Aviation Partners Boeing (APB) obtained US Federal Aviation Administration certification of its blended winglet retrofit for the Boeing 737-700 at the end of August following the installation of an initial shipset on the first of four aircraft destined for Kenya Airways.
APB says a final decision has yet to be made on whether the winglet will be offered by Boeing as a production line option, as with the -800, though the higher costs associated with the structurally different -700 wing are expected to weigh against the move. APB vice president programmes Jay Inman says: "They're still assessing whether to go on the production line or not. It basically comes down to the cost to redesign the wing, and customer demand."
Unlike the heavier -800 wing, designed for the higher maximum take-off weights of the longer version, the -700 wing requires upper and lower skin strengthening to take the winglets, and modifications to the spars and stringers.
As a result, APB has focused on a relatively fast retrofit package for the -700 which, in the case of the first Kenya aircraft, took nine days at AMS in Phoenix, Arizona. "We expect to get it down to six days or less," says Inman. Reducing aircraft down time is a critical "make or break" factor in selling the retrofit. The joint venture says agreements have also been reached with CSA in the Czech Republic and for FLS in the UK to offer the modification.
Other than the Boeing Business Jet (BBJ), the 737-800 is the only new-build 737 model offered with forward fit or retrofit winglets from APB. The launch customer, German charter airline Hapag Lloyd, has retrofitted 12 -800s to-date, while other users include South African Airways and American Trans Air - the latter two having assembly line winglets installed on new -800s. Polynesian Airlines has also opted for the modification.
APB, meanwhile, plans certification flight tests of a winglet-equipped 737-300 early in 2002. A proof-of-concept test programme was completed on a leased aircraft earlier this year, and a production-standard retrofit design is being readied for the certification effort in 2002. Tests have indicated the need to increase span, as well as add the basic winglets, says Inman. The proposed 737 Classic blended winglets are expected to cut cruise specific fuel consumption by between 6% and 7%, almost double the savings gained on the -800.
Source: Flight International
