Transmission damage was not identified through oil analysis

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A laboratory made oil analysis to samples drawn from a Dana Spicer transmission (model 15.7 TE 32418-52). Below you’ll find previous analysis results from samples taken in Nov07 (981 hours) and March 08 (last sample 300 oil hours). Oil is Dexron III as recommended
(Nov 07/ March 08)
Viscosity 100C_ 5,29 cSt (March 08)
Water= 0% / 0%
TAN: 1,97 / 1,66
Copper: 0 / 0 ppm
Iron: 15/ 12 ppm
Chromium: 0 / 0 ppm
Lead: 7/ 0 ppm
Aluminum: 3 / 5 ppm
Silica: 3 / 8 ppm
The oil was changed and analysis was made (sample March 08). 2 weeks later (recommended oil Dexron III) a transmission failure took place. The client reported clutch discs and bearing damage. They are wondering (also myself) why this damage was not anticipated through oil analysis. Samples were taken with equipment in use or recently stopped.
Laboratory is certified and periodically evaluated since this belongs to a lubricant blending plant. Wear was measured through ICP Plasma (< 10 um) and values were very low. As I recall copper may indicate clutch material but still this metal was measured 0 ppm.
I don’t think asbestos could be determined.
Is it possible that a sudden failure could occur and it wasn’t possible to anticipate it ?
Any guidance or recommendations for further lab analysis will be appreciated.

4/14/084:53 PM

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badnewsbareMember

We have a similiar case with a screw air compressor, spectrometry is no good for detecting particles greater than 10 micron, our oil analysis (ICP) was showing only slightly elevated wear metals, the filters were plugging off prematurly, we sent a filter sample to the lab, they reported abnormal sliding wear (steel alloy), some particles greater than 100 microns, vibration tech reported no change at the time, two months later the vibes started climbing, we now pay close attention to filters, sightglasses and magnetic plugs because you cannot count on spectrometry alone

4/15/089:06 AM

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micbialMember

Another thing to consider is that a oil analysis can't tell you the actual structural condition of parts. If a part is stress fatigued (ie. cracked) it's not going to show up in a UOA. The clutch disc or bearings could have had structural deficiencies and just failed when they reached their breaking point. A UOA can only tell you so much.

4/19/0811:47 PM

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enriqueMember

Thanks for your comments

Since clutch discs were damaged i supposed copper would´ve been a guidance, as i could have read in several metal references. Do this apply to all clutch discs or it may be other metals/ non-metals involved in clutch discs in a heavy duty powershift transmission ??(Spicer for example)

4/21/086:29 AM

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