Guy Norris/LOS ANGELES Paul Lewis/SEATTLE
Pratt & Whitney estimates that corrections to cure cracked compressor stators in the PW4098 discovered in April will push deliveries of the first heavyweight Boeing 777-300 to Korean Air (KAL) back by almost three months, to December.
"It's a cast part, and we've opted to change that to a forged part," says P&W senior vice-president, programmes and service, Bob Leduc. The change in fabrication technique means that some critical certification tests completed earlier this year will have to be repeated. "Certification should be at the end of July and delivery to Korean will be in early December, or roughly two and a half months late," says Leduc.
Boeing confirms that deliveries to (KAL) has been delayed until at least December, and industry officials are warning that redesigning the engine's compressor stator and completion of certification could delay deliveries until early 1999. Boeing says that certification of the lower thrust PW4090-powered 777-300 is on target for June, and the first aircraft is scheduled for delivery the same month to All Nippon Airways, with deliveries to Japan Airlines beginning in July.
The major tests to be re-run include the maximum exhaust gas temperature (EGT), N1 (low pressure rotor), N2 (high pressure rotor) 150h endurance test, and large bird (1.5kg) ingestion tests. "These should be run in late June and early July," he adds.
Leduc says P&W "was surprised" by the cracking event uncovered during testbed runs and adds that the major certification tests are being run "-because this 777 will be certificated for 180min ETOPS [extended range twin operations] from day one".
Source: Flight International
