Wrong circuit breaker pulled on B-757 by all 3 mechanics who worked the aircraft.

Attributes
ACN	271279
Time
Date	199405
Day	Sun
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : ord
State Reference	IL
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	B757 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	ground : preflight
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	other personnel other
Qualification	other other : other
ASRS Report	271279
Person 2
Affiliation	company : air carrier
Function	other personnel other
Qualification	other other : other
ASRS Report	271027
Events
Anomaly	aircraft equipment problem : critical non adherence : published procedure
Independent Detector	other other : unspecified
Resolutory Action	none taken : detected after the fact
Consequence	Other
Supplementary
Primary Problem	Chart Or Publication
Air Traffic Incident	other
Situations
Publication	Unspecified

Narrative:

On may/xx/94, airlines aircraft required the left engine thrust reverser be deactivated per the 757 MEL account of hydraulic fluid leakage on 1 actuator. Step 11 of MEL reference 7831C required the pulling and safetying of the appropriate circuit breaker. Subsequently, it was discovered that the wrong breaker had been pulled. MEL 7831C specifies 6j17 be pulled, and I pulled a thrust reverser primary control breaker, located, to be later ascertained, the 6TH breaker in row K of a different circuit breaker panel. This was discovered during a return to the gate on the following day (may/yy/94). I pulled the breaker which later proved to be the wrong breaker to pull. I believe the MEL specification is somewhat vague, particularly the panel and circuit breaker location and identify. I wish to point out that a crew of 3 men were involved in the deferral procedure, and that I was responsible for the pulling and safetying of the above mentioned circuit breaker. Finally, I wish to point out that this occurred during a routine #1 service check (through trip) with minimal ground time available, and several individuals in the cockpit throughout the procedure. Although not offered as an excuse, I view these as contributing factors leading up to this situation as described.

Original NASA ASRS Text

Title: WRONG CIRCUIT BREAKER PULLED ON B-757 BY ALL 3 MECHS WHO WORKED THE ACFT.

Narrative: ON MAY/XX/94, AIRLINES ACFT REQUIRED THE L ENG THRUST REVERSER BE DEACTIVATED PER THE 757 MEL ACCOUNT OF HYD FLUID LEAKAGE ON 1 ACTUATOR. STEP 11 OF MEL REF 7831C REQUIRED THE PULLING AND SAFETYING OF THE APPROPRIATE CIRCUIT BREAKER. SUBSEQUENTLY, IT WAS DISCOVERED THAT THE WRONG BREAKER HAD BEEN PULLED. MEL 7831C SPECIFIES 6J17 BE PULLED, AND I PULLED A THRUST REVERSER PRIMARY CTL BREAKER, LOCATED, TO BE LATER ASCERTAINED, THE 6TH BREAKER IN ROW K OF A DIFFERENT CIRCUIT BREAKER PANEL. THIS WAS DISCOVERED DURING A RETURN TO THE GATE ON THE FOLLOWING DAY (MAY/YY/94). I PULLED THE BREAKER WHICH LATER PROVED TO BE THE WRONG BREAKER TO PULL. I BELIEVE THE MEL SPEC IS SOMEWHAT VAGUE, PARTICULARLY THE PANEL AND CIRCUIT BREAKER LOCATION AND IDENT. I WISH TO POINT OUT THAT A CREW OF 3 MEN WERE INVOLVED IN THE DEFERRAL PROC, AND THAT I WAS RESPONSIBLE FOR THE PULLING AND SAFETYING OF THE ABOVE MENTIONED CIRCUIT BREAKER. FINALLY, I WISH TO POINT OUT THAT THIS OCCURRED DURING A ROUTINE #1 SVC CHK (THROUGH TRIP) WITH MINIMAL GND TIME AVAILABLE, AND SEVERAL INDIVIDUALS IN THE COCKPIT THROUGHOUT THE PROC. ALTHOUGH NOT OFFERED AS AN EXCUSE, I VIEW THESE AS CONTRIBUTING FACTORS LEADING UP TO THIS SIT AS DESCRIBED.

Data retrieved from NASA's ASRS site as of July 2007 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.