BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A 
737-300/400/500MAINTENANCE MANUAL
 TASK 34-11-01-872-122
 3.  Drain the Pitot-Static System_____________________________
 A.  General
 (1)  The pitot static system should be drained periodically as specified
 in the 737 Maintenance Planning Document.  Also, the pitot-static
 system should be drained when the airplane has sustained ground
 exposure to very heavy rainfall.
 ú 
        ú
 NOTE:____ Very heavy rainfall is specified as rainfall that accompanies
 ú  a monsoon or a tropical thunderstorm.
 ú
 B. Drain System
 S 862-123
 (1)  Use these steps to drain the pitot-static system:
 (a)  Push up and twist the cap to remove it.
 (b)  Turn the oppsite side of the cap up toward the drain.
 (c)  Insert the drain cap into the drain hole in the bottom of the
 drain body.
 (d)  Push the drain cap into the drain body to open the
 spring-loaded seal.  This lets the collected liquid drain.
 (e)  Remove the cap.
 (f)  Turn the opposite side of the drain cap up toward the drain.
 (g)  Push up and twist to lock the cap on the drain body.
 NOTE:____ Turn on the probe heater for 5 minutes when the temperature
 is below 32 degrees F.  Apply heat to the drain line and
 fittings before you drain them, when it is necessary.

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 34-11-01

 ú ú 08.1 Page 206 ú Jul 12/02
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
737-300/400/500MAINTENANCE MANUAL
 PITOT-STATIC SYSTEM - ADJUSTMENT/TEST
_____________________________________
 1.  General_______
 A.  This subject gives two tasks for each pitot-static system. The first task is a full-range leak test. The second task is a low-range leak test. These leak tests pressurize the system or systems that are tested. For each test, you take measurements and compare them to the specifications for the system or systems.
 B.  The full-range leak test makes sure that the pitot-static system does not leak at an altitude of 22,500 feet and an airspeed of 300 knots. You can do a test of each pitot system separtely. You must test all static systems at the same time so that too much differential pressure does not start. During the full-range static system test, the pitot systems must also be pressurized to prevent too much differential pressure.
 C.  You must do the leak test after you flush the pitot-static system, after each major airframe overhaul, or when you remove a fitting. A leak test is not required when you use a quick-disconnect fitting.
 D.  The low-range static system leak test makes sure that the static system does not have leaks at an altitude 5,000 feet above the field elevation.
 E.  You can do the low-range static system leak test to quickly make sure that the static system is operational. A full-range leak test is recommended when there is a leak or the results of the low-range leak test are inconclusive or unsatisfactory.
 F.  You do not have to do a leak test when you connect a quick-disconnect fitting. A visual examination of the quick-disconnect for a complete seal is necessary. You must do a full-range leak test when you cannot make sure that the quick-disconnect has a complete seal.
 G.  These general instructions apply to the pitot-static system leak test.
 (1)  
The rate of the applied vacuum to a static system must be 5000 feet or less for each minute.

 (2)  
The release of the vacuum from a static system must be 5000 feet or less for each minute.

 (3)  
The rate of the applied pressure to a pitot system must be 300 knots or less for each minute.

 (4)  
The release of pressure from a pitot system must be 300 knots or less for each minute.

 (5)  
Absolute pressure in the pitot system must be equal or more than the pressure in the static system.

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