Section II: NONAERONAUTICAL EQUIPMENT ANALYTICAL METHODOLOGY

NAVAIR 17-15-50.4

TM 38-301-4

T.O. 33-1-37-4

CGTO 33-1-37-4

SECTION II

NONAERONAUTICAL EQUIPMENT ANALYTICAL METHODOLOGY

2-1. General.

a. Each moving part in a machine has a normal rate of wear. As machine components wear, microscopic

metallic wear particles are generated. Some microscopic particles are small enough to pass through a filter and

remain suspended in the lubricating oil. When a machine is operating normally and operated under normal

conditions, the concentration of these wear particles will be fairly consistent at the end of each oil change period.

However, differences in load and working environment will affect the rate of wear of the machine components, as

will various internal oil system problems and component friction changes. When abnormal wear takes place in the

equipment, the concentration of one or more elements will increase significantly. Therefore, the concentration of

wear particles will not always be the same and the evaluator must interpret the results of oil sample analysis to

determine the reason for the changes detected and the possible effects of these changes on the equipment.

b. The JOAP nonaeronautical analytical methodology encompasses the interpretation of used oil sample

analysis results, assessment of equipment and oil condition based on analysis results, diagnosis of the probable

sources of wear-metals and contaminants, and the issuance of accurate and effective equipment maintenance

and operational recommendations to the operating activity. The methodology uses wear-metal evaluation criteria

tables by type equipment and individual equipment diagrams (Appendix B and D) as well as subjective evaluation

of a series of laboratory test.

(1) The wear-metal evaluation criteria tables provide the wear-metal range and trend values which

relate the oil sample wear-metal concentration to the expected condition of the equipment or oil condition. These

tables also contain supplemental technical information to assist the evaluator in identifying the most probable

sources of wear-metal. For some equipment, the criteria have not been determined but will be added when

available. Data provided in these tables are intended for use as guidelines by evaluators, not as strict go/no-go

criteria. The guidelines were statistically derived using analysis of samples from operating equipment from

various geography locations. Absolute values that will indicate specific impending component failures may

actually be somewhat above or below the concentration levels shown. Therefore, the evaluator must apply

subjective judgement, experience, and knowledge of the particular component from which a sample is taken to

determine evaluation recommendations.

(2) The individual equipment diagrams present wear-metals source information keyed to location by

the use of equipment cutaway schematics. The cutaway or cross sectional figures for the equipment provide

detailed breakout information of metallic elements present in the equipment. In some instances, the figures

identify elements that will not be detected by the spectrometer. These elements are shown for evaluator

information only, with the possibility that they may be detected by other laboratory methods. In cases where the

major element for a component is known, it is indicated by being shown first and underscored. Generally, the

combinations of elements shown are listed in descending order of the amounts present in the components.

NOTE

The Engine/Transmission/Equipment Cross Index listing in Appendix B includes a

cross index for nonaeronautical equipment items. The end items shown in the

appendix for a particular engine or transmission may not be the only equipment which

utilize that particular engine/transmission.

2-2. Wear-Metal Sources.

a. Internal combustion engines are subject to contamination from external sources such as sand and dirt,

as well as internal sources, such as blow-by combustion contaminants and wear-metals from various oil-wetted

moving parts, which are deposited in the oil system in varying degrees, depending upon the equipment condition.

2-1