A maintenance controller realizes later he mistakenly deferred an N-1 vib indication on an airbus A3...

Attributes
ACN	801728
Time
Date	200806
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : zzz.airport
State Reference	US
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	A320
Operating Under FAR Part	Part 121
Flight Phase	ground : maintenance
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	other personnel other
ASRS Report	801728
Events
Anomaly	aircraft equipment problem : critical maintenance problem : improper documentation non adherence : far non adherence : published procedure
Independent Detector	other other : 1
Resolutory Action	none taken : detected after the fact
Consequence	other
Factors
Maintenance	contributing factor : briefing performance deficiency : non compliance with legal requirements performance deficiency : fault isolation performance deficiency : logbook entry
Supplementary
Problem Areas	Aircraft Maintenance Human Performance
Primary Problem	Maintenance Human Performance

Narrative:

Aircraft aborted takeoff with a momentary vibration system fault. Crew called maintenance control. I looked at postflt report and fault message was 'engine 1 speed sensor 4000EV.' crew reported did not feel any vibration. Fault message is a class 2 fault and deferred per MEL 77-00 N1 vibration indication. This was incorrect and changed it to 71-71 evmu fault. That being said; going back and auditing my deferrals; I noticed this was an upper ECAM message which is a class 1 fault. I stopped the aircraft as soon as I realized the mistake. ZZZ1 maintenance found a bad N1 sensor in the engine for the evmu. As a footnote: workload is very heavy due to crew write-ups and refusals. Need to find out from iae and airbus why this was a class 1 fault. The clear language message 'engine 1 speed sensor 4000EV is a class 2 fault.' we have had many problems with this pickup and has not resulted in an upper ECAM message. Callback conversation with reporter revealed the following information: reporter stated the airbus iae V2500 engine has vibration pickup monitoring unit that is very sensitive to vibration noise and heat. This has been causing lower ECAM fault messages displays which are a class-2 fault and deferrable. Only one of the two (evmu) can be deferred. Reporter stated that normally the upper ECAM message for evmu faults would only appear when both engines evmu's failed. So he mistakenly assumed the single fault was displayed on the lower ECAM; which was not correct. An upper ECAM fault for a single engine evmu fault was unusual. Reporter stated that at times when maintenance applies a 'global reset' of the airbus electrical power (shut down everything); including the battery; for four minutes; and then powers back up; the vibration fault goes away without any further problems. The engine has to be removed to replace the evmu on the V2500 engine.

Original NASA ASRS Text

Title: A MAINT CONTROLLER REALIZES LATER HE MISTAKENLY DEFERRED AN N-1 VIB INDICATION ON AN AIRBUS A320 AS A CLASS-2 FAULT. VIBRATION MESSAGE WAS ACTUALLY ON UPPER ECAM AS A CLASS-1 FAULT.

Narrative: ACFT ABORTED TKOF WITH A MOMENTARY VIBRATION SYS FAULT. CREW CALLED MAINT CTL. I LOOKED AT POSTFLT RPT AND FAULT MESSAGE WAS 'ENG 1 SPD SENSOR 4000EV.' CREW RPTED DID NOT FEEL ANY VIBRATION. FAULT MESSAGE IS A CLASS 2 FAULT AND DEFERRED PER MEL 77-00 N1 VIBRATION INDICATION. THIS WAS INCORRECT AND CHANGED IT TO 71-71 EVMU FAULT. THAT BEING SAID; GOING BACK AND AUDITING MY DEFERRALS; I NOTICED THIS WAS AN UPPER ECAM MESSAGE WHICH IS A CLASS 1 FAULT. I STOPPED THE ACFT AS SOON AS I REALIZED THE MISTAKE. ZZZ1 MAINT FOUND A BAD N1 SENSOR IN THE ENG FOR THE EVMU. AS A FOOTNOTE: WORKLOAD IS VERY HVY DUE TO CREW WRITE-UPS AND REFUSALS. NEED TO FIND OUT FROM IAE AND AIRBUS WHY THIS WAS A CLASS 1 FAULT. THE CLR LANGUAGE MESSAGE 'ENG 1 SPD SENSOR 4000EV IS A CLASS 2 FAULT.' WE HAVE HAD MANY PROBS WITH THIS PICKUP AND HAS NOT RESULTED IN AN UPPER ECAM MESSAGE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: REPORTER STATED THE AIRBUS IAE V2500 ENGINE HAS VIBRATION PICKUP MONITORING UNIT THAT IS VERY SENSITIVE TO VIBRATION NOISE AND HEAT. THIS HAS BEEN CAUSING LOWER ECAM FAULT MESSAGES DISPLAYS WHICH ARE A CLASS-2 FAULT AND DEFERRABLE. ONLY ONE OF THE TWO (EVMU) CAN BE DEFERRED. REPORTER STATED THAT NORMALLY THE UPPER ECAM MESSAGE FOR EVMU FAULTS WOULD ONLY APPEAR WHEN BOTH ENGINES EVMU'S FAILED. SO HE MISTAKENLY ASSUMED THE SINGLE FAULT WAS DISPLAYED ON THE LOWER ECAM; WHICH WAS NOT CORRECT. AN UPPER ECAM FAULT FOR A SINGLE ENGINE EVMU FAULT WAS UNUSUAL. REPORTER STATED THAT AT TIMES WHEN MAINT APPLIES A 'GLOBAL RESET' OF THE AIRBUS ELECTRICAL POWER (SHUT DOWN EVERYTHING); INCLUDING THE BATTERY; FOR FOUR MINUTES; AND THEN POWERS BACK UP; THE VIBRATION FAULT GOES AWAY WITHOUT ANY FURTHER PROBLEMS. THE ENGINE HAS TO BE REMOVED TO REPLACE THE EVMU ON THE V2500 ENGINE.

Data retrieved from NASA's ASRS site as of May 2009 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

A maintenance controller realizes later he mistakenly deferred an N-1 vib indication on an airbus A320 as a class-2 fault. Vibration message was actually on upper ECAM as a class-1 fault.