<title>Radar to detect foreign object ingestion by a jet engine</title>

Abstract

Each year commercial, private and military aircraft jet engines are damaged by the ingestion of foreign objects. Annual engine repair costs for ingestion damage is in the tens of millions of dollars. Bird strikes represent the major foreign object threat to aircraft engines, although large hail and objects found on the ramp can also damage an engine. A radar based foreign object ingestion detection system concept, the subject of this paper, is capable of determining when an object as small as 4 millimeters has entered a fan jet engine. Additionally, such a system is capable of determining the relative size of the object and the approximate point within the engine where the object impacts the engine. These data can be displayed in real time to the pilot. In addition, the information recorded in the data base can be used by the mechanics between major engine inspections to determine if a detailed inspection of the turbine blade roots or other hard to access engine parts is required. Long term statistical data developed by the system can also be used as a measure of the foreign object and bird ingestion problem at various airports and improve the reporting of ingestion and bird strike events above the currently estimated 20 percent reporting rate.