Book Description

The purpose of this 3-volume study was to consider the feasibility of establishing an FAA requirement for a manufacturer of aircraft engines to demonstrate compliance with an engine noise-level standard in order to obtain an engine-noise type certificate. The objective of engine-noise type certification (if feasible on the basis of economic reasonableness, technological practicality, and appropriateness to the type design) would be to supplement the aircraft-noise type certification requirements in Part 36 of the Federal Aviation Regulations. This study was limited to aircraft jet engines. Volume 3 describes the selection of a concept for the noise-evaluation quantity, namely the A-frequency-weighted sound power made nondimensional by a power-like quantity equal to the product of total net static thrust and the speed of sound in the ambient air. The recommended independent variable is total net static thrust made nondimensional by the product of total mass flow rate and the speed of sound in the ambient air. Farfield 1/3-octave-band sound pressure levels, measured around production and experimental versions of aircraft turbojet and turbofan engines, were used to test the utility and applicability of the recommended noise-evaluation quantity. Engines ranged in rated static thrust from 11 kN to 222 kN (2500 lb to 50,000 lb). For certification purposes, a certifying authority would select appropriate limits on the magnitude of the noise-evaluation quantity applicable to thrust settings representative of takeoff and landing approach.