某CFM56-5B发动机,远程监控在巡航阶段触发以上监控故障,下面我们针对此故障信息进行分析。
【故障白话】
ECAM警告:[ENG 1 FADEC B FAULT],只表明:1发FADEC,B通道上有故障,至于什么故障并不知晓。
CFDS信息:[ECU (X CHANNEL) ENG1A],单单这条信息,我请教了多位工程师,大家的理解也不一致。直译为:1发ECU,A通道上(X 通道);这儿X CHANNEL有人理解为交输通道;不管怎么理解?不影响我们对故障的判断。因为ECU的两个通道是物理集合在一起的。我们权当是:1发ECU,A通道报了故障。但这个故障不知是A通道自己出了问题,还是A通道探测到B通道出了问题,反正A通道就报出来有问题。这就好比两个人打架吵嘴一样,一般谁都不会说自己的过错,都会一直强调对方的过错。这个地方我们是否可理解为:B通道本身出问题了,它不能说话了或者说的话没人相信了;而A通道本身是好的,只是探测到B通道出问题了,报了故障。不管怎样?反正是1发ECU出了问题。那既然是1发ECU出问题了,是不是就换掉了事。那也是不行的。虽然我们初步推断ECU出问题了,那到底是ECU本身的问题?还是ECU供电出了问题?亦或其他问题?我们需要具体分析。
【系统简介】
全权数字发动机控制(FADEC)系统控制发动机。每台发动机的FADEC系统由一个双通道电子控制单元(ECU)及其相关外围设备组成。FADEC系统是完全冗余的,围绕两个独立的ECU控制通道构建。双输入、双输出和从一个通道自动切换到另一个通道,消除了任何休眠故障。ECU由两个通道(A和B)组成。每个通道都可以控制发动机系统的不同部件。通道A和B永久运行。控制中的通道管理系统。FADEC系统的所有控制输入都是双重的。只有一些用于监测和指示的次要参数是单一的。为了提高容错设计,通过交输通道数据链在两个控制通道(ECU内部)之间交换参数。每个通道也可以独立运行,无需交输通道数据链。
正常情况下,发动机未运转时,ECU通过EIU由飞机系统供电。当发动机运转,N2>15%时,每个ECU由三相永磁交流发电机(PMA)供电。FADEC控制交流发电机PMA为两个ECU通道提供独立电源。【故障分析】
在本案例中,我们初步推断了是1发ECU故障,但不知是ECU本身故障还是供电故障。
由于该故障是发生在巡航阶段,发动机是正常运转的,N2>15%是肯定成立的,通过前面的介绍,这时ECU的供电来自PMA。
到此,我们基本就划定了一定的范围:也就是PMA至ECU之间,包括PMA、ECU以及之间的线路。
【程序解析】
根据监控信息[ENG 1 FADEC B FAULT]+[ECU (X CHANNEL) ENG1A]我们定位至:Loss of the ECU Cross Channel on Engine 1 - Channel B-Accessory Gearbox Assembly解析:根据我们上面的分析,故障的原因有可能是:PMA、ECU和之间的线路。这个地方提到了附件齿轮箱组件,因为PMA是直接安装在附件齿轮箱上的,如果因为PMA转子和定子相磨金属屑进入附件齿轮箱,附件齿轮箱也是需要拆下维护的,所有也属于故障源之一。
A.Referenced Information
SUBTASK 77-10-00-710-130-AA.Do the operational test of the FADEC 1A on the ground (with engine non motoring) Ref. AMM 73-29-00-710-040.4.Fault Isolation
SUBTASK 77-10-00-810-095-AA.If the failure message ECU (A CHANNEL) is not confirmed:-no maintenance action is required.NOTE:This failure message is generated when there is an internal ECU cross channel fault, control alternator stator contact, or related wiring.解析:如果故障信息ECU (A CHANNEL)没有确认:无需维护。注:当有一个ECU内部交输通道故障、控制交流发电机定子接触,或相关的线路出现时,这个故障触发。这是FWC故障触发原理设定好,也就是说,如果是ECU本身问题,最可能得是ECU内部交输通道问题。
SUBTASK 77-10-00-810-118-BB.If the failure message ECU (A CHANNEL) is not confirmed but is repetitive:
-do a check of the J10 harness connection at the control alternator:
(1)If the connection is loose:
-tighten the connection by hand plus one eighth of a turn.
NOTE:Soft nose pliers may be used if necessary.
(2)If the connection is tight:
-Disconnect the J10 harness from the alternator stator.
(a)Visually examine the alternator stator receptacle and the J10 harness connector for damaged pins or contamination, and the 90° elbow of the harness boot for evidence of overheat Ref. AMM 73-21-50-210-002.
1.If harness or alternator stator connector is damaged:
-repair or replace as required.
2.If no damage is found:
-remove the Alternator Stator Ref. AMM 73-21-30-000-001.
-visually examine the alternator stator and rotor for evidence of contact.
a.If evidence of contact is found, the cause must be determined:
-inspect the alternator rotor nut for proper installation, inspect the Electrical Master Chip Detector for particles Ref. AMM 79-00-00-281-002.
