经过一位朋友的提醒,纠正之前关于发动机 wrap fault 的说明错误。
参考资料:
CFM56-7B TRAINING MANUAL
FAULT DETECTION & ANNUNCIATION
CTC-219 Level 4
注意一定要 Level 4 的才有,Level 3 里没有 wrap fault 的相关说明。
↑ Level 3 里面没有
以下是手册里的详细说明:
Wraparound
The EEC uses a current-driver-wraparound test to check correct operation of the torque motors, solenoid drivers,output databuses and certain relays.
To check the integrity of the circuits, the EEC outputs a calculated current and compares it to the sensed return current (wraparound).
To check the integrity of the circuits, the EEC outputs a calculated current and compares it to the sensed return current (wraparound).
Control current out-of-range
The EEC checks the integrity of the FMV, VSV, VBV,HPTA CC, LPTA CC and TBV torque-motor and solenoid circuits, using the current-driver-wraparound test.
If there is a difference between the output and return current, it must exceed a defined value for a specific time interval in order for a fault to be declared.
If this kind of fault is declared, a ‘CONTROL CURRENT IS OUT OF RANGE’ message is generated.
On a transition of channel selection state from standby to active, the EEC clears all wraparound faults and sets the fault-delay timers to zero.
↑ 手册里还列举了3种故障情况
Demand and position signals disagree
The EEC checks if the sensed (measured) actuator position agrees with the demanded position.
A fault message is generated if :
- The absolute value of the difference between the demand and valid position is greater than 5%.
and,
- There is not a wrap fault on the local channel.
and,
- N2 is greater that 3181 rpm (22% N2).
and,
- The channel is active.
and,
- The fault persists for more that 4.8 seconds (11.5 seconds for HPTA CC).
↑ 图中与TM相连的红色线路部分
VBV和VSV类似:
总结如下:
LPTACC, HPTACC, TBV,VBV,VSV,FMV,是通过HMU里的EHSV(electro-hydraulic servo valve)来进行控制的。EEC 通过TM(torque-motor)电流输入来控制EHSV,并且只有当前控制通道才会提供输入,另一个备用通道输入是断开的。
EEC监控TM的输入和输出电流,正常情况下输入和输出电流是相同的。如果输入和输出差异达到设定值且持续一定时间,EEC将设置一个wrap故障。
所以,wrap故障EEC记录的代码为Control Current Out of Range,通常是到EHSV的控制输入线路故障或者EHSV电气故障。
wrap故障监控的是输入控制电路,而不是反馈电路,HMU里 EHSV 反馈电路的故障通常是 Demand and Position Signals Disagree。而另一个Position Signal is Out of Range 故障,指的是LPTACCV, HPTACCV, TBV,VBV,VSV,FMV 的位置反馈信号。
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