What was found
DURING A 12-YEAR INSPECTION, THE FUEL SHUTOFF VALVE WAS FOUND COCKED IN A WAY THAT PREVENTED THE VALVE FROM FULLY CLOSING DUE TO INTERFERENCE WITH THE MGB, AFT LET SUSPENSION BAR. IAW THE AMM, CHAPTER 28-21-00, 4-2 VALVE INSTALLATION, THERE IS A NOTE ABOUT THE CLEARANCE WITH THE SUSPENSION BAR. EVERY ACFT HAS THE FUEL SHUTOFF VALVE FT COMPLETED DURING A 600-FH/24-MONTH INSPECTION, REF MSM CHAPTER 05-22-00; AND AMM 28-21-00, 5-2, BUT AN INSPECTION OF THE CLEARANCE IS NOT SPECIFICALLY ADDRESSED DURING THIS CHECK, NOR DURING ANY OTHER CHECK AT THAT INSPECTION PERIOD. THIS CLEARANCE ISSUE IS AN AREA OF CONCERN FOR OTHER ACFT DUE TO THE FACT THAT THIS COULD PREVENT THE FUEL SUPPLY FROM BEING SHUTOFF TO THE ENGINE DURING AN EMERGENCY. TO HELP ELIMINATE THIS OCCURRENCE, AN IMMEDIATE INITIAL CHECK OF THE VALVE IS WARRANTED, AND RECURRING CHECKS AT THE 600-FH/24-MONTH INSPECTION INTERVAL SHOULD INCLUDE CHECKING THE VALVE FOR CLEARANCE WITH THE SUSPENSION BAR.