747-400 AMM 飞机维护手册 STANDARD PRACTICES - ENGINE(17)

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 S 912-012-N00
 CAUTION: DURING THE REMOVAL OF THE PARTS THAT HAVE J THREADS, IDENTIFY
_______ THESE PARTS AND KEEP THESE PARTS TOGETHER. YOU CAN DAMAGE THE ENGINE, IF YOU INSTALL AN INCORRECT PART WHERE A J THREAD IS NECESSARY.
 (11) Nuts and bolts with J threads are used in many locations on the engine.
 (a)  The J threads have a full radius at the bottom on the threads and a larger minor diameter.
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(b)  
The J threads have a longer life, better stressed extension property, and more tension strength.

 (c)  
Nuts and bolts with the J threads and nuts and bolts with the usual threads are the same when you look at them. 1) Nuts and bolts have part numbers to show that they have the

 J threads.
 NOTE: Nuts or bolts smaller than 0.200 inch (5.080 mm)
____ in the length by 0.050 inch (1.270 mm) in the width have no part numbers.
 2)  A blue dye is used on the nuts and bolts with the J thread at the first engine assembly.
 NOTE: The blue dye will burn off during the operation
____ of the engine or will go away when you clean the engine.
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LOCKING METHODS - MAINTENANCE PRACTICES
_______________________________________
 1. General
_______
 A. This procedure gives the instructions for different lock devices.
 B. This procedure gives the data for the tasks that follow:
 (1)  
Cotter Pin Installation

 (2)  
Retaining Ring Installation

 (3)  
Tab Washer Installation

 (4)  
Cup Washer Installation

 (5)  
Lockwire Installation

 (6)  
Safety Cable Installation

 TASK 70-21-00-402-001-N00
 2. Cotter Pin Installation
_______________________
 A. Access
 (1)  Location Zone
 412 Engine No. 1
 422 Engine No. 2
 432 Engine No. 3
 442 Engine No. 4

 B. Procedure
 S 422-021-N00
 (1)  When you install a cotter pin in a nut, do these steps:
 (a)  
Tighten the nut until the torque is in the lower values of the range, unless a higher torque is specified. 1) Then tighten the nut until the slot aligns with the hole in

 the bolt shank.

 (b)  
If you get to the maximum torque before the slot and the hole align, assemble the nut again. 1) If you get to the maximum torque again, use a new nut.

 (c)  
If more than 50 percent of the cotter pin is above the castellation of the nut, install a new nut.

 (d)  
Make sure the head of the pin engages tightly in the slot of the nut.

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L-25172
TANGENT
MAKE SURE THE COTTER PIN HEAD IS SNUG AGAINST THE PIN SHANK. DO NOT BEND THE PIN HEAD.
MAXIMUM NORMAL
COTTER PIN/PIN INSTALLATION
L-25223
Cotter Pin Installation Figure 201
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(e)  
Make sure the axis through the eye of the cotter pin is perpendicular to the bolt shank (Fig. 201).
　
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