Current testing requirements for high temperature alloys are defined in general industry specifications (ASTM, AMS), as well as in user specifications. Many of these requirements were established in the 1960's when production practices were yet to be refined.
cowling - protective covering consisting of a metal part that covers the engine; there are powerful engines under the hoods of new cars; the mechanic removed the cowling in order to repair the plane's engine.
Â­Â­Generally, engines with dual overhead camshafts (DOHC) are higher performance engines, they produce more power, and can run at higher speÂ­eds. The camshafts have the job of opening the valves that let air into and exhaust out of the engine.