(a)  
Remove the nuts and the washers that attach the inspection cover for the high impeller to the accessory drive adapter.

 (b)  
Remove the inspection cover from the accessory drive adapter.

 CAUTION:_______DO NOT USE FORCE TO INSTALL THE GUIDE TUBE. THE GUIDE TUBE MUST EASILY INSTALL IN THE PORT. DAMAGE TO THE GUIDE TUBE CAN OCCUR.

 (c)  
Install the PWC 41493 guide tube in the borescope inspection port for the high impeller. 1) Attach the guide tube to the boss.

 CAUTION:_______BE VERY CAREFUL WITH THE BORESCOPE DEVICE. THIS DEVICE CAN BE EASILY DAMAGED. DO NOT TWIST OR HOLD THE DEVICE TIGHTLY. DO NOT LET THE BORESCOPE DEVICE FALL TO THE GROUND. DAMAGE TO THE BORESCOPE CAN OCCUR.

 (d)  
Connect the fiberscope cable to the light source.

 1)  Adjust the light intensity to make the light brighter if it is necessary.
 EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú
 49-21-00
 ALL  ú ú 01 Page 611 ú Feb 10/97
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A 
747-400 
MAINTENANCE MANUAL 
A 
INLET CASE 
A 
COVER 
WASHER 
NUT 
HIGH 
A  IMPELLER 
SEE  A 

SEE  B 
HIGH IMPELLER 
FWD  INSPECTION AREA GUIDE TUBE 
Figure 604 (Sheet 1) High Impeller Borescope Inspection A-A 

EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú
 49-21-00
 ALL                    ú ú                      01        Page 612 ú                               Feb 10/91
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400
MAINTENANCE MANUAL

 CAUTION:_______ MAKE SURE THE ACTUATOR LEVER FOR THE DISTAL TIP IS IN THE
 NEUTRAL POSITION WHEN YOU INSTALL OR REMOVE THE BORESCOPE.
 THIS WILL PERMIT THE TIP TO MOVE FREELY IN THE GUIDE TUBE.
 CAUTION:_______ MAKE SURE YOU LET 40 MINUTES GO BY AFTER AN ENGINE
 SHUTDOWN BEFORE YOU DO THE INSPECTION.  DAMAGE TO THE

 BORESCOPE CAN OCCUR IF THE APU IS TOO HOT.
 (e)  
Slowly install the borescope tip in the guide tube while you look through the eyepiece. 1) Stop the installation when you can see the high impeller.

 (f)  
On the rear of the accessory gearbox, remove the two nuts and the washers that attach the crank cover to the gearbox (View B, Fig. 601).

 (g)  
Remove the crank cover with the PWC 41325-001 puller. 1) Remove and discard the packing.

 (h)  
Attach a wrench to the square end drive of the gear shaft.

L.E.

ANY NICK OR DENT IN THIS AREA MORE THAN 0.250 INCH (6.350 mm)OF THE BLADE L.E. HEIGHT IS NOT PERMITTED.

High Impeller Borescope Inspection
Figure 604 (Sheet 2)

EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú
 49-21-00
 ALL  ú ú 01 Page 613 ú Feb 10/97
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400
MAINTENANCE MANUAL

 CAUTION: MAKE SURE THE BORESCOPE DISTAL TIP DOES NOT ENGAGE THE
_______ HIGH IMPELLER BLADES. DAMAGE TO THE BLADES AND THE BORESCOPE CAN OCCUR WHEN YOU TURN THE LOAD SECTION.
 (i)  Examine the high impeller while a different person slowly turns the high rotor with the wrench: 1) Visually examine the high impeller to make sure it is in
 the inspection limits (Ref Fig. 604).
 a) Cracks in the impeller blades are not permitted.
　
中國(guó)航空網(wǎng) www.k6050.com
航空翻譯 www.aviation.cn
本文鏈接地址：747-400 AMM 飛機(jī)維護(hù)手冊(cè) 機(jī)載輔助動(dòng)力 1(147)