R NOTE : After the removal of each scavenge screen plug from the
____ R lubrication unit we recommend to attach a tag to it. This tag will R be pre-marked with the plug location related to the lubrication R unit housing. To this end, we remind you that the lubrication unit R (housing) casting is marked, on its bottom outer surface, with the R sump indications that are on line with each scavenge screen plugs. R From front to rear of the installed lubrication unit, these sump R indications read as follows: "REAR SCAV IN", "TGB SCAV IN", "FRONT R SCAV IN", and "AGB SCAV IN".
You can also use other indexing methods, such as matchmarking with (authorized) felt markers, as long as these methods are reliable and do not erase during handling and processing of the plugs.
(1) Remove ONE scavenge screen plug from the lubrication unit (Ref. TASK 79-21-10-000-007).
(2) Examine the particles you find in the screen with a magnifying glass R and a magnet to collect the magnetic particles from the non-magnetic R particles.
(3) Remove the oil from suspect materials with stoddard solvent (Material No. CP 2011) or white spirit (Material No. CP2010).
(5) Examine the particles with a magnifying glass.
R (4) Collect the pieces of material for investigation and identification R (Ref. NDTM Part 10) (Chip analysis).
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R R Inspection of the Scavenge Screens Figure 609/TASK 79-00-00-991-302
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B. Particles that can be identified:
(1) Do the maintenance actions that follow:
(a) If you identify bearing material (M50 or M50 Ni Li material), which is recognizable by a typical bright laminated flake appearance: Remove the engine (Ref. TASK 71-00-00-000-042).
(b) If you find bearing cage material (retaining tang), it comes from the No. 4 bearing: replace the No. 4 bearing at the next shop visit.
(c) If you find plastic/organic debris in the scavenge screen plug associated with the FWD sump, such as:
- glass fiber/polyimide material (greenish-brown color)
- phenolic/plastics material (greenish-white color)
- resin/polyimide material (green color):
This indicates a deterioration of the forward air/oil abradable
seal or of the forward air/oil separator ducts.
1 If such findings are made, the engine is SERVICEABLE as long
_ as the oil pressure and consumption stay in the limits.
2 However, do a check of the oil pressure and consumption during
_ the next 100 to 200 hours of engine operation.
R (d) If you find organic unwanted material from packings (O-rings),
R black broken pieces of materials, carbon unwanted material: the
R engine is SERVICEABLE as long as the oil pressure and consumption
R stay in the limits.
(e) The engine is also serviceable if you find:
1 Machining chips, generally recognizable as spring-like shape
_ R and/or with visible parallel marks of machine tools, when seen R under a magnifying glass.
2 Labyrinth seal rub strip, stainless steel with a sliver
_
shaving appearance.
(2) Generally, if the particles are not surely identified, send them to the laboratory for analysis. Do it specially for particles that you think contain bearing material.
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C. Particles that can not be identified:
(1) Magnetic particles:
CAUTION : IF YOU FIND A LARGE QUANTITY OF PARTICLES IN THE SCAVENGE
_______ SCREENS YOU MUST KNOW THAT SUBSEQUENT ENGINE OPERATION CAN MAKE THE ENGINE DAMAGE WORSE.
(a) NORMAL CONDITION: Less than four (4) particles with the largest one less than 0.01 in. (0.25 mm).
(b) MARGINAL CONDITION: More than four (4) particles with the largest less than 0.01 in. (0.25 mm), or less than four (4) particles with the largest more than 0.01 in. (0.25 mm) but less than 0.02 in. (0.5 mm):
1 Send the particles to the laboratory.
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