brake horsepower. See BHP.
14 CFR Part 1: “The power delivered to the propeller shaft (main drive or main output) of an aircraft engine.”
brake lining (aircraft landing gear component). A material with a high coefficient of friction and the ability to maintain its friction and strength when it is hot. Brake linings were at one time made with asbestos, but modern brake linings contain no asbestos.
brake mean effective pressure. See BMEP.
brake specific fuel consumption. See BSFC.
braking action advisories. A condition noted in an ATIS broadcast when the tower has received a runway braking action report of “poor” or “nil.” When a braking action advisory is in effect, ATC will issue the latest braking action report for the runway in use to all arriving and departing pilots.
braking action report. A report of conditions on the airport movement area providing a pilot with a degree/quality of braking that he might expect. Braking action is reported in terms of good, fair, poor, or nil.
brashness (wood condition). A condition of wood which causes it to have low shock resistance so that it fails abruptly when it is bent.
brass. An alloy of copper and zinc made up of approximately 67% copper and 33% zinc. Brass is malleable and ductile and is used for certain types of aircraft hardware and locking wire (safety wire) where corrosion resistance is important.
Brayton thermodynamic cycle. The constant-pressure cycle of energy release used to describe the action of a gas turbine engine. Fuel is added to the air passing through the engine and is burned. Heat from the burning fuel-air mixture expands the air, and since this air is not confined, it accelerates as it moves through the engine.
The Brayton cycle, a constant-pressure cycle, is an open cycle because all the events, compression, combustion, expansion, and exhaust take place at the same time, but in different locations within the engine.