cermet. Any of a group of strong, heat-resistant materials made by sintering metals with ceramic. Sintering is a process of pressing powdered materials together under enough heat that they are almost, but not, quite melted. Cermet, also known as ceramet, or metal ceramic, is used to make turbine blades for gas turbine engines.
certificated aircraft. An aircraft whose design specifications meet at least the minimum requirements specified by the Federal Aviation Administration for the particular type of aircraft.
An approved type certificate (ATC) is issued for the aircraft design, and when an aircraft is built according to these specifications and maintained in such a way that it continues to meet these specifications, it is considered to be legally airworthy.
certificated technician. A type of aviation maintenance personnel included in the proposed 14 CFR Part 66 Aviation Maintenance Personnel. An Aviation Maintenance Technician (AMT) certificate with an Aircraft rating is proposed to replace the Mechanic certificate with both Airframe and Powerplant ratings.
Another certificate, also proposed under this regulation, is Aviation Maintenance Technician (Transport) (AMT-T). This certification allows the holder to perform certain maintenance and inspection operations on the appropriate air transport aircraft certificated in the United States by the FAA.
Certificate of Airworthiness. See Airworthiness Certificate.
cesium. A soft, silvery-white, ductile, metallic chemical element. Cesium’s symbol is Cs, its atomic number is 55, and its atomic weight is 132.905. Cesium is an important element used in the manufacture of photoelectric cells.
CFR engine. A special test engine used by the Cooperative Fuel Research to determine the octane rating of a hydrocarbon fuel. A CFR engine has a variable compression ratio, and it can be adjusted to cause any fuel being tested to detonate, or explode, rather than burn evenly. The fuel being tested is run in the CFR engine and the compression ratio is adjusted until the fuel detonates.
With the engine adjusted to cause detonation, the fuel under test is shut off, and a reference fuel, which is a mixture of iso-octane and normal heptane, is directed into the engine. The ratio of the iso-octane to heptane is changed until the reference fuel detonates the same as the fuel being tested.
The percentage of iso-octane in the reference fuel having the same detonation characteristics in the CFR engine as the fuel being tested is the octane number given the fuel.
CFRP (carbon fiber reinforced plastic). A high-strength, high-stiffness composite material made of carbon fibers encased in a resin matrix.
CG (center of gravity). The point in an object at which all of the weight is considered to be concentrated. The algebraic sum of the moments about the center of gravity is zero. The center of gravity may be expressed in inches from the datum or in percent of the mean aerodynamic chord.
Center of gravity may also be thought of as the point within an object about which all the moments trying to rotate the object are balanced.
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