Composite Applications in Commercial Transport Aircraft

Abstract

Since the development of advanced fiber composite materials in the 1950s and 1960s, these materials, particularly carbon fiber/epoxy, have become increasingly important in commercial transport aircraft. These materials and the design/manufacturing technology for their application are now truly global.

To assure continued use of these materials to enhance aircraft performance, their life cycle costs must compete favorably with those of other materials. The two areas driving high composites costs are initial fabrication and repair. The composites industry must continue to demonstrate its commitment to provide value to its customers, the airlines, by aggressive improvements in those areas.

Significant use of advanced composites in commercial aircraft started when several new fibers with impressive structural properties were developed in the late 1950s and early 1960s. Primary among these were boron, graphite and carbon, aramid and S-glass. Resin matrix composites of these materials possess very high specific strength and/or modulus, making them attractive candidates for aircraft applications. By the late 1960s, testing and development had clearly identified carbon filaments as the fibers with the best overall balance of engineering properties, ease of manufacture, and cost. Industry interest in learning to use the materials led to the design, fabrication, and service evaluation of a number of commercial transport airplane components, such as the Boeing 727 elevators, Boeing 737 spoilers, Lockheed L-1011 inboard ailerons, and McDonnell-Douglas DC-10 rudders. Weight reductions averaging 25% were achieved.

New large commercial jet aircraft initiated in the late 1970s — the Boeing 757 and 767, and the Airbus Industries A310 — included the first widespread application of advanced composites to secondary structures. Subsequently, new and derivative models of existing aircraft, such as the MD-11, MD-80, B737, and A300, were introduced with similar composite components.

Pressure to reduce aircraft weight continued into the early 1980s. NASA sponsored programs aimed at the development of advanced composite primary structures for civil transport applications. The FAA and industry worked together to develop a means of showing compliance with the certification requirements. Certification of a composite Boeing 737 horizontal stabilizer was completed in 1982, and the McDonnell Douglas DC-10 composite vertical stabilizer was certified in 1984. A vertical fin was also developed for the Lockheed L1011, but was not introduced into commercial service. By the end of the 1980s, several new aircraft included advanced composite primary structures, including the Airbus Industries A320 and A330/A340, the Aerospatiale-Alenia ATR72, and the Boeing 777.