In another effort to control repair costs, Southwest Airlines Co. plans to retrofit at least 176 aircraft with engine fan cowls of aluminum, replacing cowls of carbon epoxy composites. ``Composites are one way to do the job, but they're not a cost-effective way from a maintenance standpoint,'' said Ben Harpe, technical services director. ``We approached Boeing [Co.] two years ago, but Boeing chose not to step up'' to the problems of the cowl delamination, erosion and engine oil absorption.
As a result, Southwest placed an order March 20 with Aeronca Inc. of Middletown, Ohio, for the design and production of replacement fan cowls for 150 aircraft with a minimum value of $15.75 million and options of cowls for 50 more aircraft with a value of $5.25 million.
The change adds weight. A set of 737 aluminum fan cowls weighs about 60 pounds more than composite cowls. Aeronca will begin designs immediately, and replacements could be shipped to Southwest as early as the end of the year, Harpe said.
The low-cost, short-haul carrier will replace composite cowls on 151 737-300s, including 20 new aircraft that Boeing will deliver this year and on 25 737-500s. Twenty-five more 737-300s on order for 1996 delivery will get similar treatment.
Last year, as the kick-off customer, Dallas-based Southwest specified the use of aluminum for fan cowls in agreeing to buy 63 of Boeing's Next-generation 737 twinjets from 1997-2001.
Boeing had delivered 2,681 of its most popular airliner through January, and has 142 firm orders and 116 options for the 737-600, -700 and -800 models.
Beginning with the 737's introduction in 1967, Boeing used aluminum for fan cowls, switched to lightweight composites in 1986 and will return with the new series to aluminum, largely because other airline operators agreed with Southwest's unhappiness about the durability of composites in that application.
Aeronca, as an aircraft subcontractor, makes sheet-metal components, nozzles, plugs and polymer-matrix-composite tail cones.
