This SAE Aerospace Information Report (AIR) was written because of the growing interest in aircraft installed outdoor engine testing by the Federal Aviation Administration, airlines, charter/commercial operators, cargo carriers, engine manufactures and overhaul and repair stations. This document was developed by a broad cross section of personnel from the aviation industry and government agencies and includes information obtained from a survey of a variety of operators of fixed and rotary wing aircraft and research of aircraft and engine maintenance manuals.<p>This document will provide aircraft operators with an overview of current industry on-the-wing engine test practices including advantages/disadvantages derived, test criteria, capabilities of remote ground-based test data acquisition/instrumentation and on-board condition monitoring systems, aircraft installation effects, and a general discussion of procedures, data, equipment and personnel required to perform safe, accurate, on-the-wing engine tests. This information is provided as a guide to help operators decide to initiate, improve, expand or cease performing installed engine testing.
This revision is being issued to update the information contained in the report where necessary and to add information regarding the provision of facilities that can be used for outdoor on-wing testing. This SAE Aerospace Information Report (AIR) has been written to develop an understanding of the principle differences between installed (or on-wing) outdoor engine testing and tests that are typically undertaken in a purpose build engine test cell for the engine removed from the airframe. Because of these differences it is necessary to outline firstly the limitations of outdoor on-wing testing and to explain what these are based upon. Typically, these limitations can be environmental or can be equipment limited, but in some cases measurements undertaken in a test cell are at present impractical for on-wing testing. The report information has been developed through a broad research of industry specialists and review of specialist airframe maintenance manuals and technical documents that describe the processes currently used for such tests. In order to illustrate the typical scope of on-wing outdoor testing, this paper uses some specific airframe and engine examples for turbofan, turboprop and helicopter tests. These give guidance regarding a wide range of considerations necessary for successful outdoor on-wing testing, however, appropriate and accurate data for any tests should always be obtained from the equipment manufacturer prior to undertaking any test activity. The paper also covers the practical benefits of installed outdoor testing and gives examples, many of which relate to time and cost, but also the benefit of the engine being mounted on the airframe, and as a consequence while undertaking the tests, utilizing the actual services and controls that will be used in flight.