Narrative:

Jul/mon/99, XA30, started installation of #1 engine FCU and pump assembly on aircraft xyz. We did leak check and engine run-up. I made adjustments to FCU idle. Closed inboard cowl securing only 2 forward latches. Taxied to run-up area and made 2 or 3 more adjustments to maximum power settings. Again securing only the 2 forward latches on the inboard cowling. Taxied back to ramp area and do not recall closing the rest of the latches '3 each' on the inboard cowling of #1 engine. I was released from work after we made sure all paperwork was completed with maintenance control at about XH15 am. Aircraft was still being worked on for other maintenance. Aircraft later departed and at approximately FL240 the cowling came open and lower outboard cowl departed aircraft. The aircraft returned safely. Callback conversation with reporter revealed the following information: the reporter stated the fuel control was replaced and 2 runs were made for maximum power and idle adjustment with only 2 of 5 cowling latches locked. The reporter said he does not recall after the aircraft returned from the run check if all the latches were secured.

Google
 

Original NASA ASRS Text

Title: A FALCON DA20 IN CLB AT FL240 DECLARED AN EMER AND DIVERTED DUE TO LOSS OF #1 ENG LOWER OUTBOARD COWLING CAUSED BY FAILURE TO SECURE LATCHES AFTER MAINT.

Narrative: JUL/MON/99, XA30, STARTED INSTALLATION OF #1 ENG FCU AND PUMP ASSEMBLY ON ACFT XYZ. WE DID LEAK CHK AND ENG RUN-UP. I MADE ADJUSTMENTS TO FCU IDLE. CLOSED INBOARD COWL SECURING ONLY 2 FORWARD LATCHES. TAXIED TO RUN-UP AREA AND MADE 2 OR 3 MORE ADJUSTMENTS TO MAX PWR SETTINGS. AGAIN SECURING ONLY THE 2 FORWARD LATCHES ON THE INBOARD COWLING. TAXIED BACK TO RAMP AREA AND DO NOT RECALL CLOSING THE REST OF THE LATCHES '3 EACH' ON THE INBOARD COWLING OF #1 ENG. I WAS RELEASED FROM WORK AFTER WE MADE SURE ALL PAPERWORK WAS COMPLETED WITH MAINT CTL AT ABOUT XH15 AM. ACFT WAS STILL BEING WORKED ON FOR OTHER MAINT. ACFT LATER DEPARTED AND AT APPROX FL240 THE COWLING CAME OPEN AND LOWER OUTBOARD COWL DEPARTED ACFT. THE ACFT RETURNED SAFELY. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE FUEL CTL WAS REPLACED AND 2 RUNS WERE MADE FOR MAX PWR AND IDLE ADJUSTMENT WITH ONLY 2 OF 5 COWLING LATCHES LOCKED. THE RPTR SAID HE DOES NOT RECALL AFTER THE ACFT RETURNED FROM THE RUN CHK IF ALL THE LATCHES WERE SECURED.

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.