Air data Computer System Diagram  5C8 
34-12-01  Figure 7  Jun 20/85 
Page 10 
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 

AIR DATA PRESSURE INSTRUMENTS - ADJUSTMENT/TEST
EFFECTIVITY
GJ B-2509 thru B-2510 and B-2524
1.  General
A.  The air data pressure instruments test is performed to operationally check the airplane installation of the DADC (digital air data computer), the air data indicators, and the pneumatic system indicator.
B.  The test is divided into two parts: an operational test and a system test. The operational test is a self-test that uses the BIT (built-in-test) outputs of the DADC to check the system. The system test uses pressure and vacuum sources to check operation and accuracy of the system over a wide range. A leakage test is also included as part of the system test.
2.  Air Data Pressure Instruments Test
A.  General
(1)  The air data pressure instruments operational test is a BIT (built-in-test) test. The test is performed by means of the controls on the front panel of the DADC (digital air data computer). During the test, fixed outputs are sent to the air data instruments for monitoring. The test assures that (1) DADC electronics are functioning properly, (2) the interface and failure warning system between computer and instruments is operating, and
(3) the instruments respond to input signals.
B.  Prepare for test
(1)  
Provide electrical power.

(2)  
Close air data system circuit breakers on load control panels P6 and P18.

NOTE:  All flags disappear upon application of power. When the mach OFF flag disappears, a black mask covers the readout for mach numbers lower than
0.400.
C.  Test air data system
(1)  
Open No. 1 AIR DATA COMPUTER-1 circuit breakers on P18. Verify warning flags on the following captain's instruments drop within 5 seconds.

(a)  
Altimeter

(b)  
VSI Indicator

(c) 
 Mach/Airspeed Indicator
1) Mach
2) Airspeed
3) Vmo

(2)  
Close No. 1 AIR DATA circuit breakers. Verify all warning flags disappear.

Feb 20/89 34-12-01 Page 501
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.

(3)  
Open No. 2 AIR DATA COMPUTER-2 circuit breakers on P6. Verify warning flags on the following F/O's instrument drop within 5 seconds.

(a)  
Altimeter

(b)  
VSI Indicator

(c) 
 Mach/Airspeed Indicator
1) Mach
2) Airspeed
3) Vmo

(4)  
Close No. 2 AIR DATA circuit breaker. Verify all warning flags disappear.

(5)  
Set TEST SELECT switch on DADC to FUNCTION.

(6)  
Depress and hold PUSH TO TEST switch on DADC. Verify TEST VALID WHEN LIT light on DADC comes on in approximately 30 seconds. Then verify following values on the indicators:

(a) 
 Altitude 10,000 士40 feet

(b) 
 Mach 0.785士0.01

(c) 
 Airspeed 440 士2 knots

(7)  
Set TEST SELECT switch to SLEW.

(8)  
Depress and hold PUSH TO TEST switch. Verify TEST VALID WHEN LIT light comes on and VSI indicator slews to -600 士 50 FPM.

(9)  
Set TEST SELECT switch to FAIL WARN.

(10)
Depress and hold PUSH TO TEST switch. Verify TEST VALID WHEN LIT light comes on.

(11)
Remove electrical power if no longer required.

5C8 
34-12-01 Page 502  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  May 01/98 

3.  Air Data Pressure Instruments - System Test
A.  General
(1)  The air data pressure instruments test is performed to check operation and accuracy of the digital air data computers (DADC), the air data instruments and the standby pneumatic altimeter/airspeed indicator.
B.  Equipment and Materials
(1)  
Air pressure and vacuum source, 5 to 40 inches of mercury absolute, and gage for measuring differential pressure, accurate within 士0.010 inches of mercury. Range should be at least 10 inches of mercury.

(2)  
Air pressure and vacuum source, 5 to 30 inches of mercury absolute.

(3)  
Pressure gage accurate to within士0.032 inches of mercury.

(4)  
Stopwatch.

(5)  
Appropriate gage saver restrictors.
　
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