Narrative:

Through 10000 ft flight attendant reported a passenger notified her of an open panel on engine cowling. I visually confirmed this to be true. No damage. Maintained low airspeed and landed at palm springs (approved alternate airport) and had ground personnel close and secure panel and verify no damage. I then visually confirmed panel closed and secure. Refueled and resumed flight to dfw. Supplemental information from acn 262834: on exterior preflight inspection, panel was definitely not open, but it is possible that the latch was not secure.

Google
 

Original NASA ASRS Text

Title: ACFT MAINT DEFICIENCY NOTED BY PAX IN CLB.

Narrative: THROUGH 10000 FT FLT ATTENDANT RPTED A PAX NOTIFIED HER OF AN OPEN PANEL ON ENG COWLING. I VISUALLY CONFIRMED THIS TO BE TRUE. NO DAMAGE. MAINTAINED LOW AIRSPD AND LANDED AT PALM SPRINGS (APPROVED ALTERNATE ARPT) AND HAD GND PERSONNEL CLOSE AND SECURE PANEL AND VERIFY NO DAMAGE. I THEN VISUALLY CONFIRMED PANEL CLOSED AND SECURE. REFUELED AND RESUMED FLT TO DFW. SUPPLEMENTAL INFO FROM ACN 262834: ON EXTERIOR PREFLT INSPECTION, PANEL WAS DEFINITELY NOT OPEN, BUT IT IS POSSIBLE THAT THE LATCH WAS NOT SECURE.

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.