S 426-004
 (3)  Do this task: "Elevator Power Control Unit Installation"
 (Ref 27-31-14/401).

 EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú

 27-31-14
 ALL  ú ú 01 Page 604 ú Jul 15/91
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
737-300/400/500MAINTENANCE MANUAL
 ELEVATOR PITOT-STATIC SYSTEM - MAINTENANCE PRACTICES
____________________________________________________
 1.  General
_______
 A.  This procedure contains 4 tasks. The first task flushes the elevator pitot-static system. The second task does an inspection of the drain lines. The third task is a system test of the elevator pitot-static system. The fourth task is an inspection of the pitot probes.
 B.  The removal/installation procedure for this pitot probe, can be located in AMM 27-31-94/401.
 TASK 27-31-17-172-009
 2.  Elevator Pitot-Static System Flushing
_____________________________________
 A.  Special Tools and Equipment
 (1)  
Dry air pressure source - 0-15 psi with filter and gage

 B.  
References

 (1)  
27-31-00/201, Elevator and Tab Control System

 C.  
Access

 (1)  
Location Zone
 702 Tail Compartment Access Door

 (2)  
Access Panels
 3701 Stabilizer Trim Access Door

 D.  
Procedure

 S 172-010
 (1)  
Flush the elevator pitot-static system (Fig. 201):

 (a)  
Disconnect the pitot lines from the pitot probes and the feel computer.

 (b)  
Remove the drain plugs from the pitot lines.

 (c)  
Flush the left pitot line with dry filtered air (not more than 15 psi or 698 knots) for 3 minutes.

 NOTE: Flush the pitot line at a different time from the probe
____ end, the feel computer end, and the drain plug end.
 (d)  
Flush the right pitot line with dry filtered air for 3 minutes.

 (e)  
Disconnect the drain lines from the feel computer.

 (f)  
Flush the two drain lines from each end with dry filtered air (not more than 15 psi or 698 knots) for 3 minutes.

 (g)  
Connect the pitot lines and the drain lines.

 (h)  
Install the drain plugs.

 S 212-001
 (2)  Make sure that there is no particle or roughness in all ports in the pitot-static system.
 EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú

 27-31-17
 ALL  ú ú 01 Page 201 ú Jul 15/94
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A

737-300/400/500MAINTENANCE MANUAL 
PITOT PROBE 
PITOT LINE 
SEE  A 
DRAIN PLUG BSEE  STATIC LINE COMPUTER FEEL 
FWD  A  STATIC LINE  PITOT LINE 

LOCKWIRE
FWD
DRAIN PLUG
DRAIN PLUG (ALTERNATE)
(PREFERRED) (2 LOCATIONS)
(2 LOCATIONS)
B
B
Elevator Pitot Static System Figure 201
EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú

 27-31-17
 ALL  ú ú 01 Page 202 ú Jul 15/96
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A 737-300/400/500MAINTENANCE MANUAL
 S 792-002
 (3)  If it is necessary, do the leakage test of the pitot-static system in the System Test - Elevator Pitot-Static system.
 TASK 27-31-17-202-003
 3.  Pitot-Static System Drainage Inspection/Check (Fig. 201)
_____________________________________________
 A.  Access
 (1)  
Location Zone
 702 Tail Compartment Access Door

 (2)  
Access Panels
 3701 Stabilizer Trim Access Door

 B.  
Procedure