What was found
AIRCRAFT GROUNDED DUE TO THE FOLLOWING ISSUE - REFERENCE LP259071, ITEM 1. PANEL MISSING FROM TOP OF RIGHT WING DIRECTLY ABOVE ENGINE PYLON (621BT) ARRIVED IN SEA AT 0918, UPON TAXI INTO THE GATE, A PASSENGER POINTED OUT THAT PANEL 621BT LEADING EDGE ACCESS PANEL WAS MISSING. INVESTIGATION FOUND PANEL WAS PREVIOUSLY REMOVED AND INSTALLED TO FACILITATE OTHER MAINTENANCE IN LAS THE NIGHT PRIOR FOR A CLASS II AIRBLEED MEL. SEE LP259065, ITEM 2. A/C IS CURRENTLY AOG UNTIL FULL INVESTIGATION AND REPLACEMENT OF PANEL IS COMPLETED. CORRECTIVE ACTION: REF; MFFR#1207354 PANEL 621BT. PANEL FROM TOP DIRECTLY ABOVE ENGINE PYLON WAS INSTALLED I.A.W. AMM 57-41-37-400-009-A