The second of two upgraded Pratt & Whitney PW4098 turbofans was expected to be delivered to Boeing by late June, to allow flight tests of the 777-300 to resume in July, following a two-month delay caused by the discovery of cracked compressor stators in April.
The powerplant was originally due to be cleared for 777-300 operations in late June, with first deliveries to Korean Air Lines expected to begin in September. Following the crack problem, however, the first delivery has been pushed back by almost three months, to December.
The first part of the test programme involved a PW4090 on one wing and a 436kN (98,000lb)-thrust PW4098 on the other. In the delayed second phase, which is scheduled to re-start on about 21 July, test aircraft WB551 will be fitted with two PW4098s. The revised design incorporates forged compressor stators in place of the original cast parts.
The delivery of the engine coincides with the re-running of some major powerplant tests. These include maximum exhaust gas temperature, low pressure rotor, high pressure rotor and150h endurance, as well as large-bird ingestion tests.
WB551 is the last remaining 777-300 test aircraft in the programme. All of the remainder are now either in storage awaiting refurbishment, or actually undergoing refurbishment.
WB501, the first Rolls-Royce Trent-powered -300 is due to be delivered to Cathay Pacific Airways in October, while WB503 was expected to be handed over to the Hong Kong carrier by the end of June. WB502 is slated for delivery in September.
The first PW4090-powered 777-300, meanwhile, WB531, is in long term storage before beginning refurbishment in September for delivery to All Nippon Airways (ANA) in April 1999.
ANA is also expected to receive two more 777-300s, in August and September 1998.
Source: Flight International
