(a)  
Remove external hoses and static port seals, ensuring that no deposit or roughness exists in or about static ports.

(b)  
Ensure that flight recorder (if installed) is returned to normal operating configuration.

(c)  
If no longer required, remove electrical power from airplane.

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34-12-0 Page 510  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  Jun 20/90 

AIR DATA PRESSURE INSTRUMENTS - DESCRIPTION AND OPERATION
EFFECTIVITY
GJ B-2509 thru B-2510 and B-2524
1.  General
A.  Air data pressure instruments are those which derive their inputs from the pitot static air pressure system and the air data computer system (Ref 34-11-0, Pitot Static System). The air data pressure instruments are two airspeed/mach indicators, two vertical speed indicators, two altimeters, and two air data computers. A combined pneumatic altimeter and airspeed indicator is also provided for standby indication.
B.  Computed airspeed and mach number are displayed on mach/airspeed combined instrument indicators from air data computer processed pitot static air pressure data. The indicators accept inputs of corrected altitude and airspeed from the air data computers for controlling the maximum operating airspeed pointer of the mach/airspeed indicators. The indicators also provide a signal to the mach airspeed warning system to actuate an aural warning when maximum operating airspeed is exceeded. A standby airspeed indicator on the captain's instrument panel operates conventionally from direct static pressure information.
C.  Vertical speed or rate-of-climb indicators, through a range of 0 to 6000 feet per minute, are operated by corrected altitude rate signals from the air data computers.
D.  Altitude information, derived from static pressure signals computed and corrected in the air data computers, is shown on the electric altimeters. A standby altimeter on the captain's instrument panel operates conventionally from direct static pressure information.
E.  Air data computer No. 1 electrically integrates and computes from pitot static pressures, the corrected altitude, mach number, and airspeed signals. This data is sent to the captain's air data instruments, autopilot, flight director, mach trim, and other systems shown on Fig. 7. Power to operate the computer is obtained from circuit breaker panel P18. Air data computer No. 2 also provides corrected altitude and airspeed signals. This data is sent to first officer's air data instruments and other systems shown on Fig. 7.
2.  Mach/Airspeed Indicators
A.  The mach/airspeed indicator is a combination of two flight instruments presenting an integrated display of computed airspeed and mach number. The pilots are each provided with an indicator. The air data system is designed to utilize a combined instrument in which the altitude assembly, the airspeed assembly and the mach number assembly are operated from air data computer processed information.
Feb 20/89 34-12-01 Page 1
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.

K84711
 Mach/Airspeed Indicator  567 
34-12-01  Figure 2  Aug 15/80 
Page 2 
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 

B.  Computed airspeed derived from the air data computer, which corrected for static pressure source error, drives the airspeed pointer from 60-thru 450-knot range of airspeed. The mechanism produces linear rotation of the pointer in five knot calibration increments between 60 and 100 knots, in two knot calibration increments between 100 and 160 knots, and logarithmically in 10-knot increments between 160 and 450 knots (Fig. 2). An airspeed valid signal from the air data computer is also provided to the A/S flag.
C.  Mach number indication is presented on a two drum digital readout through the range .40 to .99 mach. Below .40 mach the readout is covered by a mach flag. The indicator computes mach from inputs of airspeed and altitude signals processed by the air data computer. Upon power failure, or loss of 28 volts dc from the air data computer a striped red and white OFF flag will appear to cover the digital mach readout.
D.  The colored pointer on the indicator shows maximum operating speed of the airplane as a function of corrected altitude and airspeed from the air data computer. The speed reference marker (target bug) is electrically fed from the performance data computer. The "INOP" flag indicates the absence of an operational performance data computer system and the target bug will store at 440 knots. Pulling the bug set knob out will place the target bug in manual mode and will retract"INOP" flag. When operating in the manual mode, a "M" flag will appear in view at top of indicator. White peripheral pointers may be set manually to any desired airspeeds.
　
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