1. The symptom is: "Module I is not online".

2, the cause of the malfunction: the aircraft control system has multiple functional modules, the system itself has a strong self-diagnostic function. Maintenance personnel used to reverse the same module location and still reported that "module I was not online". Due to no data, it is difficult to maintain. After being inspected by professional maintenance personnel, each module is an independent single-board extension, which is controlled by a single-chip microcomputer. A single-chip microcomputer and upper computer are online. According to the function of the module and the processing technology analysis, the control mode of each module is different, although some modules The internal hardware is the same, but the control program is different, so the modules cannot be interchanged. After the power-on check, the self-diagnosis function of the control system is operating normally, and the alarm is "Module I is not online", so the module I is specifically checked. There is no abnormality in the internal vision of the module I, the power check CPU operation should be normal, and the status of each integrated circuit is also normal. Viewing the memory as EEPROM, which is characterized by being rewritten at any time, EPROM in the specific operation to be flexible and convenient, but with its reliability is not as high as EPROM, due to some interference, may be mistaken to write, so doubt memory failure.

3, troubleshooting: The memory read out, found that several data are doubtful, disassemble analysis, the program after the start of the self-test test, such as pass, by the host computer alarm. Look at the following control program, some are not like the regular program is not like data. According to the mode analysis of the control program, some control programs have been rewritten so that they cannot pass the self-test. According to the processing technology, the control program is written and verified on the PC, and the self-test can pass. Since the actual writing does not require data writing, the EPROM firmware is rewritten. Power on the machine to check, the module I no longer alarm, the whole machine can operate normally.

Through this example, the maintenance personnel should be able to determine the hardware failure, but also have some knowledge of the control software, and be able to operate the computer.