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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
L47019
A
747-400 MAINTENANCE MANUAL
 SPEED SENSOR - REMOVAL/INSTALLATION
___________________________________
 1.  General_______
 A.  This procedure has these tasks:
 (1)  
A removal of the speed sensor N1

 (2)  
An installation of the speed sensor N1

 (3)  
A removal of the speed sensor N2

 (4)  
An installation of the speed sensor N2.

 B.  
The load compressor speed sensor is referred to as speed sensor N1. The accessory gearbox speed sensor is referred to as speed sensor N2.

 C.  
Speed sensor N1 is installed on the top left side of the load gearbox. You can find speed sensor N1 above the left ac generator and the left side of the cooling air fan. Speed sensor N2 is installed on the left side of the accessory gearbox.

 D.  
Speed sensor N1 is installed in the load gearbox with the two nuts and two screws. These two screws are used during the removal procedure to prevent damage to the speed sensor N1.

 E.  
Speed sensor N2 is installed on the accessory gearbox with the two nuts and two-hole spacer.

 TASK 49-61-02-004-001
 2.  Speed Sensor N1 Removal (Fig. 401)_______________________
 A.  Access
 (1)  
Location Zones
 221 Control Cabin - Left
 222 Control Cabin - Right
 310 Fuselage - Station 2360 to Station 2792

 (2)  
Access Panels
 317AL APU Access Door - Left
 318AR APU Access Door - Right

 B.  
Prepare for the Removal

 S 864-002
 (1)  
Make sure the APU control switch on the P5 overhead panel is OFF and attach a DO-NOT-OPERATE tag.

 S 864-003

 (2)  
Open these circuit breakers and attach DO-NOT-CLOSE tags:

 (a)  
P6-2 Main Power Distribution Panel
 1) 6K18, APU ALTN CONT

 (b)  
P83 Aft APU Equipment Control and Circuit Breaker Panel 1) APU PRIME CONT

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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.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

 S 014-004
 (3)  
Open the left APU access door, 317AL, and right APU access door, 318AR:

 (a)  
While you hold the two APU access doors in the closed position, open the six latches on the right access door.

 NOTE: The left access door will open fully and the right
____ access door will drop approximately one inch (2.5 cm) from the fuselage frame when the last latch is opened.
 NOTE: A lanyard is attached to the aft end of the right access
____ door to hold the access door to the APU compartment bulkhead.
 CAUTION: BE CAREFUL NOT TO MOVE THE TWO APU ACCESS DOORS TO THE
_______ OUTBOARD SIDE FROM THE FULL OPEN POSITION. THE FULL OPEN POSITION IS WHERE THE APU ACCESS DOOR IS DOWN AND THE TWO HOLD-OPEN RODS ARE CONNECTED TO THE TWO BRACKETS ON THE APU COMPARTMENT BULKHEAD. DAMAGE TO THE ELEVATOR CONTROL SURFACES CAN OCCUR.
 (b)  
Open the left access door to the fully open position and remove the two hold-open rods from the two clips.

 (c)  
Remove the two quick-release pins from the two brackets on the left APU compartment bulkhead.

 (d)  
Connect the two hold-open rods from the left access door to the two brackets and install the two quick-release pins.

 (e)  
Push the right access door up and remove the lanyard from the pin on the aft APU compartment bulkhead.

 (f)  
Open the right access door to the fully open position and remove the two hold-open rods from the two clips.

 (g)  
Remove the two quick-release pins from the two brackets on the right APU compartment bulkhead.

 (h)  
　
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