Engine Alliance begins preparations following success of critical fan blade-out trials

The General Electric/Pratt & Whitney Engine Alliance GP7200 flight-test engine has been attached to General Electric's Boeing 747 flying testbed at Victorville, California and is to begin ground runs this week.

Preparations for the start of flight tests, which are expected to begin in early December, also follow the successful completion of critical fan blade-out tests that were performed at P&W's East Hartford site on 11 November. The blade was detached by an explosive charge while the engine was at maximum fan speed, equivalent to a thrust of more than 82,000lb (365kN).

 "We lost just the one blade and did very little damage to the others, while at the same time achieving containment and doing relatively little local damage to the acoustic liner," says recently installed Engine Alliance president Bruce Hughes. "It also continued turning for 10 or 11 seconds after the event, which is quite unusual. This rotor spun down, which says the loads were really within predictions."

 Meanwhile, the flight-test engine is expected to be taken through a short test phase to obtain initial engine operability data, while the main emphasis will be on gathering data for Airbus and the nacelle manufacturer Hurel-Hispano. This will include temperature and pressure information as well as "under-cowl" conditions. "We'd like to finish before Christmas, then drop the engine and bring it back. Then we'll fit the different compressor aerofoils and bring it back for a second flight-test phase," says Hughes.

 The second test phase, expected around April, will concentrate on engine performance and evaluations of the GP7200 with the production configuration high-pressure compressor. Unlike the earlier configuration, which will fly on initial tests, the production standard design has slightly altered aerodynamic and twist angle changes to the front three of the nine stages.

Performance shortfall and even surge issues were encountered on an earlier core test this year with the initial configuration, which suffered from "design and manufacturing process" problems, says Hughes.

 The reconfigured engine will also incorporate the improvements to the high-pressure turbine, which recently passed a core stress test after being redesigned to counter vibration problems experienced earlier this year (Flight International, 27 July-2 August).

 "We will do one more test in January to look at potential performance improvements in the turbine," says Hughes, who adds that the investigation will focus on reclaiming some of the blade trailing-edge area, which was pared back to eliminate the vibration. "That always affects performance, and maybe we did not have to cut back as much as we thought. We're going to move it back towards the line."

 Testing is due to be completed by the end of June 2005 and certification is set for the third quarter, with first flight on the A380 due in early November 2005. The first two GP7200s are due for delivery to Airbus at the end of June, with a second pair to complete the initial shipset due for delivery in late July.


Source: Flight International