S 286-215-N00
(2)
If you find contamination, do the steps that follow to do an analysis of the contamination.
(a)
Examine the contamination.
NOTE: Data collected by persons shows that the inspection of
____ the magnetic chip detectors is very sensitive. The start of bearing and gear deterioration will release very small particles which will go through the oil system to the magnetic chip detector. You must be very careful when you try to find what parts the particles came from. A high power, 30 to 50X, magnification will help you do the analysis.
(b) Look for the chip properties.
NOTE: Particles that are made by spalling usually are shiny
____ rounded chips with one surface that is different from the opposite surface. The outer surface is highly polished and can have parallel dents, but the other surface will be rougher, or granular, or have waves. Particles are thin with thinner edges and open cracks. When the surface layer becomes fully worn, the layer below starts to break. This layer below is rougher, not as bright, and has many sharp cracks. Thin chips that are made by spalling are usually harder and less easily bent than other contamination.
(c)
If you cannot find the source of a chip, do a spectrographic analysis to help you find which elements are in the chip, the chip composition.
(d)
Refer to the Chip Composition Table which shows the percent of elements in parts which can make chips.
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No. 8 - Oil System Contamination Inspection
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~.............................................................................. | CHIP COMPOSITION TABLE | | | ................................................................................ | | MAIN OIL | OTHER | | | SOURCE | PUMP GEARS | GEARS | BEARINGS | ................................................................................ | | | | AMS 6441 | AMS 6490 | | SPECIFICATION | AISI H-13 | AMS 6265 | AISI 52100 | PWA - 725 | | | | | PWA - 723 | PWA - 793 | ................................................................................ | COMPOSITION | | | | | | (PERCENT) | MIN - MAX | MIN - MAX | MIN - MAX | MIN - MAX | ................................................................................ | CARBON | 0.32 - 0.45 | 0.07 - 0.13 | 0.95 - 1.10 | 0.77 - 0.85 | | MANGANESE | 0.20 - 0.50 | 0.40 - 0.70 | 0.25 - 0.45 | --0.35 | | SILICON | 0.80 - 1.20 | 0.20 - 0.35 | 0.20 - 0.35 | --0.25 | | PHOSPHOROUS | --0.30 | --0.025 | --0.025 | --0.015 | | SULPHUR | --0.30 | --0.025 | --0.025 | --0.015 | | CHROMIUM | 4.75 - 5.50 | 1.00 - 1.40 | 1.30 - 1.60 | 3.75 - 4.25 | | NICKEL | ----| 3.00 - 3.50 | --0.15 | --0.15 | | MOLYBDENUM | 1.10 - 1.75 | 0.08 - 0.15 | --0.10 | 4.00 - 4.50 | | COPPER | ----| --0.35 | --0.15 | --0.10 | | VANADIUM | 0.80 - 1.20 | ----| ----| 0.90 - 1.10 | | COBALT | ----| ----| ----| --0.25 | | TUNGSTEN | ----| ----| ----| --0.25 | | IRON | REMAINDER | REMAINDER | REMAINDER | REMAINDER | 2.................…..............…..............…...............…..............1
S 286-214-N00
(3)
If you know the source of the contamination, do the steps that follow to find if there is more contamination:
(a)
If the particles you found are from the gears or bearings, do the steps that follow. 1) Remove the engine (AMM 71-00-02/401). 2) Examine the bearings and gears.
(b)
If the particles are from a repair, operate the engine as follows: 1) Flush the oil system (AMM 12-22-03/301). 2) Fill the oil system (AMM 12-22-03/301). 3) Start the engine and operate it at minimum power until the
temperature of the oil is more than 150°F (65.6°C)
(AMM 71-00-00/201).
4) Increase the speed to 1.35 to 1.40 EPR and then operate the
engine at minimum power.
a) Do this four more times.
5) Operate the engine at 1.35-1.40 EPR for 10 minutes. 6) Do the engine shutdown procedure (AMM 71-00-00/201).
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