(2)  
Ensure that no deposit or roughness exists in or about the static ports and pitot probe apertures.

(3)  
Perform a leakage test of all systems (Ref 34-11-0 A/T).

3.  Pitot Static System Draining
A.  General
(1)  The pitot static system should be drained periodically per 737 Maintenance Planning Procedure Document, or when airplane has sustained ground exposure to very heavy rainfall, such as monsoonal or tropical thundersquall type rains.
B.  Drain System
(1)  
Locate each drain fitting as shown in Fig. 201. Operate each as described in the following paragraph:

NOTE:  If temperature is below freezing, turn on probe heater for 5 minutes, and if necessary, warm drain line and fittings before draining.

(2)  
Unlock and remove drain cap on lower body of drain by upward pressure and twisting to release cap from the bayonet pins. Invert drain cap and insert the raised, hexagonal shaped portion of cap into opening now exposed in bottom of drain body. Pressing cap into drain body with hand pressure opens a spring-loaded seal and allows any collected liquid in the sump to exit, by gravity flow, from pitot-static system. Remove cap, invert it, and lock it onto base of the drain as it was originally.

5C8 
Feb 20/89  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  34-11-01 Page 205 

PITOT STATIC SYSTEM -ADJUSTMENT/TEST
EFFECTIVITY
GJ B-2524
1.  Pitot Static System Test
A.  General
(1)  
Make sure that the ATC transponders are not in an altitude reporting mode.

WARNING:  MAKE SURE THAT THE ATC TRANSPONDERS ARE NOT IN AN ALTITUDE REPORTING MODE WHEN YOU SIMULATE ALTITUDE. IF YOU DO NOT, YOU CAN ACCIDENTALLY CAUSE FALSE TCAS TARGETS.

(2)  
The low-range leakage test should be performed when a connection in the pitot static system has been broken to permit the replacement of instrument, hoses or tubing. Quick disconnects, when reconnected, do not require a leak check. A visual check of the quick disconnect for full mating and to assure connection is locked and in the sealed position is required. If after an apparent satisfactory low-range test, the behavior of the instruments is still such as to suggest leakage, a full-range test should be performed.

(3)  
The full-range test must be performed after flushing procedure or each major airframe overhaul. Flushing before every system leakage check is not normally required. Both flushing to remove foreign matter and system leakage checks may be carried out at the same time when deemed necessary.

CAUTION:  THE FOLLOWING STEPS ARE REQUIRED TO PREVENT INSTRUMENT DAMAGE, AND TO ENSURE VALID READINGS.

(4)  
Any application or release of vacuum or pressure should be made at a rate of climb or descent less than 5000 feet per minute for the static system and 300 knots per minute for the pitot system. (Appropriate gage saver restrictors should be used.)

(5)  
Pressure in pitot lines should always be greater than, or equal to pressure in static lines. Differential pressure should never exceed 10.00 inches of mercury.

(6)  
The absolute pressure applied to the static system should never exceed the ambient absolute pressure when any instrument is connected to the static system.

(7)  
The captain's, first officer's and alternate static systems must be exposed to the same absolute pressure conditions simultaneously during any leakage test unless otherwise instructed.

B.  Equipment and Materials
(1)  
Dry air pressure source - 0-5 inches of mercury

(2)  
Vacuum source - 0-20 inches of mercury

(3)  
Adapters

(a)  Static Port Test Adapter Assembly - F72823-23, or F72823-40
5C8
May 01/01 34-11-01 Page 501
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.

Pitot Static System Test Connections  5C8 
34-11-01  Figure 501  Feb 20/89 
Page 502 
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 

(b)  Pitot static probe adapter -P/N PSS22300-3-4-4, Allen Aircraft Radio Inc., 2050 Touhy Avenue, Elk Grove Village, Illinois 60007.
(4)  Gages
(a)  
Pitot system gage - 0 to 5 inches of mercury with accuracy of + 0.16 (readable to 士 0.03) inches of mercury or士 5 (readable to 士 1) knots.

(b)  
Static system gage - 0 to 20 inches of mercury with accuracy of 0.10 (readable to士 0.01) inch mercury or士 200 (readable to士 20) feet.

C.  Prepare to Test Pitot Static System
(1)  
The autopilot system should be off during this test.
　
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