Aviation Partners Boeing (APB) will begin flight tests of a winglet-equipped Boeing 737 Classic next month with supplemental type certification (STC) expected around mid-January.
The first flight of the winglet equipped aircraft, an ex-TAP Air Portugal 737-300 leased through UK-based Aircraft Leasing and Management, will take place in mid-November. The composite blended winglets are 2.1m (7ft) tall, slightly shorter than those on the Next Generation 737, and weigh around 66kg (145lb) each. "We expect to produce a 6.5% drag reduction," says Aviation Partners vice-president of programmes Jay Inman.
The drag reduction equates to a 5% block fuel reduction on a 2,780km (1,500nm) sector. Other expected improvements, including enhanced field performance, higher operating weight capability and better time-to-climb, will be assessed during flight tests. A winglet STC effort for the 737-400 is due to start early next year, with certification scheduled for June and retrofits offered from the third quarter.
Meanwhile, the joint venture has realigned its 747 winglet design study on the -400 variant. The company hopes to launch the programme next year, and says initial retrofits could start in the third quarter of 2004. Based on the unit tested on a 747-200 proof-of-concept flight in 2000, the -400 unit could be between 3.05m and 4.4m tall, says Inman. Two main concepts are being evaluated, one of which would effectively replace 747-400 winglets with the new blended composite design, while the other would involve adding a wingtip growing overall span to around 66.1m.
The company estimates block fuel savings over the 747-400 of around 4% from the modification based on the initial -200 results. APB winglets studies are also under way for the 757, 767 and MD-80.