Downloaded from https://www.everyspec.com ADS-79D-HDBK data: iron (fe) mass versus date FIGURE M-4: Cumulative trend plot for on-line sensor M.6 SPECIFIC GUIDANCE The implementation of oil condition and debris monitoring is a program approach rather than the application of individual test methods. Failure modes should be analyzed to determine the best method/technique for detecting the failure modes. These techniques should then be periodically assessed to determine the performance of the chosen method. The following subsections provide specific guidance for oil condition and debris monitoring in a condition based maintenance program.
While traditionally oil condition and detailed wear debris analyses are ‗off-aircraft‘ in legacy systems, state of the practice sensors are available for ‗on-aircraft,‘ in- line measurements of oil debris and should be built into newer weapon systems, as previously cited, herein, for the F135, F119, and PW1000G engines. M.6.1 Testing methodologies: There are a wide variety of testing techniques and technologies utilized for in-service oil testing. They are grouped into the broad categories of off- aircraft (laboratory and at-line) and on-aircraft (on-line and in-line) testing. M.6.1.1 Off-aircraft Laboratory: AOAP provides in-service oil analysis services to the Army worldwide.
Oil samples are taken from the recommended machine components and sent to an Army laboratory. [Army standards in references M.2.1.a-d and t-cc] A multitude of tests are performed as determined by the component failure modes. Examples are provided in the subsequent paragraphs of this section. M.6.1.1.1 Off-aircraft Testing: The major advantage of off-aircraft oil testing is the wide range of tests available allowing for routine tests to be supplemented with additional, more detailed examinations, as needed. With off-aircraft testing (the current Army practice), substantial historical data and associated limits and trends are available.
However, there are inherent problems associated with all off-aircraft sampling procedures such as contamination while sampling, improper sampling procedures (location, tools, consistency), poor sample representation (abnormal wear in particular), analysis time, inconvenience, manpower, and cost. 246