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The ground test executive routine turns on the GRD TEST lightswitch and removes existing display message during initialization. The ground test executive routine calls up a ground-test engagement check routine which generates analog ground-test command discretes to all the FCCs and the TMC. During the ground-test engagement check routine, the message 00 SYST ENG VFY// IN PROGRESS is displayed. There is a two second delay after the ground test command is sent. This allows the computers to initialize into their ground-test modes and send ground-test data to the MCDP. The ground test command routine verifies each computer for a correct ground-test engagement response by checking bits 25, 26, 29, and 32 of word one of label 356 data block.Each of the four computers does the following tests upon receiving the analog ground test discrete bit. They check the AIR/GRD sensors for an on-ground condition and if on-ground, sets TEST REQUEST WRAP-AROUND bit 29 to one. A valid response from the computer sets the ARINC INPUT ERROR flag to zero and TEST REQUEST WRAP-AROUND bit 29 to one. An invalid response from the computer causes the MCDP to display a fault message. The fault message is determined by the status of the ARINC INPUT ERROR flag and digital discrete bits 25, 26, 29, and 32. Refer to GROUND TEST ENGAGE FAULT MESSAGE MATRIX graph (Fig. 10) for details.After the completion of the engagement check, the ground-test executive routine calls up the computer self-test routine. While this routine is run, the message 00 COMP TEST// IN PROGRESS is displayed. The computer self-test routine commands computers that passed the engagement check, to execute their built-in self-tests. Two test commands are sent to the FCC's. The first initiates the FCC self-test and the other initiates an interface check between the FCC and its sensors. The TMC has three test commands sent to it. The first test initiates the TMC self-test, the second initiates interface checks between the TMC and its sensor. The third test initiates an interface check between the TMC and the autothrottle servomotor generator. The MCDP computer self-test routine checks the response data from each computer's AIM word label 356. Word one must contain the test routine number (bits 17-24). Word two must have test valid (bit 29) set to one. Self-tests are automatically terminated after five seconds.
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 5)  The completion of computer self-tests causes the microprocessor to collect and store word label 357 fault data for later use during ground testing. The label 357 word format is in an eight word block. Word one contains the number of words to follow. Words two through eight contain the discrete interface data with 21 discretes per word.
 6)  The interface faults are displayed by the MCDP according to the GROUND TEST ENGAGE FAULT MESSAGE MATRIX (Ref Fig. 10). During the self-test routine, the MCDP displays the messge 00 INFO DATA IN// IN PROGRESS. After all interface data has been stored and associated fault data messages displayed, the ground test routine transfers control of the microprocessor to the test select routine. The transfer is indicated when 01 FCC TEST? is displayed.
 (c) Test Selection Process
 1)  The operator selects the desired test from the list on the instruction panel by pressing the UP or DOWN ground test select switches (incremental or fast slewing). The NO/SKIP switch increments the test selections up. During the selection routine, each test is displayed with a question mark. The operator presses the YES/ADV switch to engage the test displayed. The engaged test causes the test select routine to display any required computers that failed the ground entry checks and display interface faults for the functioning computers.
 2)  If at least one of the required computers and its interface is valid, the test number select routine for the front panel test is called. This loads the test routine number and test parameters into the MCDP output data block. The data block is transmitted to the test computer on the ARINC 429 data bus. The test computer responds by setting the test routine number in progress bit, and system status bits in word 356 (Ref to Fig. 12, MCDP Input Test Data Block).
 (13) Ground Test Engage Fault Message Matrix (Fig. 13)
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