A line mechanic reports he mistakenly deactivated #2 engine anti-ice valve according to MEL 30-27-01...

Attributes
ACN	1003777
Time
Date	201204
Local Time Of Day	0601-1200
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Light	Daylight
Aircraft 1
Make Model Name	A320
Operating Under FAR Part	Part 121
Flight Phase	Parked
Flight Plan	IFR
Component
Aircraft Component	Pneumatic Control Valves
Person 1
Function	Technician
Qualification	Maintenance Powerplant Maintenance Airframe
Events
Anomaly	Aircraft Equipment Problem Critical Deviation - Procedural Published Material / Policy Deviation - Procedural MEL Deviation - Procedural FAR

Narrative:

I troubleshot a #2 engine anti-ice valve discrepancy on an A320 aircraft. I reactivated the valve for troubleshooting and determined that there was good voltage to the valve. I manually actuated the valve and noticed a sticking in the 'closed' position and determined the valve was bad. We did not have a valve in stock so I was told to defer the discrepancy. I mistakenly deactivated the valve according to MEL 30-27-01A instead of MEL 30-27-01D. At this point in time I do not know how I made this error. My only thought is that due to poor lighting in the cockpit I mistook the 'D' for an 'a'. Aircrew noticed improper anti-ice valve indication on engine start. I did not thoroughly review which MEL had been applied to the aircraft. Proper MEL was applied [after a] gate turnback. Suggest [I] thoroughly review and make sure I understand which MEL has been applied to the aircraft.

Original NASA ASRS Text

Title: A Line Mechanic reports he mistakenly deactivated #2 engine anti-ice valve according to MEL 30-27-01A; instead of MEL 30-27-01A. Flight crew returned the A320 aircraft to gate after noticing improper anti-ice valve indication during engine start.

Narrative: I troubleshot a #2 engine anti-ice valve discrepancy on an A320 aircraft. I reactivated the valve for troubleshooting and determined that there was good voltage to the valve. I manually actuated the valve and noticed a sticking in the 'Closed' position and determined the valve was bad. We did not have a valve in stock so I was told to defer the discrepancy. I mistakenly deactivated the valve according to MEL 30-27-01A instead of MEL 30-27-01D. At this point in time I do not know how I made this error. My only thought is that due to poor lighting in the cockpit I mistook the 'D' for an 'A'. Aircrew noticed improper anti-ice valve indication on engine start. I did not thoroughly review which MEL had been applied to the aircraft. Proper MEL was applied [after a] gate turnback. Suggest [I] thoroughly review and make sure I understand which MEL has been applied to the aircraft.

Data retrieved from NASA's ASRS site as of July 2013 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 line mechanic reports he mistakenly deactivated #2 engine anti-ice valve according to MEL 30-27-01A; instead of MEL 30-27-01A. Flight crew returned the A320 aircraft to gate after noticing improper anti-ice valve indication during engine start.