747-400 AMM 飞机维护手册 空调 AIR CONDITIONING 2(42)

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 NOTE: For cracks or damage which goes through the duct,
____ additional ply is required on the inside of the duct. Before applying this ply, you must clean the area.
 NOTE: For frayed surfaces of ONLY the top ply, (minor surface
____ damage) you may use 1 ply to repair the surface. This includes the area near the attachment holes. This will prevent further fraying.
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MAINTENANCE MANUAL

 S 348-015
 (6)  Impregnate each cloth patch with BMS 5-126, and place between two pieces of PVA parting film.
 NOTE: Weight of the adhesive must be equal the weight of the
____ dry fiberglass cloth to make the cloth absorb it.
 C. Place the Repair Patch
 S 348-009
 (1)  
Apply a layer of BMS 5-126 adhesive mixture, prepared with
 manufacturers instructions, on the repair area.

 S 348-028

 (2)  
Remove parting film from one side of the smallest ply of the patch and put its exposed face against the repair area.

 S 348-010

 (3)  
Use a squeegee to remove wrinkles and entrapped air on the parting film that has covers on the patch.

 NOTE:____Do not remove the adhesive with too much pressure. This can cause the adhesive patch to fail because there is not enough adhesive.
 S 348-011
 (4)  
Put the next larger size ply of the absorbed patch on the ply. Make sure there is a minimum of 0.80 inch (2.0 cm) overlap all around.

 S 348-012

 (5)  
Make sure you do the same for the other patches as shown in the steps above.

 NOTE: If possible, use a complete wrap around ram air duct for
____
 the third ply.

 S 348-020
 (6)  
After placing the last ply, cover the entire lay-up with a pice of parting film extending about 0.80 inch (2.0 cm) over the edges of the patch.

 S 348-029

 (7)  
Sweep excess adhesive to the edges of the parting film, fairing the edges of the patch to the contour of the repair surface. Make sure all loose threads are embedded in the resin.

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 S 348-030
 (8)  Wipe off any excess adhesive that has been pushed out at the edges of the parting film.
 D. Cure the patch.
 S 348-031
 (1)  Cure the patch. The required curing time for a BMS 5-126 adhesive mixture is about 12 hours at 70 deg F (21 deg C) or 1 hour at 130 deg F (55 deg C).
 NOTE: A cured patch is hard and resounds when tapped lightly with a
____
 coin or other light metallic object.

 S 348-033
 (2)  
Remove parting film from the patch after curing.

 S 218-035

 (3)  
The patch should be free from pits, blisters, starved areas and extra resin deposits.

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MAINTENANCE MANUAL

 FLOW CONTROL AND SHUTOFF VALVE FILTERS - REMOVAL/INSTALLATION
_____________________________________________________________
 1.  General
_______
 A.  The flow control and shutoff valve filters prevent contamination from entering the pneumatic control circuits of the valve. Two filters are installed in each flow control and shutoff valve.
 B.  This procedure has instructions to do the following tasks:
 (1)  
Flow control and shutoff valve filter removal.
　
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