本航空航天推荐规程（ARP）概述了适用于直升机安装的裸涡轴发动机室内噪声测试的推荐测试程序、数据收集和准备方法。应当认识到，自由场测量是优选的。

This Aerospace Recommended Practice (ARP) outlines a recommended test procedure, data collection and preparation method for indoor noise tests of a bare turboshaft engine suitable for helicopter installations. It should be recognized that free field measurements are preferable.