N1 speed sensor indication (A320 CEO IAE V2527E)

[Xenal]

We are facing the issue of "ENG 1 OVSPD PROT FAULT" in phase 8 after landing with a failure message of "N1 SENS/HC/EEC1" in phase 6. As we cannot change over the faulty sensor to spare sensor because spare sensor is already unserviceable. The unserviceability is checked by checking the continuity & result is open circuit, therefore, changed over is ruled out. We also replaced FMU but no result. FADEC 1B gave N1L that means the sensor 1B is faulty. For troubleshooting purpose, we swapped EIU 1 with EIU 2 and swapped wiring of 1B to 1A (not an AMM procedure) and fault goes off but as a matter of fact, we suspects that the fault will reappear. Any suggestions and advices from senior members or same finding observed with any other airline, if yes please share your kind experience.

 

[Sparweb]

All of your diagnostic data is telling you the sensor is faulty.
Replace the sensor with a new one. Replace the spare one with a new sensor, too.
For clarity, I'll repeat: if BOTH of your sensors are faulty, then they are useless and both should be replaced.

When seeking advice on maintenance/troubleshooting issues, you should consult the OEM and follow their recommendations. Consulting an open forum on the internet about it is no longer very wise.

 

[WKTaylor]

One note of 'CAUTION' that is universal... especially with multiple 'failing' EE-EL components.

Electrical wiring interconnects between sensor and receiver need to be verified/validated.

I have been involved in numerous situations where electrical components appeared to be faulty or intermittent... only to discover discrepancies in the wires or components....IE: cannon-plugs and/or worn/abraded wires, filthy/damaged/missing connectors/pins [male/female], damaged moisture/oil seals, etc.

In one particularly subtle case an electronic component [black-box] was 'maddingly' intermittent [could not duplicate, CND]. Routine trouble shooting was getting no-where... black box checked-out OK every time. FINALLY an experienced electrician was re-installing the box: just before re-inserting the cannon plug, he pulled-out a flashlight to look inside the female connector of the aircraft wiring... and was shocked to see dirty/scored pin receptacles with metal shavings. The connector was serviced[replaced?] and pins lubricated. It became 'shop practice' to carefully inspect the connectors on the jet wiring... and lubricate the pins [special EE-EL compatible lube] before installing connectors. Ta-Da... that took care of many CND problems.

Regards, Wil Taylor
o Trust - But Verify!
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation, Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", HBA forum]
o Only fools and charlatans know everything and understand everything." -Anton Chekhov

 

[Xenal]

Thanks for your replies. Airbus & IAE suggests that sensors are ok except spare one because when we checked the continuity of Fadec sensor 1A & 1B, both are showing healthy as per TSM. After a break of 1 sortie, the same fault reappeared & the idea of swapping the terminals of FADEC 1A & 1B gives nothing. As per my understanding, something is happening with the wiring & we checked all wiring as per TSM & all found ok. We are just beating about the bush because to remove engine just for speculation of faulty sensor is hell of a thing & operator like us cannot bear that much weight of financial burden. One thing more that why the fault only showing in phase 6 & corelated fault in phase 8. If over speeding of N1 is monitored then why this fault is not coming in different phases of flight. The disturbing fact is, the 1B sensor is showing fault code but when checking resistance, showing perfect i.e. 51 ohms.