Narrative:

We started on our #2 engine boroscope at AM00. I opened up the work platform and unlatched the fan cowl, my partner pulled on the cowl as I drove it open for both left and right cowl (fan) doors. Then I got a bucket to catch oil from the drive pad. Removing the drive pad cover to turn by hand the N2 gear box. After boroscoping the turbine section, I inspected the drive pad cover mating surface, reinstalled the cover, then cleaned up the oil that the wind blew on the platform and reverser cowl. I proceeded to remove the buckets and rags from the platform, then got the cordless drill to drive the left cowling fully closed. Then I closed the right cowl to the full closed position. I laid the drill on the workstand, and then latched the 3 cowl latches closed. Moving back some of the safety platforms from the work stand, I closed the aircraft work platform and latched the safety pin, and went down the ladder. I stood on a portable work stand. I slid the ladder up into it's locked and stowed position, closing the lower access door, then going up to the workstand to help carry down the drill, light source, and boroscope box. Contributing factors: 1) I spent the first 4 hours of my day at the hospital with my son, when I normally sleep. 2) we were outside at AM00 in the morning, with the outside temperature about 48 degree F and the wind was about 10 mph. 3) no lights on workstand (moveable). 4) no inspection or sign-off paperwork for someone else to inspect the work. Because this engine is 50-60 ft off the ground, it's easily overlooked compared to a wing engine. The aircraft left den that morning. It was passing through 8000 to 10000 when they heard a loud boom. Then, a little later, they started losing oil quantity. On return to den, they found the right fan cowl open and twisted, cutting through the fuel oil heat exchanger and tearing holes in the reverser cowl. Corrective actions: 1) always inspect other people's work and have a sign-off on the paperwork. 2) better lighting at night on workstands. Human performance: working midnights, worrying about other things, getting enough sleep, not xchking or inspecting the other people's work. Supplemental information from acn 210872: my partner installed the drive pad cover ('O' ring type, no pad surface clean sign-off, gasket-type required) and closed the l-hand and r-hand fan cowls and the aircraft maintenance platform doors. He also stowed the ladder the ladder access door. I removed the #2 engine workstand. All work was performed per maintenance manual 72-01-00 and 72- 53-00. I received a phone call from mr X denver local am and was told there was an incident on aircraft. I arrived at the denver hangar at PM30. The aircraft was in the hangar and the work stand was positioned at the #2 engine. My observations at the #2 engine were, the l-hand forward fan cowl was open and it was fractured and bent across the length of the cowling, approximately 3/4 up from the bottom of the cowl. The l-hand reverser cowl had approximately 1 square ft of damage (gouged) on the lower forward corner and the fuel/oil heat exchanger was cut through its housing. Oil was leaking from the cut, cowling had oil in it and the reverser cowl was covered in oil. The core cowl was closed and latched. My partner said he closed the fan cowls and thought he had latched them. To prevent a similar incident, I suggest 1) the maintenance manual state to latch the cowling, not just close. 2) that the sign-off sheet also state to latch the cowling, not just close. 3)a write-up is initiated to close and latch each cowl. 4) a second person: mechanic, lead mechanic, or inspector, verifies the cowling is latched and closed. I hope I have explained this well enough and have provided useful information.

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Original NASA ASRS Text

Title: ACFT MAINT DISCREPANCY CAUSES INFLT ENG SHUTDOWN AND A RETURN LAND AFTER ACFT EQUIP PROBLEM IS EVIDENT.

