Abstract
The Advanced General Aviation Transport Experiments (AGATE) Consortium is a cost-sharing industry-university-government partnership initiated by NASA to create the technological basis for revitalization of the U.S. general aviation industry. It was founded in 1994 to develop affordable new technology as well as the industry standards and certification methods for airframe, cockpit, flight training systems, and airspace infrastructure for next generation single pilot, 4–6 place, near all-weather light airplanes. The AGATE consortium has more than 70 members from industry, universities, the FAA, and other government agencies.
With respect to the advanced materials program within AGATE, the government-industry-academia program is directed toward the creation of material allowables that will be approved by the FAA for qualification of composite airframes — the first two being the Cirrus SR20 from Cirrus Design Corporation of Duluth, MN and the Lancair Columbia 300 from Pacific Aviation Composites of Bend, OR. These aircraft will be the first two all composite, four-seat AGATE-type airplanes to be certified in the United States. AGATE members Lancair, Cirrus Design, Cessna Aircraft, Raytheon Aircraft, Global Aircraft, Stoddard-Hamilton and Simula Technologies are contributing members in the program that promises to increase the level of sharing between competitors for the benefit of the entire general aviation industry.
One major goal of the advanced materials program is produce FAA approved certification methods for the use of composite materials within the general aviation community. A recently published document entitled “Material Qualification Methodology for Epoxy-Based Prepreg Composite Material Systems” has been approved which describes an acceptable program to substantiate that the materials and processes employed meet FAA requirements for a selected material system. This is the first FAA public document which “standardizes” the procedure for qualifying a composite material system which follows guidelines set forth by the MIL-HDBK-17 committee. These requirements apply to the original material qualification. Once certified, changes to the material, process tooling, and/or facility require a review and repetition of some (or all) of these tests may be required. The plan gives specific information about the qualification program for epoxy-based pre-impregnated carbon or fiberglass unidirectional tape and pre-impregnated carbon or fiberglass woven fabric cured and processed at or above 240 degrees Fahrenheit. Specifically, this plan covers qualification methodology for no-bleed prepreg systems manufactured using vacuum bag molding.
The properties of traditional materials — aluminum, steel, etc. — have long been accepted by the FAA in the design of airframes. These “allowables” mean the designer does not have to test every part to destruction, which is a very expensive, time-consuming process, but may use these allowable to substantiate the design using various forms of analysis. Due to company proprietary data restrictions, these “allowables” are generally not shared with other airframers which cause a repetition of qualification, sometimes for identical material. The AGATE database will attempt to standardize this data for a specific material system which will allow AGATE and non-AGATE companies to use the qualification data without having to completely repeat the full qualification [as depicted in Figure (1)]. The overall savings to the baseline qualification procedure should result in an “order of magnitude” savings in cost and over a factor of four savings in qualification time [as depicted in Figure (2)]. The overall goal of the program is to decrease to time and cost required for a new aircraft certification while still maintaining a high level of reliability and safety.
An Innovative Structural Fatigue Monitoring Solution for General Aviation Aircraft
