S 864-054
(2)
Make sure that the airplane is not on jacks and the engines are off.
S 974-017
(3)
Use a plumb bob or use CMCS input monitoring to find the pitch attitude of the airplane:
(a) Do this to use a plumb bob:
1) Hang a plumb bob in the wheel well of the right body gear and read the pitch attitude (AMM 08-00-00/201).
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747-400 MAINTENANCE MANUAL
(b) Do this to use input monitoring to find the pitch attitude: 1) Make sure the IRS is in the NAV mode. 2) Select OTHER FUNCTIONS from page 2 of the CMC MENU. 3) Select INPUT MONITORING from the other functions menu. 4) Use the CDU keypad to type this: E/80/324/00 5) Push the top left key on the CDU to start input
monitoring.
NOTE:____Three samples show on the display. Each sample is two lines of 1's and 0's. Bit 32 is the left bit of the first line. Bit 1 is the right bit of the second line.
6) Make a record of bits 29 through 15.
NOTE: Bit 29 is the sign bit; 0 is + (positive), 1 is -
____ (negative). Bits 28 through 15 are the data bits. Bit 28 is the most significant bit.
7) Convert bits 28 through 15 from binary to decimal and then multiply by .011 to get the pitch attitude.
NOTE: The result should be between -5 and +5 degrees.
____
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(4) Use WBC mode 32 to put the pitch attitude into the new PAS:
(a)
Open the keyboard cover of the WBC.
(b)
Push the MODE key.
(c)
Push the 3 key and then the 2 key.
(d)
Push the ENTER key.
(e)
When OK? shows, push the YES key.
(f)
When PAS DEG shows, put in the pitch attitude (include the sign, + or -). 1) Use these keys to put in data: + - . 0-9 2) Use the left arrow to erase incorrect data.
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(g) When the correct pitch attitude shows, push the ENTER key.
NOTE: If the pitch attitude is not between -5 and +5 degrees,
____ then INVALID ATTITUDE shows.
(h) When OK? shows, make sure the value is correct and then push the YES key. (The WBC then shows PROCESS COMPLETE for approximately 8 seconds.)
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(5) Use WBC mode 27 to find the PAS zero value for the new PAS:
(a)
Push the MODE key.
(b)
Push the 2 key and then the 7 key.
(c)
Push the ENTER key.
(d)
When OK? shows, push the YES key.
(e)
When ZERO PAS shows, make a record of the value that shows.
(f)
Push the RESET key to stop mode 27. (The WBC then shows PROCESS ABORTED for approximately 8 seconds.)
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(6) Change the written record of calibration data for the airplane to show the new PAS zero value.
F. Pitch Attitude Sensor Installation Test
S 744-055
(1) Use WBC mode 04 to show the pitch attitude calculated by the PAS:
(a)
Push the MODE key.
(b)
Push the 0 key and then the 4 key.
(c)
Push the ENTER key.
(d)
When OK? shows, push the YES key.
(e)
When PAS shows, make sure the value that shows is approximately the same as the value you put in with mode 32.
(f)
Push the RESET key to stop mode 04. (The WBC then shows PROCESS ABORTED for approximately 8 seconds.)
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(2) Remove the electrical power if it is not necessary
(AMM 24-22-00/201).
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