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High score

The Engine Alliance, the 50/50 joint venture between GE Aviation and Pratt & Whitney, has just celebrated its 20th anniversary. Ian Harbison reviews the latest developments on the GP7200 engine

The GP7200 engine is in a comfortable place, says Dean Athans, President of Engine Alliance. In service on 117 Airbus A380 aircraft with Air France, Emirates, Etihad Airways, Korean Air and Qatar Airways, it is performing well and has a 60% share of the engines in service. However, there are a few clouds on the horizon.


While he agrees with the Airbus market forecast that there will be an inevitable need for the aircraft on routes between mega-cities with congested and slot constrained airports, the question is when will the orders arrive? He sees a number of reasons for the delay. Some airlines are risk averse, wary of economic changes or with an off season when they are unable to fill such a large aircraft; others may have greater passenger demand than their current fleet can handle but do not want to make the jump to a bigger aircraft. Looking at the current order book, the engine will eventually lose its dominant position with the Rolls-Royce Trent 900 overtaking it to grab 52% of the eventual market. In the meantime, the A380 production rate in Toulouse is slowly ticking down to eke out the backlog.


As a result, the key word at the Engine Alliance is incremental. There will be no major product improvement programmes, he says, and, if there is an A380neo, it will be too early in the GP7200’s lifecycle to develop a new centreline engine.


One of those incremental programmes was to address the overheating problems in the High Pressure Turbine (HPT) stage-2 nozzle module experienced a few years ago by Middle East operators. This included 2,600 engine cycles on the test rig, running beyond the normal limits to represent 3,500 cycles. Heated air and dust particles of the size actually found in operational conditions were blown into the engine during the tests, as blocking of the cooling nozzles was part of the problem. The modified HPT design was frozen in October 2013, with the successful introduction of new hardware to production on schedule in June 2014. Retrofits were carried out at quick-turn repair lines or at normal shop visits. He says Emirates and Etihad have both reported improvements and the shop visit limit in the Middle East is now at an average of 3,500 flight cycles.


As an aside, the test engine was torn down and photographed from every angle to produce a virtual reality presentation. By October, this will be made available to customers, who will be able to study the state of components at a very detailed level, alongside a briefing by an Engine Alliance engineer. 


Other minor improvements include a more efficient airfoil design in the compressor along with optimised clearances and active cooling of the HPT case during climb. The latter is a software change on the flight deck that provides a 10 to 12°C decrease and a small reduction in fuel burn.


On fuel burn, he says many of the improvements bring about fractional decreases that are noticed in the test cell but there are no plans for a deliberate product improvement programme to achieve a target level. If these small changes eventually accumulate to the level where collectively, they are meaningful, the company will go back to Airbus to have this officially approved. Of greater importance is to give airlines the ability to carry payload for a greater distance – the revenue value of 10 to 15 extra seats is five times greater than cost savings in jet fuel – especially on very long routes such as Hong Kong to New York or Dubai to Los Angeles. 


As for the operational benefits of these changes, dispatch reliability across the fleet is running at 99.93%, while Qatar Airways, which started operations with the engine in October 2014, is reporting 99.98% and Etihad, an operator since January 2015, has a 100% record. >>

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