oil pressure while approaching an oil platform. The pilots carried out an uneventful landing on the rig.
The cause of the pressure drop turned out to be the failure of non-metallic vespel splines on the drive of one of the two externally mounted gearbox oil pumps. But the oil remained inside the gearbox housing. “As a result, a 50-hour inspection [of the oil pumps] was implemented,” says Norsk commercial director Geir Tynning. Sikorsky major accounts manager Jack Donahue says the manufacturer has developed a fix for this problem that will be in place “within the next month or so”.
The problem has been the bond between the non-metallic splines and the metal core connecting them to the rest of the pump. Donahue says: “It appears that the metal has slightly too smooth a texture for full bonding in some cases. It has proved difficult to chase this one down. Some pumps have worn significantly, but others have experienced very little wear. In the meantime, we have found a way of inspecting the pumps without having to remove them.”
Passenger comfort
Tynning says both S-92s are still flying for up to 8h a day. “Feedback on the type from customers and passengers is extremely good, particularly the passenger comfort and reduced travel time.” Since they were introduced, the two helicopters have carried more than 20,000 passengers and accumulated 1,000 flight hours.
Norsk plans to add three more S-92s to its fleet in 2006. Two will provide offshore services for ConocoPhillips between Sola and Ekofisk, and the third will fly between Sola and the Valhall, Ula, Gyda and Petrojarl Varg fields for BP and Talisman. “The new S-92s will each fly 2,500 hours a year,” says managing director Ivar Eie.
Vibration experienced on board one of its S-92s at high speed and weight troubled CHC Helikopter Service enough to instruct its pilots in May to reduce torque to as little as 65% and cruise speeds to 125kt (230km/h) compared with the maximum of 151kt. Managing director Keith Mullett says: “The vibration is within acceptable limits, but we decided to issue the guidance as a conservative measure until we feel comfortable with the adjustments we are making under Sikorsky’s guidance.”
The manufacturer will soon introduce a planned software upgrade to the active vibration control system and tune the bifilars (vibration balance weights) on the rotor head. “One way or another, I am very confident we will bring the vibration back to a more comfortable level,” says Mullett. “We can afford to take this conservative approach because our customer has been utilising the S-92 over relatively short sectors, so there is little penalty. Norsk Hydro understands exactly where we are and is very pleased with the performance of both aircraft.”
Mullett also says reports of excessive cockpit noise from avionics cooling fans “are not a major problem so far. Again we are working on that with Sikorsky, but I have not had any significant pilot feedback on this issue.” The manufacturer is also looking to beef up the support cables for the passenger door, which oil workers use as an unofficial handrail.
Donahue acknowledges Sikorsky has work to do to correct these faults, but points out that none of them has affected the service that operators provide to their customers. “The oil companies are very pleased with the aircraft,” he says. Certainly, sales continue within the sector: as well as the three subsequent orders from Norsk Helikopter, CHC Helikopter Service is to introduce a third S-92 into service with Statoil. Three more have also been ordered by Brunei Shell Petroleum.
Bristow’s European head of engineering, John Cloggie, has some sympathy with any operator that introduces a brand new type into service. “Inspections are more rigorous as you must expect problems to arise during the first few months. We don’t yet know how smoothly the EC225’s transition will be and remain vigilant in our maintenance philosophy.”
ANDREW HEALEY/LONDON
Source: Flight International
