(2)  
An installation of the inlet pressure sensor (P1).

 B.  
The air pressure sensor is referred to as the inlet pressure sensor (P1).

 C.  
The inlet pressure sensor is on the bottom left aft side of the air inlet plenum.

 TASK 49-61-06-004-001
 2.  Inlet Pressure Sensor 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

 S 014-019
 (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.
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747-400 MAINTENANCE MANUAL
 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)  
Connect the two hold-open rods from the right access door to the two brackets and install the two quick-release pins.

 C.
Inlet Pressure Sensor Removal

 S 024-005
 CAUTION: MAKE SURE YOU DO NOT HIT THE AIR INLET PLENUM WITH YOUR HANDS
_______ OR YOUR TOOLS. DAMAGE TO THE AIR INLET PLENUM CAN OCCUR.
 (1)  
Do these steps to remove the inlet pressure sensor (2):

 (a)  
Disconnect the electrical connector D95009 (P9) (1) from the inlet pressure sensor (2).

 (b)  
Loosen the nut on the inlet pressure sensor (2) until you can remove the inlet pressure sensor from the adapter.

 (c)  
Remove the inlet pressure sensor (2) and packing (3). 1) Discard the packing (3).

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