Narrative:

All events from pushback through application of takeoff power were uneventful. At approximately 100 KTS on takeoff roll we heard a pop and air surge from the air conditioning ducting behind the captain's seat. Both engines were checked and showed normal takeoff indications. Rotation and initial climb out were also normal. During flap retraction from 5 degrees to 1 degree, the aircraft began to vibrate slightly. When flaps were retracted up, the aircraft vibrated more noticeably and we immediately got a leading edge asymmetry light on EICAS and the leading edge light on the forward panel. A flight attendant called from the mid and said that a passenger showed her that the 'left engine cowl came loose and was bent up over the wing.' an emergency was declared, the checklist was accomplished, and a return to lax was made. A trailing edge flaps 20 degree landing on runway 25L was made. Gross weight was 310000 pounds, touchdown was in the landing zone and gentle, airspeed was 165-170 KTS, autobrakes 4. The right reverser worked normally but the left reverser unlocked only. We exited the runway at 1500-2000 ft remaining and terminated the emergency but requested that 1 fire truck stay with us in the event that the brakes might overheat. Aircraft was towed in to the gate and passenger deplaned normally. Postflt inspection showed the outboard inspection/service panel on the aft section of the left engine had sheared its latches and bent up and onto the slat just behind the engine. WX in lax was 10 SM visibility broken 1500 ft overcast 2000 ft, 21/17, altimeter 29.87. Supplemental information from acn 558493: during takeoff roll at 100 KIAS, both pilots heard a muffled 'roar,' surge-like sound. No cockpit indications. After retracting the flaps from 5 degrees towards 1 degree, got a leading edge asymmetry light on forward discrete panel and EICAS screen. Cabin observers reported that there was a piece of metal outboard #1 engine resting on leading edge. Declared emergency and landed. Post inspection revealed aft 2 eyebolts sheared on the cowling aft of the bypass on the #1 engine.

Google
 

Original NASA ASRS Text

Title: B767-300ER CREW HAD AN EICAS 'LEADING EDGE ASYMMETRY' AND EXPANDED LEADING EDGE FLAP DISPLAY IN SCT CLASS B AIRSPACE.

Narrative: ALL EVENTS FROM PUSHBACK THROUGH APPLICATION OF TKOF PWR WERE UNEVENTFUL. AT APPROX 100 KTS ON TKOF ROLL WE HEARD A POP AND AIR SURGE FROM THE AIR CONDITIONING DUCTING BEHIND THE CAPT'S SEAT. BOTH ENGS WERE CHKED AND SHOWED NORMAL TKOF INDICATIONS. ROTATION AND INITIAL CLBOUT WERE ALSO NORMAL. DURING FLAP RETRACTION FROM 5 DEGS TO 1 DEG, THE ACFT BEGAN TO VIBRATE SLIGHTLY. WHEN FLAPS WERE RETRACTED UP, THE ACFT VIBRATED MORE NOTICEABLY AND WE IMMEDIATELY GOT A LEADING EDGE ASYMMETRY LIGHT ON EICAS AND THE LEADING EDGE LIGHT ON THE FORWARD PANEL. A FLT ATTENDANT CALLED FROM THE MID AND SAID THAT A PAX SHOWED HER THAT THE 'L ENG COWL CAME LOOSE AND WAS BENT UP OVER THE WING.' AN EMER WAS DECLARED, THE CHKLIST WAS ACCOMPLISHED, AND A RETURN TO LAX WAS MADE. A TRAILING EDGE FLAPS 20 DEG LNDG ON RWY 25L WAS MADE. GROSS WT WAS 310000 LBS, TOUCHDOWN WAS IN THE LNDG ZONE AND GENTLE, AIRSPD WAS 165-170 KTS, AUTOBRAKES 4. THE R REVERSER WORKED NORMALLY BUT THE L REVERSER UNLOCKED ONLY. WE EXITED THE RWY AT 1500-2000 FT REMAINING AND TERMINATED THE EMER BUT REQUESTED THAT 1 FIRE TRUCK STAY WITH US IN THE EVENT THAT THE BRAKES MIGHT OVERHEAT. ACFT WAS TOWED IN TO THE GATE AND PAX DEPLANED NORMALLY. POSTFLT INSPECTION SHOWED THE OUTBOARD INSPECTION/SVC PANEL ON THE AFT SECTION OF THE L ENG HAD SHEARED ITS LATCHES AND BENT UP AND ONTO THE SLAT JUST BEHIND THE ENG. WX IN LAX WAS 10 SM VISIBILITY BROKEN 1500 FT OVCST 2000 FT, 21/17, ALTIMETER 29.87. SUPPLEMENTAL INFO FROM ACN 558493: DURING TKOF ROLL AT 100 KIAS, BOTH PLTS HEARD A MUFFLED 'ROAR,' SURGE-LIKE SOUND. NO COCKPIT INDICATIONS. AFTER RETRACTING THE FLAPS FROM 5 DEGS TOWARDS 1 DEG, GOT A LEADING EDGE ASYMMETRY LIGHT ON FORWARD DISCRETE PANEL AND EICAS SCREEN. CABIN OBSERVERS RPTED THAT THERE WAS A PIECE OF METAL OUTBOARD #1 ENG RESTING ON LEADING EDGE. DECLARED EMER AND LANDED. POST INSPECTION REVEALED AFT 2 EYEBOLTS SHEARED ON THE COWLING AFT OF THE BYPASS ON THE #1 ENG.

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.