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Check pitot-static system components for physical damage. IF -
NOT OK
NOT OK
NOT OK
NOT OK
OK
Check pitot-static system for leakage. IF -
NOT OK
NOT OK NOT OK OK
Check pitot-static system for restricted air flow by performing flushing procedure. IF -
Pitot-static system is operative.
EFFECTIVITY ALL
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PITOT-STATIC SYSTEM - MAINTENANCE PRACTICES (PRESSURIZATION)
__________________________________________________________
1. General
_______
A. This section provides procedures for pressurizing the four independent pitot-static systems as required to support the performance of a test on any airplane system. The location of all pitot-static connections, tees, and tubing is shown in Fig. 201. On LH 011-030, 054-070, 082-099, AZ 212-299, five tee connectors, to use for connecting test equipment, are installed in the five static systems forward of STA 400 bulkhead on left sidewall (2) and right sidewall (3).
B. Pressurization of a given subsystem is performed per paragraph 2. Paragraphs 2.A., 2.B., and 2.C. apply to all pitot-static systems and must be performed in each case. To complete the pressurization procedure, perform the applicable paragraph from among 2.D., 2.E., 2.F., 2.G., or 2.H.
C. Precautions
(1)
Rate of application or release of vacuum to a static system must be made equivalent to a climb or descent rate of less than 3000 feet per minute. (Use appropriate gage saver restrictions.)
(2)
Any application or release of pressure to a pitot system must be made such that the equivalent rate of change in airspeed is less than 300 knots per minute. (Use appropriate gage saver restrictions.)
(3)
Absolute pressure in the pitot systems MUST NEVER be less than the pressure in the static systems. The difference between pitot and static system pressures must never exceed 10 inches of mercury.
(4)
The absolute pressure applied to any static system MUST NEVER exceed the ambient pressure when any instrument is connected to that static system.
(5)
The captain's, first officer's and alternate static systems must be exposed to the same absolute pressure conditions simultaneously during any pressurization except where test procedure directs otherwise.
(6)
Pitot-static probe heaters must not be activated under any circumstances during tests that require pitot-static probe adapters attached to any pitot-static probe. Place DO NOT OPERATE signs on both probe heater switches whenever adapters are to be used.
(7)
Pitot lines to elevator feel computer and to stabilizer control modules must be disconnected and capped, or a static line must be connected to their static ports, in order that static pressure can be reduced below pitot pressure. Otherwise, damage to elevator feel computer and to stabilizer control modules can occur if pressure in auxiliary pitot system No. 1 and/or No. 2 is decreased below ambient pressure.
(8)
Perform low range leakage test on auxiliary pitot systems No. 1 and 2 after reconnection.
2. Pressurization
______________
A. Referenced Procedures
(1)
21-33-05, Removal/Installation
(2)
27-31-14, Maintenance Practices
EFFECTIVITY
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(3)
27-41-04, Maintenance Practices
(4)
31-31-01, Servicing
B. Equipment and Materials
(1)
Pneumatic Test Set
(a)
Dry air pressure source (1 required), 30 to 40 inches of mercury (absolute)
(b)
Vacuum sources (2 required), 4 to 30 inches of mercury (absolute)
(2)
Adapters
(a)
One flush static port adapter for alternate static system (surface contact only; must not make metallic contact with port) - F72823-23 or equivalent
(b)
Two pitot-static system probe adapters - 884EE or equivalent
(c)
If the option of connecting pneumatic test set to drain or test connector in main electronic equipment center is chosen, mating connector from Airborne Research, Sun Valley, California, is required. Part number 40007-B46 mates with male connector on static system drain or test connector.
(3) 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：747飞机维护手册AMM CHAPTER 34 - NAVIGATION 第34章导航1(24)
