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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400
MAINTENANCE MANUAL

STA 
420 
STA 
340 
CREW ESCAPE HATCH 
SEE  A 

INSPECT FOR
STRINGER BODY SKIN CRACKS
CRACKS
OUTBOARD FLANGE
CRACKS

EXTERNAL SKIN
CRACKS

TEAR STRAP SPLICE CRACKS
SEE B
STRINGER CUTOUT STRINGER TIE
FRAME WEB CRACKS CLIP CRACKS
FRAME WEB AND FRAME WEB CRACKS
STRINGER CUTOUT REINFORCING ANGLE CRACKS
FWD STRINGER
FLOOR BEAM
FLOOR BEAM CRACKS
END CRACKS
END CRACKS FWD
INNER VIEW
B A
Control Cabin Inspection
Figure 602

EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú

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MAINTENANCE MANUAL

 NOTE: This procedure assumes that the fiberglass dripshield between BS
____
 360 and BS 380 left has been removed around stringer S0.
 NOTE: The procedure requires cutting access holes and slots in the drip
____ shields, and with the aid of a flexible borescope, visually inspecting the frames.
 NOTE: The borescope inspection may not be used on structures beyond
____ 20,000 flight cycles.
 NOTE: It is recommended that this inspection procedure be completed by
____ two persons, one controling the insertion tube, and the other viewing, directing and operating the manipulator.
 S 016-091
 (1)  Gain access to BS 340 frame right.
 (a)  
Lower the aft overhead circuit breaker panel P12.

 (b)  
Gain access to the panel opening, and locate the aft side of the fiberglass dripshield covering BS 340 frame at stringer S1R.

 (c)  
Cut a 3.0 inch diameter hole in the dripshield aft side, and cut a single slit in the insulation blanket. This hole is access hole A.

 NOTE: Make the access holes as small as possible and save
____ the pieces that you remove to make the repairs easier.
 (d)  
Remove the M154 fuel module panel and any other panels necessary to gain access to the frames.

 (e)  
Locate the aft side of the dripshield covering BS 340 frame at Stringer S6R.

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 (f)  
Cut a 3.0 inch diameter in the aft side of the dripshield, and cut a slit in the insulation blanket. This is access hole B.

 (g)  
Locate the forward side of the dripshield at stringer S7R and S8R, and between S9R and S10R.

 (h)  
Cut two 2.0 by 9.0 inch slots in the dripshield forward side, and slit the insulation blanket. These are access slots C1 upper and C2 lower.

 NOTE: The upper access slot C1 is not required if the BS 340
____ frame dripshield is removed along the aft end of the pilots right side window.
 S 016-092
 (2)  Gain access to BS 360 frame right.
 (a)  
Gain access to the inboard side of the BS 360 to 380 intercostal, located between stringers S1R and S2R, by cutting a 2.0 by 13.0 inch fore and aft slot along the center of the inboard side of the dripshield covering the intercostal. This is access slot D.

 (b)  
If the intercostal is cracked, cut and remove the dripshield section from the intercostal to the crown of the cockpit for repair access.

 NOTE: The intercostal has two 4.0 inch diameter lightening
　
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