Narrative:

I received the gate call 10 mins after scheduled push time. The initial report was; both lavatories inoperative; would not flush. Myself and another mechanic arrived at the aircraft. I checked the tank dump handle to be sure it was fully seated while person #2 went upstairs to check the lavatory. The handle was seated correctly so person #2 checked the circuit breaker in the east&east compartment and found it popped. The circuit breaker was reset and we operated the forward lavatory flush switch; no suction was observed. I assumed the circuit breaker popped again. At this time it was decided to MEL the lavatory blower system. Due to operational needs; person #2 returned to the office for further assignments. I proceeded with the deferral procedure and was instructed by maintenance control to comply with MEL special procedures collaring of the popped circuit breaker. I entered the east&east bay and located the circuit breaker on the P-91 panel for the lavatory blower control. I did not doublechk with person #2 as to exactly which circuit breaker he reset. I assumed the circuit breaker on the front of the P-91 was the circuit breaker in question. I thought the circuit breaker had not fully popped so I pulled and collared the vacuum control circuit breaker. I was unaware of the additional circuit breaker inside the P-91 panel. Upon returning to the office after my next call; I checked the system schematic and was concerned I had deactivated the system completely. At this time I notified my manager of the suspected error. In a short time we were notified of the diversion to ZZZ. One contributing factor was my failure to review all MEL procedures due to the difficulty obtaining the information on the fly. Although the MEL is available in the operations center and at the gate reader; it is often not accessible due to those system being in use. Also our office computers are several mins from this particular gate with personnel busy with other calls so further delay would have been incurred. Further; I feel additional verbiage in the MEL regarding the location of the circuit breaker inside the P-91 panel would be helpful along with distinct markings on the P-91 panel warning of the deactivation of the vacuum control circuit breaker. Supplemental information from acn 792531: it slipped my mind to inform person #1 that the tripped circuit breaker was inside the P-91 panel; not on the outside. If I would have communicated better with person #1; this event would not have happened. He ended up collaring the wrong circuit breaker; which caused the aircraft to divert to ZZZ; for both lavatories inoperative in the air. He collared the vacuum waste control circuit breaker on the outside of the P-91 panel by mistake.

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Original NASA ASRS Text

Title: TWO MECHANICS WORKING A B737-700; EXPLAIN HOW A CIRCUIT BREAKER ON THE OUTSIDE OF THE P-91 PANEL WAS MISTAKENLY PULLED AND COLLARED; SHUTTING DOWN THE VACUUM WASTE CONTROL FOR BOTH CABIN LAVS; REQUIRING ACFT TO DIVERT.

Narrative: I RECEIVED THE GATE CALL 10 MINS AFTER SCHEDULED PUSH TIME. THE INITIAL RPT WAS; BOTH LAVATORIES INOP; WOULD NOT FLUSH. MYSELF AND ANOTHER MECH ARRIVED AT THE ACFT. I CHKED THE TANK DUMP HANDLE TO BE SURE IT WAS FULLY SEATED WHILE PERSON #2 WENT UPSTAIRS TO CHK THE LAVATORY. THE HANDLE WAS SEATED CORRECTLY SO PERSON #2 CHKED THE CIRCUIT BREAKER IN THE E&E COMPARTMENT AND FOUND IT POPPED. THE CIRCUIT BREAKER WAS RESET AND WE OPERATED THE FORWARD LAVATORY FLUSH SWITCH; NO SUCTION WAS OBSERVED. I ASSUMED THE CIRCUIT BREAKER POPPED AGAIN. AT THIS TIME IT WAS DECIDED TO MEL THE LAVATORY BLOWER SYS. DUE TO OPERATIONAL NEEDS; PERSON #2 RETURNED TO THE OFFICE FOR FURTHER ASSIGNMENTS. I PROCEEDED WITH THE DEFERRAL PROC AND WAS INSTRUCTED BY MAINT CTL TO COMPLY WITH MEL SPECIAL PROCS COLLARING OF THE POPPED CIRCUIT BREAKER. I ENTERED THE E&E BAY AND LOCATED THE CIRCUIT BREAKER ON THE P-91 PANEL FOR THE LAVATORY BLOWER CTL. I DID NOT DOUBLECHK WITH PERSON #2 AS TO EXACTLY WHICH CIRCUIT BREAKER HE RESET. I ASSUMED THE CIRCUIT BREAKER ON THE FRONT OF THE P-91 WAS THE CIRCUIT BREAKER IN QUESTION. I THOUGHT THE CIRCUIT BREAKER HAD NOT FULLY POPPED SO I PULLED AND COLLARED THE VACUUM CTL CIRCUIT BREAKER. I WAS UNAWARE OF THE ADDITIONAL CIRCUIT BREAKER INSIDE THE P-91 PANEL. UPON RETURNING TO THE OFFICE AFTER MY NEXT CALL; I CHKED THE SYS SCHEMATIC AND WAS CONCERNED I HAD DEACTIVATED THE SYS COMPLETELY. AT THIS TIME I NOTIFIED MY MGR OF THE SUSPECTED ERROR. IN A SHORT TIME WE WERE NOTIFIED OF THE DIVERSION TO ZZZ. ONE CONTRIBUTING FACTOR WAS MY FAILURE TO REVIEW ALL MEL PROCS DUE TO THE DIFFICULTY OBTAINING THE INFO ON THE FLY. ALTHOUGH THE MEL IS AVAILABLE IN THE OPS CTR AND AT THE GATE READER; IT IS OFTEN NOT ACCESSIBLE DUE TO THOSE SYS BEING IN USE. ALSO OUR OFFICE COMPUTERS ARE SEVERAL MINS FROM THIS PARTICULAR GATE WITH PERSONNEL BUSY WITH OTHER CALLS SO FURTHER DELAY WOULD HAVE BEEN INCURRED. FURTHER; I FEEL ADDITIONAL VERBIAGE IN THE MEL REGARDING THE LOCATION OF THE CIRCUIT BREAKER INSIDE THE P-91 PANEL WOULD BE HELPFUL ALONG WITH DISTINCT MARKINGS ON THE P-91 PANEL WARNING OF THE DEACTIVATION OF THE VACUUM CTL CIRCUIT BREAKER. SUPPLEMENTAL INFO FROM ACN 792531: IT SLIPPED MY MIND TO INFORM PERSON #1 THAT THE TRIPPED CIRCUIT BREAKER WAS INSIDE THE P-91 PANEL; NOT ON THE OUTSIDE. IF I WOULD HAVE COMMUNICATED BETTER WITH PERSON #1; THIS EVENT WOULD NOT HAVE HAPPENED. HE ENDED UP COLLARING THE WRONG CIRCUIT BREAKER; WHICH CAUSED THE ACFT TO DIVERT TO ZZZ; FOR BOTH LAVATORIES INOP IN THE AIR. HE COLLARED THE VACUUM WASTE CTL CIRCUIT BREAKER ON THE OUTSIDE OF THE P-91 PANEL BY MISTAKE.

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.