Narrative: WE STARTED ON OUR #2 ENG BOROSCOPE AT AM00. I OPENED UP THE WORK PLATFORM AND UNLATCHED THE FAN COWL, MY PARTNER PULLED ON THE COWL AS I DROVE IT OPEN FOR BOTH L AND R COWL (FAN) DOORS. THEN I GOT A BUCKET TO CATCH OIL FROM THE DRIVE PAD. REMOVING THE DRIVE PAD COVER TO TURN BY HAND THE N2 GEAR BOX. AFTER BOROSCOPING THE TURBINE SECTION, I INSPECTED THE DRIVE PAD COVER MATING SURFACE, REINSTALLED THE COVER, THEN CLEANED UP THE OIL THAT THE WIND BLEW ON THE PLATFORM AND REVERSER COWL. I PROCEEDED TO REMOVE THE BUCKETS AND RAGS FROM THE PLATFORM, THEN GOT THE CORDLESS DRILL TO DRIVE THE L COWLING FULLY CLOSED. THEN I CLOSED THE R COWL TO THE FULL CLOSED POS. I LAID THE DRILL ON THE WORKSTAND, AND THEN LATCHED THE 3 COWL LATCHES CLOSED. MOVING BACK SOME OF THE SAFETY PLATFORMS FROM THE WORK STAND, I CLOSED THE ACFT WORK PLATFORM AND LATCHED THE SAFETY PIN, AND WENT DOWN THE LADDER. I STOOD ON A PORTABLE WORK STAND. I SLID THE LADDER UP INTO IT'S LOCKED AND STOWED POS, CLOSING THE LOWER ACCESS DOOR, THEN GOING UP TO THE WORKSTAND TO HELP CARRY DOWN THE DRILL, LIGHT SOURCE, AND BOROSCOPE BOX. CONTRIBUTING FACTORS: 1) I SPENT THE FIRST 4 HRS OF MY DAY AT THE HOSPITAL WITH MY SON, WHEN I NORMALLY SLEEP. 2) WE WERE OUTSIDE AT AM00 IN THE MORNING, WITH THE OUTSIDE TEMP ABOUT 48 DEG F AND THE WIND WAS ABOUT 10 MPH. 3) NO LIGHTS ON WORKSTAND (MOVEABLE). 4) NO INSPECTION OR SIGN-OFF PAPERWORK FOR SOMEONE ELSE TO INSPECT THE WORK. BECAUSE THIS ENG IS 50-60 FT OFF THE GND, IT'S EASILY OVERLOOKED COMPARED TO A WING ENG. THE ACFT LEFT DEN THAT MORNING. IT WAS PASSING THROUGH 8000 TO 10000 WHEN THEY HEARD A LOUD BOOM. THEN, A LITTLE LATER, THEY STARTED LOSING OIL QUANTITY. ON RETURN TO DEN, THEY FOUND THE R FAN COWL OPEN AND TWISTED, CUTTING THROUGH THE FUEL OIL HEAT EXCHANGER AND TEARING HOLES IN THE REVERSER COWL. CORRECTIVE ACTIONS: 1) ALWAYS INSPECT OTHER PEOPLE'S WORK AND HAVE A SIGN-OFF ON THE PAPERWORK. 2) BETTER LIGHTING AT NIGHT ON WORKSTANDS. HUMAN PERFORMANCE: WORKING MIDNIGHTS, WORRYING ABOUT OTHER THINGS, GETTING ENOUGH SLEEP, NOT XCHKING OR INSPECTING THE OTHER PEOPLE'S WORK. SUPPLEMENTAL INFO FROM ACN 210872: MY PARTNER INSTALLED THE DRIVE PAD COVER ('O' RING TYPE, NO PAD SURFACE CLEAN SIGN-OFF, GASKET-TYPE REQUIRED) AND CLOSED THE L-HAND AND R-HAND FAN COWLS AND THE ACFT MAINT PLATFORM DOORS. HE ALSO STOWED THE LADDER THE LADDER ACCESS DOOR. I REMOVED THE #2 ENG WORKSTAND. ALL WORK WAS PERFORMED PER MAINT MANUAL 72-01-00 AND 72- 53-00. I RECEIVED A PHONE CALL FROM MR X DENVER LCL AM AND WAS TOLD THERE WAS AN INCIDENT ON ACFT. I ARRIVED AT THE DENVER HANGAR AT PM30. THE ACFT WAS IN THE HANGAR AND THE WORK STAND WAS POSITIONED AT THE #2 ENG. MY OBSERVATIONS AT THE #2 ENG WERE, THE L-HAND FORWARD FAN COWL WAS OPEN AND IT WAS FRACTURED AND BENT ACROSS THE LENGTH OF THE COWLING, APPROX 3/4 UP FROM THE BOTTOM OF THE COWL. THE L-HAND REVERSER COWL HAD APPROX 1 SQUARE FT OF DAMAGE (GOUGED) ON THE LOWER FORWARD CORNER AND THE FUEL/OIL HEAT EXCHANGER WAS CUT THROUGH ITS HOUSING. OIL WAS LEAKING FROM THE CUT, COWLING HAD OIL IN IT AND THE REVERSER COWL WAS COVERED IN OIL. THE CORE COWL WAS CLOSED AND LATCHED. MY PARTNER SAID HE CLOSED THE FAN COWLS AND THOUGHT HE HAD LATCHED THEM. TO PREVENT A SIMILAR INCIDENT, I SUGGEST 1) THE MAINT MANUAL STATE TO LATCH THE COWLING, NOT JUST CLOSE. 2) THAT THE SIGN-OFF SHEET ALSO STATE TO LATCH THE COWLING, NOT JUST CLOSE. 3)A WRITE-UP IS INITIATED TO CLOSE AND LATCH EACH COWL. 4) A SECOND PERSON: MECH, LEAD MECH, OR INSPECTOR, VERIFIES THE COWLING IS LATCHED AND CLOSED. I HOPE I HAVE EXPLAINED THIS WELL ENOUGH AND HAVE PROVIDED USEFUL INFO.

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.