Pratt destroys blades in successful engine test
HARTFORD, Conn. -- In a concrete room at Pratt & Whitney's East Hartford plant, before an audience of federal regulators, a major customer and a corporate partner of the jet engine manufacturer, an explosion blew out an airplane engine blade.
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The episode would appear to be a major failure, even an embarrassment. Instead, it was a routine and successful test.
"Thank God it was anticlimactic," said Bob Saia, chief engineer at Pratt.
Pratt & Whitney, a subsidiary of
Saia compared it with cars built to be destroyed in crash tests.
The test of the GP7200 engine was intended to prove that what Saia called a "massive catastrophic failure" would not bring down the Airbus if such an event occurred in takeoff. The engine -- one of four on the double-decker jet that will carry up to 550 passengers -- shut down safely with no major rupture of oil or fuel lines that could cause a fire.
In addition, the mass of metal blown out by the explosive charge broke into smaller, contained pieces within the structure surrounding the engine and its blades. None punctured a wing, fuel tank or fuselage, Saia said.
The Airbus project is expected to generate several billion dollars in sales. The first engines are due to be delivered in 2006 to Emirates, the Dubai-based airline.
Passing the engine test, which is required by the Federal Aviation Administration, is a key step for Pratt, which must get through as many as 150 trials.
"It's one of the tougher tests you have to go through," Saia said. "It's a pretty dramatic event."
Other tests over 18 months include simulating extreme rain storms and blowing dead birds from an air cannon into a jet engine to represent a common airport problem: the proximity of gulls that get sucked into airplane engines.
About 30 full-engine tests, which include many more for components, include those for durability related to speed, temperature, vibration, and so-called ingestion tests involving birds, ice and rain, said Les Dorr, a spokesman for the FAA.
GE, Pratt's partner in the Engine Alliance that's building the Airbus engine, is conducting its own tests, said Deb Case, a spokeswoman for GE in Cincinnati. The engine will be tested by placing it on a
Pratt claims a strong track record in testing engines. The last time it flunked a test, requiring another try, was in the early 1980s, Saia said.
Pratt's test of the engine as it made 3,000 revolutions a minute was recorded by instruments and two dozen cameras, with the fastest taking photos at a rate of 10,000 frames a second. During the test, one of the engine's 116-inch diameter fan blades was blown out from the fan hub by an explosive charge as the engine ran at maximum speed equal to more than 82,000 pounds of thrust.
Completing the test didn't end the experiment. Pratt engineers spent a day picking up all metal pieces, including remnants of the fan blade, for an analysis of their condition and weight, Saia said.
The testing is expected to be completed by the end of the summer or early fall next year, and the engine should be certified for production in October 2005. Testing of engines and components is expected to become more stringent -- for fuel consumption, for example -- as airlines push the limits with longer-distance nonstop international flights, Saia said.
"If you want to sell products and be in this business you have to do it," he said.
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