What was found
#1 MAIN FUEL TK READ IMBAL AT LEVEL OFF @ FL 210. ATTEMPTED FUEL BALANCE BUT # 1 TANK CONTINUED TO DECREASE . FUEL LEAK CKLIST RAN ; SHUT DOWN #1 AND RETURNED TO DAL SINGLE ENG.<[01] PERFORMED #1 WET CAPACITANCE CHECK PER AMM 28-41-21. VALUES ARE WITHIN LIMITS.;[02] ADDED TOOL INFORMATION;[03] ADDED TOOLING;[04] PERFORMED FQIS BITE CHECK PER FIM 28-41 TASK 801. NO FAULTS; GROUND TEST PASSED. CROSSFEED VALVE FUNCTIONAL TEST IAW 28-22-00 OPS CHECKS GOOD.;[05] TANK TO TANK FUEL TRANSFER OPS CHECKS OK PER AMM 28-26-00. NO FUEL LEAKS NOTED AROUND #1 TANK UPON WALK AROUND INSPECTION.;[06] RAN ENGINES I.A.W 71-00-00 NO LEAKS NOTED. PERFORMED CONDITIONAL INSPECTION 05-51-48. NO DEFECTS NOTED. A/C OK FOR SERVICE.