What was found
LEFT BLEED DUCT CAUTION MESSAGE APPEARED SHORTLY AFTER TAKEOFF. QRH PERFORMED & CONTACTED DISPATCHER & MX CONTROL WANTED US TO COME BACK. REST OF FLT FINISHED SAFELY. (FLIGHT 5010) ON ARRIVAL TO ACFT, INTERROGATED MDC FOUND BLEED DUCT FAULT MSG, CONDUCTED BLEED AIR LEAK DETECTION TEST & DETECTED A LT BLEED LOOP LEAK AT MT 141. PERFORMED VISUAL INSPECTION & LEAK CHKD OF LT BLEED LOOP & FOUND LT HOT AIR SHUT OFF VALVE INSULATION MUFF PARTIALLY OFF DUE TO AIR LEAKING & THE LOWER CLAMP LOOSE CAUSING A SIGNIFICANT BLEED AIR LOOP. R & R LT BLEED LOOP HOT AIR SHUT OFF VALVE IAW AMM 21-61-08. PERFORMED BLEED AIR LEAK CHECK OF LT BLEED LOOP HOT AIR SHUT OFF VALVE IAW AMM OF 21-53-00, NO LEAKS. ACFT GOOD RTS. ODI.