S 426-012-N00
(1) Install the MCD probe into the valve (AMM 79-21-10/401).
S 416-013-N00
WARNING: OBEY THE INSTRUCTIONS IN AMM 78-31-00 HWEN YOU CLOSE THE THRUST
_______ REVERSERS. IF YOU DO NOT OBEY THE INSTRUCTIONS, INJURY TO PERSONS OR DAMAGE TO EQUIMENT CAN OCCUR.
(2)
Close the thrust reversers (AMM 78-31-00/201).
S 416-014-N00
(3)
Close the core cowl panels (AMM 71-11-06/201).
(4)
Close the fan cowl panels (AMM 71-11-04/201).
S 416-016-N00
(5)
Do the activation procedure for the thrust reversers
(AMM 78-31-00/201).
S 416-015-N00
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TASK 79-21-10-206-017-N00
3. Do the Visual Inspection of the Magnetic Chip Detectors_______________________________________________________
A. General
(1)
This procedure gives the instructions to examine the contamination found on the magnetic chip detectors (MCD). Do a Spectroscopic Analysis to find the type of contamination and the quantity of composition of the contamination.
(2)
There are four types of contamination: build debris (contamination from the assembly of the engine), fines, flakes, and chips.
(3)
If there is contamination, make a record of the position of the MCD probe. Examine the MCD probe with 20X magnification. Make a record of the quantity and type of contamination that is found.
B.
References
(1)
AMM 79-21-05/401, Main Oil Filter
C.
Do the Visual Inspection of the MCD Probe
S 216-018-N00
(1) Find the type of contamination that is found on the MCD probe:
(a) Build debris show as curly steel wool, shavings, or burrs.
NOTE: The build debris collects during the early steps of
____ engine operation after the assembly of the engine. This is the remaining material which stays in or goes into the engine during the assembly. The build debris usually comes from the machine operation when the components are made or assembled.
(b) Magnetic fines show as very small particles less than 0.010 inch (0.254 mm) in length and with different widths.
NOTE: When the engine components usually wear, they can cause
____ a small quantity of fines. You can keep the engine in operation with this condition. Fines can also be caused from a bearing skid and if a part (such as spacers, seal plates, and shaft plugs) turns. You cannot keep the engine in operation in this condition. Other engine operations show that only the bearing for the deoiler idler gear in the main gearbox has bearing skid that will make fines.
1) They show as black or gray sludge or fuzz on the MCD probe. 2) When the oil on the MCD probe is removed, the magnetic fines show as thin dim slivers. 3) The magnetic fines are usually found in engines which have low hours of operation and small quantities of maintenance.
4) If there are fines on less than 50 percent of the tip circumference of the MCD probe, the engine can continue in operation. a) Obey the usual time limit for the inspection of the MCD
probe.
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////////////////////////A / PW4000 SERIES /747-400 / ENGINES/MAINTENANCE MANUAL ////////////////////////
b) Do not do the necessary steps which are in the procedure to correct the magnetic fines problem.
(c) Chips are very thick pieces of metal where one surface is
usually smooth and the other surface is rough or irregular.
NOTE: The chips from ball and roller bearings are usually
____ smooth and shiny on one side. This side can show the initial manufacture process. The opposite side is not as shiny and looks like a fracture has occurred. The chips from gearteeth have one shiny side with machine marks and one side that is smooth and not shiny.
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