This excerpt taken from the BA 10-K filed Feb 28, 2005.
Raw Materials and Suppliers
We are dependent on the availability of energy sources, such as electricity, at affordable prices. We are also highly dependent on the availability of essential materials, parts and subassemblies from our suppliers and subcontractors. The most important raw materials required for our aerospace products are aluminum (sheet, plate, forgings and extrusions), titanium (sheet, plate, forgings and extrusions) and composites (including carbon and boron). Although alternative sources generally exist for these raw materials, qualification of the sources could take a year or more. Many major components and product equipment items are procured or subcontracted on a sole-source basis with a number of domestic and foreign companies. We are dependent upon the ability of our large number of suppliers and subcontractors to meet performance specifications, quality standards, and delivery schedules at anticipated costs, and their failure to do so would adversely affect production schedules and contract profitability, while jeopardizing our ability to fulfill commitments to our customers. We maintain an extensive qualification and performance surveillance system to control risk associated with such reliance on third parties.