A380 engines

After a thorough evaluation process, Qantas announced on February 16 2001 that it had chosen the Rolls-Royce Trent 900 over the competing Engine Alliance GP7200 to power the 12 A380s it had on order. It has since also chosen the same engine for its additional eight aircraft it ordered in 2006.

“Both engines are leading edge,” Qantas EGM engineering and maintenance David Cox explained to Australian Aviation.

“There was very little to discriminate between them and commercial considerations were certainly a factor. The Trent 900 offered slightly greater operational efficiency and is a scaled and improved design derived from the Trent family of engines that were already proven in service on other aircraft types. They therefore provided a lower overall risk profile with equivalent economics. ” This experience Rolls-Royce has had with earlier Trents, which power a number of Airbus A330s and A340-500s/600s and Boeing 777s, has made it the engine of choice for most A380 customers. To date, 10 of the 13 A380 customers who have made an engine selection have chosen the Trent 900 over the GP7200, including Singapore Airlines, which was the first customer to put the A380 into commercial service in October 2007 (although the A380’s biggest customer, Emirates, has ordered the GP7200 for its fleet).

“The Trent 900 offers the highest level of maturity on the A380, with over 22,000 engine test flying hours, five times more maturity than any other engine on the A380,” said Rolls-Royce spokesman Neil Williams. “This maturity level is key to providing high reliability and excellence in operation. ” The Trent 900’s development started in 1996, with RR first launching the engine in September that year. At the time, it was conceived as a powerplant for Airbus’s proposed A3XX (which became the A380) and a competing stretch of the Boeing 747, although work on the jet slowed during the late 1990s until the A380 was officially launched in 2001.

This saw further work on the engine progress through the early 2000s, with the Trent 900 first running, on schedule, in March 2003, followed by its maiden flight, on an Airbus A340-500 flying testbed, in May 2004. Engine certification was achieved on schedule in October 2004, ahead of first flight on the A380 in April 2005.

The Trent 900 is also one of the few civil jet engines to have proven its ability to run on alternative fuels, with a Trent 900 powered A380 conducting a flight powered by gas-to-liquid fuel in February 2007.

The Trent 900 is certified to produce up to 80,000lb (358kN) of thrust, although on the A380-800 it will only produce 70,000lb (311kN), which is controlled through the engine’s FADEC (full authority digital electronic control) system.

The Trent 900 features a 2. 95m diameter fan which pulls over 1. 27 tonnes of airencased in a new titanium casing, which weighs less than other Kevlar fan casings yet is still strong enough to contain a fan blade failure, as was demonstrated during the engine’s testing in 2004.

It is also the first RR commercial engine to feature swept fan blades, which allows the fan to run at an optimal speed and reduce noise. The fan blades themselves are made of hollow titanium, which helps to reduce the engine’s weight while maintaining their structural integrity.

The Trent 900 series is also the first large civil engine to feature a counter-rotating high pressure shaft. This technology, which has long been used on the Panavia Tornado’s RB199 and the Harrier’s Pegasus engine, allows air passing through the IP nozzle guide vanes to travel on a straighter path. This improves the performance of the IP turbine, and results in fewer and lighter parts and therefore reduced fuel burn.

The Trent 900’s tiled combustor chamber also runs at a much hotter temperature than previous engines, such as the RB211 which powers most of the Qantas Boeing 747-400 fleet. This allows the engine to produce much more thrust at lower rates of fuel consumption.

The Trent 900 also features an engine health monitoring (EHM) system, which continuously monitors and collects data on the engine’s health and performance, which will aid in maintenance of the engines.

“The Trent 900 EHM also allows us to detect minor issues which would previously only have been detectable through borescope inspection. With the latest available filter technologies, servicing intervals are also not as frequent,” said Cox.

Maintenance has also been made easier as the accessories for the Trent 900 are mounted on the engine’s fan case. This puts most of the sensitive equipment away from the hotter areas around the engine and also makes access for maintenance much easier.

The Trent 900 has been designed to allow it to fit into the fuselage of a Boeing 747 freighter without the need to dissemble it, unlike the larger GP7200. This cuts down the handling time for an engine to be replaced at an out-station if required.

The combination of new technology and scaled components from earlier Trents has delivered impressive fuel consumption and environmental benefits for the A380.

“It has the lowest overall emissions of any engine available for the A380 and generates 2. 5 times less CO2 per passenger kilometre than an average family car,” said Cox.

According to Williams, “The Trent 900 has over 260 per cent of combined margin to CAEP6 regulations, the greatest margin on the A380. It also offers the lowest NOx [nitrous oxide] emissions, using only 74. 7 per cent of the CAEP6 limit. ” Cox also noted that the engine will allow Qantas to surpass current benchmarks on aircraft noise, which was of particular interest to the carrier due to its many flights to noise sensitive airports such as Sydney and London Heathrow.

“Testing by Airservices Australia has shown the A380 to be between 2. 3 and 6. 7 decibels quieter than a 747-400 during takeoff, and around 2. 1-3. 7 decibels quieter during landing,” he said.

As part of the Trent family, some technology elements included in the 900 have also been incorporated into the Trent 1000 which is one of the engine options on the Boeing 787, and the Trent XWB for the Airbus A350 XWB family. The XWB will feature the same swept fan blades as the 900, as well as the contra-rotating high pressure shaft.

The Good Oil

As the Trent 900 delivers a great many advantages from its new engine technology which has different needs compared to older generation engines, Qantas has selected a new lubricant for its new engines.

“The fuel efficiency benefits offered by the Trent 900 mean higher engine temperatures and the need for a new generation of synthetic turbine oil,” said Cox.

To that end, Qantas has committed to using BP’s Turbo Oil 2197 on the A380’s Trent 900s and also on the General Electric GEnx engines which will power the Qantas/Jetstar Boeing 787 fleet.

Compared to older generation Type II lubricants which have been used on most jet aircraft since the 1960s, BPTO 2197 is more robust and therefore suited to modern engines, such as the Trent 900.

“The increased temperatures seen in these latter generation engines has resulted in turbine oils that have historically provide good performance being stressed beyond their original design capability,” Air BP Lubricants technical sales manager David Fettel told Australian Aviation.

“BPTO 2197 provides significant improvements in oxidative and thermal stability which delivers unsurpassed high temperature cleanliness and resistance to coking in oil transfer tubes and bearing compartments,” said Fettel. “Coking in these hot oil wetted areas results in additional maintenance burden which has become common in later generation engines using the older STD class oils. ” On the whole, the Trent 900’s new engine technologies and the new lubricant which will be used for it should ensure that Qantas is able to operate one of the most efficient and easy to maintain A380 fleets in the world.

“The Trent 900 offered slightly greater operational efficiency. ”