Narrative:

Scheduled workload for aircraft X was a service check #1 engine fan frame inspection; altimeter manual replacement; defibrillator battery replacement. Upon arrival to aircraft; I svced engine oil; checked tire condition and pressure and wiped struts. I checked logbook and turned on exterior lights and walked around aircraft checking lights and clearing flap areas for deployment. I turned off lights and lowered flaps for exterior walkaround; also raised spoilers. I walked through cabin; svced lavatory waste lines and performed other interior and control cabin inspections. Once finished; I began exterior walkaround inspection beginning on captain's side at radome; and proceeded to engine and opened inboard and outboard fan cowls. Shortly after my lead arrived to check on the aircraft and see if I needed anything; I asked him to call quality control to let them know I was ready for the #1 engine fan frame inspection. Lead called and informed the inspector. Continuing the walkaround inspection; I realized I needed to open #1 engine outboard core cowl for the fan frame inspection. Just then inspector arrived and I told him I needed to open the core cowl and I needed to get a core cowl pump. Inspector said no problem; and I left to get the pump. When I returned I proceeded opening the core cowl; during which I noticed oil leaking from the connection at the opening actuator. I tightened a loose 'B' nut and continued opening the core cowl; not realizing the core cowl was contacting the #4 slat. I punctured the aft outer skin of the core cowl. I believe what contributed to the event causing the damage was I became out of sync not completing the walkaround inspection before performing the fan frame inspection. Had I completed the walkaround; I would have finished by raising the flaps and slats; thus providing clearance to fully open the outboard core cowl.

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Original NASA ASRS Text

Title: B737-700 #1 ENG CORE COWLING WAS DAMAGED WHEN THE TECHNICIAN OPENING THE COWLING WITH A HYD PUMP CONTACTED THE LEADING EDGE DEVICE PREVIOUSLY DEPLOYED BY THE TECHNICIAN.

Narrative: SCHEDULED WORKLOAD FOR ACFT X WAS A SVC CHK #1 ENG FAN FRAME INSPECTION; ALTIMETER MANUAL REPLACEMENT; DEFIBRILLATOR BATTERY REPLACEMENT. UPON ARR TO ACFT; I SVCED ENG OIL; CHKED TIRE CONDITION AND PRESSURE AND WIPED STRUTS. I CHKED LOGBOOK AND TURNED ON EXTERIOR LIGHTS AND WALKED AROUND ACFT CHKING LIGHTS AND CLRING FLAP AREAS FOR DEPLOYMENT. I TURNED OFF LIGHTS AND LOWERED FLAPS FOR EXTERIOR WALKAROUND; ALSO RAISED SPOILERS. I WALKED THROUGH CABIN; SVCED LAVATORY WASTE LINES AND PERFORMED OTHER INTERIOR AND CTL CABIN INSPECTIONS. ONCE FINISHED; I BEGAN EXTERIOR WALKAROUND INSPECTION BEGINNING ON CAPT'S SIDE AT RADOME; AND PROCEEDED TO ENG AND OPENED INBOARD AND OUTBOARD FAN COWLS. SHORTLY AFTER MY LEAD ARRIVED TO CHK ON THE ACFT AND SEE IF I NEEDED ANYTHING; I ASKED HIM TO CALL QUALITY CTL TO LET THEM KNOW I WAS READY FOR THE #1 ENG FAN FRAME INSPECTION. LEAD CALLED AND INFORMED THE INSPECTOR. CONTINUING THE WALKAROUND INSPECTION; I REALIZED I NEEDED TO OPEN #1 ENG OUTBOARD CORE COWL FOR THE FAN FRAME INSPECTION. JUST THEN INSPECTOR ARRIVED AND I TOLD HIM I NEEDED TO OPEN THE CORE COWL AND I NEEDED TO GET A CORE COWL PUMP. INSPECTOR SAID NO PROB; AND I LEFT TO GET THE PUMP. WHEN I RETURNED I PROCEEDED OPENING THE CORE COWL; DURING WHICH I NOTICED OIL LEAKING FROM THE CONNECTION AT THE OPENING ACTUATOR. I TIGHTENED A LOOSE 'B' NUT AND CONTINUED OPENING THE CORE COWL; NOT REALIZING THE CORE COWL WAS CONTACTING THE #4 SLAT. I PUNCTURED THE AFT OUTER SKIN OF THE CORE COWL. I BELIEVE WHAT CONTRIBUTED TO THE EVENT CAUSING THE DAMAGE WAS I BECAME OUT OF SYNC NOT COMPLETING THE WALKAROUND INSPECTION BEFORE PERFORMING THE FAN FRAME INSPECTION. HAD I COMPLETED THE WALKAROUND; I WOULD HAVE FINISHED BY RAISING THE FLAPS AND SLATS; THUS PROVIDING CLRNC TO FULLY OPEN THE OUTBOARD CORE COWL.

Data retrieved from NASA's ASRS site as of January 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.