Pratt & Whitney has resumed testing its PW6000 after the initial test engine was removed from the rig to replace a non-conforming component that threatened to result in high-pressure turbine (HPT) blade rub.

The engine's turbine on board injection system (TOBI), which feeds cooling bleed air from the compressor to the HPT, was discovered to be a 20,000th of a radius out. "This limited our ability to rapidly accelerate and decelerate without worrying about rotor rub," says PW 6000 programme manager Peter Smith.

PW claims the TOBI was found to be a tight fit when the HPT was installed and that it had always planned to rectify the problem during a scheduled removal from the test rig in early August for other test engines. Before this, rig testing was confined to the start-up programme, during which it remained at stabilised idle and did not exceed 4-5,000lb thrust (18-22kN). No evidence of rubbing was subsequently found.

The PW6000 will resume a month-long series of sea level performance tests during which strain gauges will be attached to the fan. Next month the engine will be moved to the Wilgoos altitude test stand. Pressure testing is to be completed by early November.

The engine will be joined by two more developmental powerplants which will focus on stress and strain testing and endurance testing, respectively. The PW6000, under development for the Airbus A318, is to be certificated by mid-2001.

Source: Flight International