* If chips are found on the chip detector:
- replace the Accessory Gearbox Assembly Ref. AMM 72-63-00-000-003 and Ref. AMM 72-63-00-400-003
* If rubbing is found and chips were not found on the chip detector:
- replace the Alternator Rotor and stator Ref. AMM 73-21-30-000-001 and Ref. AMM 73-21-30-400-001.
* If no rubbing is noted:
- reinstall the alternator stator Ref. AMM 73-21-30-400-001.
b.If no evidence of contact is found:
-replace the J10 Harness Ref. AMM 73-21-50-000-043 and Ref. AMM 73-21-50-400-043
(3)If fault continues during the subsequent flights:
-replace the ECU (4000KS) Ref. AMM 73-21-60-000-001 and Ref. AMM 73-21-60-400-001.
解析:子步骤B:如果故障信息ECU(A CHANNEL)未被确认,但重复出现:
这时,我们考虑间隙性故障可能性大。
按照常规,先检查接头;如果接头松动,拧紧;如果插头是拧紧状态,断开插头检查插钉;如有有损坏,修理;如果没损坏,检查PMA内部,转子和定子;如果转子和定子相磨,检查磨损程度,如果金属屑进入附件齿轮箱,更换附件齿轮箱和PMA;如果磨损但金属屑没有进入附件齿轮箱,更换PMA;如果没有磨损;更换线束。如果故障继续,更换ECU。
SUBTASK 77-10-00-810-119-BC.If the failure message ECU (A CHANNEL) is confirmed:-do a check of the J10 harness connection at the control alternator:(1)If the connection is loose:-tighten the connection by hand plus one eighth of a turn.NOTE:Soft nose pliers may be used if necessary.(2)If the connection is tight:-disconnect the J10 harness from the alternator stator (ALT-A) (located in the left core compartment).(a)Visually examine the alternator stator receptacle and the J10 harness connector for damaged pins or contamination Ref. AMM 73-21-50-210-002.1.If harness or alternator stator connector is damaged:-repair or replace as required.-do an electrical resistance test through the alternator stator connector between:. pins 5 and the ground (>10 Megohms)3.If the resistance values are out of the specified limits:-replace the alternator stator Ref. AMM 73-21-30-000-001 and Ref. AMM 73-21-30-400-001.4.If the resistance values are in the specified limits:-reconnect the J10 harness to the alternator stator.-disconnect the J10 harness from the ECU (4000KS) receptacle.-Visually examine the ECU (4000KS) receptacle and the J10 harness connector for damaged pins or contamination Ref. AMM 73-21-50-210-002.a.If harness connector or ECU receptacle is damaged:-repair or replace as required.-do an electrical resistance test through the J10 harness between:. pins 5 and 4 (>10 megohms). pins 13 and 4 (>10 megohms). pins 14 and 4 (>10 megohms). pins 15 and 4 (>10 megohms). pin 5 and the ground (>10 megohms)* If the resistance values are out of the specified limits:- replace the J10 harness Ref. AMM 73-21-50-000-043 and Ref. AMM 73-21-50-400-043.* If the resistance values are in the specified limits:- replace the ECU (4000KS) Ref. AMM 73-21-60-000-001 and Ref. AMM 73-21-60-400-001.解析:子步骤C:如果故障信息ECU(A CHANNEL)被确认:
这时,我们考虑显性稳定故障可能性大。
按照常规:检查线束接头,如果松动,拧紧;如果是紧固的,断开插头检查插钉;如果有损伤修复;如果没损伤,测量PMA定子阻值,如阻值超限,更换定子;如果在范围内,断开线束两端检查,如果有损伤,修复;如果没损伤,测量线路阻值,如超限,更换线束;如正常,更换ECU。
SUBTASK 77-10-00-710-131-AD.Do the test given in Para. 3.A.(1)No additional maintenance action is required if the fault is not confirmed.(2)Repeat the fault isolation procedure if the fault continues.
【故障总结】
根据本案例的监控信息,和地面测试报告以及储存报告,结合排故实际,我们给出大体的推论:本次案例原因是:飞机在巡航阶段,1发ECU,B通道交输数据链处理器故障所致,系ECU本身的故障。【排故方案】
[ENG 1 FADEC A FAULT]+[ECU (X CHANNEL) ENG1B]
[ENG 1 FADEC B FAULT]+[ECU (X CHANNEL) ENG1A]
[ENG 2 FADEC A FAULT]+[ECU (X CHANNEL) ENG2B]
[ENG 2 FADEC B FAULT]+[ECU (X CHANNEL) ENG2A]
参照TSM77-10-00-810-***-A排故;
地面做(发动机非运转)的FADEC的测试;
对J9或J10线束及接头做详细目视检查;
对交流发电机PMA定子接头进行电阻测试;
对J9或J10线束进行线路测量;
完成EMCD检查;
装机ECU硬件件号、软件件号、版本号确认;并预防性更换ECU;
完成FADEC测试;
同一个故障现象对应的故障原因可能多种多样,即使空客的TSM手册也无法囊括所有,况且TSM手册也只是从原理分析、结合案例的一种大概率事件顺序排布,还在持续完善中。所以,我们在排故时,即使表面看上去故障指向挺明确的故障,我们还是要排除掉其他的小可能性,才能把最可能的因素作为我们排故的故障源。