In-line oil debris monitor for aircraft engine condition assessment

Abstract

K1J 953, tel# (613) 744-3530 Failure Mechanism Dimensional Discrepancies Overrolling of Debris Corrosion Other FatigueAbsrrucr-The development of an in-line, full flow oil debris sensor for aircraft engine condition assessment is described. First used on the F22 fighter, this sensor is the only " all-metals" debris detector in production. The sensor is based on an inductive measurement technique which enables the system to detect, count and classify wear metal particles by size and type (ferromagnetic and nonferromagnetic) above a minimum particle size threshold. In flight, the measured count values are compared to preset levels to provide prognostic health information on the oilwetted components of the engine. This paper describes the sensor design requirements, principle of operation, electronic design and mechanical design features. The results of a test program established to correlate the oil borne debris measurements to component degradation characteristics and data from actual engine bearing failures, are also presented. FrequencyObserved (%) 29 24 35 10 2

Research on the Influence of Excitation Frequency on the Sensitivity in Metal Debris Detection with Inductor Sensor

“…It is observed that the equivalent resistance 2 is a formula of excitation frequency according to (8) and (9). The inductances 1 and 2 are unaffected by the excitation frequency.…”

“…The short-circuit loop resistance 4 of the ferromagnetic debris can be calculated with formula (8) and formula (9). So the changing rate of the microsensor coil inductance can be described as formula (15) while it detects ferromagnetic debris.…”

“…But the ferromagnetic debris has a large magnetic permeability, which makes the inductance of microcoil increase from 1 to 3 . Equations (12) can be obtained according to the equivalent circuit in Figure 2 As shown in (13), the equivalent impedance of the microsensor for ferromagnetic debris detecting can be got by solving (12). Consider…”

“…So the ferromagnetic debris and nonferromagnetic debris can be distinguished according to the rise or the decline of inductance, and the size of debris can be discriminated in light of the change of inductance [11,12]. The double-layer plane inductor coil and the solenoid inductor coil were adopted by Du and Zhe to detect metal debris in lubricant separately [13,14].…”

Comparison of optical and magnetic particle detection systems for detection of pitting damage in low speed hydraulic motors

“…They found that cumulative particle counting can be used to indicate the onset and progression of pitting damage in gears. A similar approach has been shown effective for damage detection in bearings [17]. These earlier studies all used inductive in-line sensors for particle detection.…”