adjust. To change a condition to make it more satisfactory or to make it operate better. We adjust the hands of a clock so they show the correct time, and we adjust the fuel-air mixture on the carburetor of a reciprocating engine to get the proper mixture ratio for the best operation of the engine.
adjustable-pitch propeller. An aircraft propeller which has provisions for adjusting the pitch of the blades on the ground when the engine is not running.
adjustable split die. A tool used for cutting external threads on round stock.
The circular die has a split from the threaded hole in its center to its edge. An adjusting screw can spread this split to adjust the depth of the threads being cut.
adjustable stabilizer (airplane flight control). A horizontal stabilizer that can be adjusted in flight to trim the airplane, so it will fly hands-off at any given airspeed.
Administrator (FAA). The politically appointed head of the Federal Aviation Administration. 14 CFR Part 1: “The Federal Aviation Administrator or any person to whom he has delegated his authority in the matter concerned.”
admittance (electrical characteristic). The ease with which alternating current can flow in a circuit. Admittance (Y) is the reciprocal of impedance (Y = 1/Z) and is expressed in siemens. It was formerly expressed in mhos (ohm spelled backward).
AD oil (ashless dispersant oil). A mineral-base lubricating oil used in reciprocating engines. This oil does not contain any metallic ash-forming additives, but has additives that disperse the contaminants so they remain suspended in the oil, preventing their clumping together and forming sludge. The contaminants remain in the oil until they are removed by the filters.
advance. To move forward.
advanced composites. High-strength structural materials made by encapsulating a fibrous material in a resin matrix. Advanced composites have superior strength and stiffness and are light-weight. Kevlar and graphite fibers encapsulated in an epoxy matrix are widely used in modern aircraft construction.