速度配平失效代码SR答复
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前段时间遇到一个速度配平失效的故障——速度配平到底因何失效（点击链接即可阅读），后续更换了PSEU，至今飞机状态正常。
针对自检出现的几个代码：
个人认为是虚假代码，并询问了波音，以下是波音的回复内容：
RESPONSE:
Boeing thanks XXX for reporting the event and providing the maintenance findings. The provided information has been reviewed. Please see the Boeing responses and recommendations below.
The presence of DFCS BITE fault history maintenance messages (MM) 22-11173 suggest that FCC-A was receiving incorrect stabilizer trim position data from the M1192 stabilizer position sensor-A during the DFCS BITE 60.32 ground test.
Maintenance recommendations for MM 22-11173:
a)Check all wiring, terminal blocks and connectors shown in the attached WDM 22-12-31 page for any problems. Repair any problems, if found. Report any problems found to Boeing.
b)Replace the M1192 stabilizer position sensor-A, as precautionary.
The presence of DFCS BITE fault history maintenance message (MM) 22-11125 suggests that FCC-A was receiving incorrect position data from the M929 elevator position sensor. However, this problem should not cause the Speed Trim Fail light to illuminate. Instead, this fault can cause the NO AUTOLAND message to show and could also cause the autopilot not to work. Based on the information provided, we do not know if there was an autopilot engagement problem.
Maintenance recommendations for MM 22-11125:
a)Check all wiring, terminal blocks and connectors shown in the attached WDM 22-12-31 page for any problems. Repair any problems, if found. Report any problems found to Boeing.
b)Replace the M929 elevator position sensor, as precautionary. The presence of DFCS BITE fault history maintenance message (MM) 22-11126 suggests that FCC-B was receiving incorrect position data from the M929 elevator position sensor. However, this problem should not cause the Speed Trim Fail light to illuminate. Instead, this fault can cause the NO AUTOLAND message to show and could also cause the autopilot not to work. Based on the information provided, we do not know if there was an autopilot engagement problem.
Maintenance recommendations for MM 22-11126:
a)Check all wiring, terminal blocks and connectors shown in the attached WDM 22-12-41 page for any problems. Repair any problems, if found. Report any problems found to Boeing.
b)Replace the M929 elevator position sensor, as precautionary.
In addition to all the wiring checking good, then there may be a chafed or cut wire in the wiring bundles that only presents itself during flight. Along with continuity checks, Boeing recommends a visual inspection of all related connectors for bent or improperly seated contacts as well as checking for FOD (Foreign Object Damage), contamination, corrosion, or other obvious damage in connectors. Also check for shorts to ground, shorts to shields, and shorts to other pins. Perform a hand over hand visual inspection of the wire routing looking for evidence of chaffing or pinched wires in clamping. Perform pull checks on wiring in connectors and splices to verify the crimps are good. When performing continuity tests for intermittent connections Boeing recommends utilizing an analog meter, having one person monitor the meter for ground/short with a second person manually manipulating the wire routing checking for intermittent connections (shake test).
The 'SPEED TRIM FAIL' light can be illuminated when the autopilot is not engaged and the airplane is operating in an envelope where speed trim functionality is active and the FCC in charge of speed trim is unable to command the stab trim motor to move. For speed trim, only one FCC is active and providing the functionality; if that FCC is unable to provide speed trim functionality, it will release control of this function and the other (backup) FCC will resume speed trim. If the other/backup FCC can resume speed trim with no issues in the flight, then the SPEED TRIM FAIL light will not illuminate in the air but should illuminate upon landing/master caution recall.
The FCC speed trim system requires these interfaces, intermittent problems with any of these interfaces below can cause the speed trim fail light to illuminate. Make sure all of these interfaces are working normally.
-FCC (A/B)
-Air Data/Inertial Reference Unit (ADIRU L/R)
-Stab Position Sensors (M1192/M1193)
-DEU 1/2 (for engine N1)
-PSEU, M2061 (for squat switch indication)
-Flight Controls Overhead P5 Panel
-Integrated Flight Systems Accessory Unit, M1474 (IFSAU)
-Airplane 28V Power primary input to FCC (from airplane 28VDC bus 1 section 1 power source C/B C1045, or from airplane 28VDC bus 2 section 2 power source C/B C1046) - see WDM 22-11-11
-Airplane 28V Power battery input to FCC (from airplane 28VDC switch hot battery bus C/B C1049, or from airplane 28VDC switch hot battery bus C/B C374) - see WDM 22-14-11
-Wiring
个人觉得波音的SR参考意义不太大，大家觉得呢？
之前也有朋友留言说DFCS自检时碰到驾驶盘就会出升降舵位置传感器的代码，这个已经确认过，当时自检不止一次，并未碰过驾驶盘。
还是等PSEU的修理报告看吧。
／End.