Spirit AeroSystems Holdings, Inc. (NYSE:SPR) is the largest independent airplane parts manufacturer in the world. Eighty-seven percent of the company's revenues come from sales to Boeing ^[1], and SPR maintains an inventory of certified parts for almost all commercial and military Boeing aircraft, which are sold to Boeing who then distributes to the aftermarket. As a result, Spirit's fortunes are closely tied to Boeing's success. Boeing and its competitor Airbus both have record order backlogs, which speaks to the health of the market for these airplanes for years to come. However, high jet fuel prices make airplanes more expensive to operate - a potential wrench that could reduce demand for airplanes in the future. (Read more at Wikinvest )