MODE C INOP IN CLASS B AIRSPACE. CTLR AWARE OF THIS ACFT PROB FROM PREVIOUS FLT.

Narrative

SHORTLY AFTER DEP FROM FORT WORTH MEACHAM ARPT; REGIONAL DEP ADVISED US THAT OUR MODE C WAS INOP. THE CTLR ASKED US TO RECYCLE THE XPONDER WHICH WE DID SEVERAL TIMES. EACH RECYCLE OF THE XPONDER DID NOT CAUSE THE MODE C TO OPERATE. THE CTLR ASKED WHERE THE ACFT WAS BASED AND GAVE US A PHONE NUMBER TO CALL. AFTER LNDG; I CALLED TRACON AND SPOKE TO MR X. HE TOLD ME THAT WHEN THE ACFT HAD FLOWN EARLIER THAT DAY; THE MODE C WAS INOP. HE HAD ASKED THE PF AT THAT TIME TO ADVISE THE SCHOOL THAT THE ACFT WAS NOT TO FLY AGAIN UNTIL THE MODE C WAS FIXED. THE PLT OF THAT FLT DID NOT SAY ANYTHING TO ME ABOUT THE MODE C PROB AND THERE WAS NO SQUAWK WRITTEN UP ON IT THAT I SAW. OUR MODE C DID COME ON LINE AFTER HDOF FROM MR X SECTOR AND PERFORMED FLAWLESSLY FOR THE REST OF THE FLT. UPON RETURN TO FTW; I TOLD THE CHIEF MECH AT FBO ABOUT THE PROB AND I GNDED THE ACFT. IN THE FUTURE; I SUGGEST THAT WHEN A CTLR HAS A PROB WITH AN ACFT'S MODE C THAT HE CALL THE SCHOOL BECAUSE WHEN AN ACFT IS RENTED; IT MAY FLY SEVERAL TIMES IN A DAY. THERE MAY ALSO BE SEVERAL PLTS WHO FLY THIS ACFT AND IF ONE FORGETS TO WRITE UP A PROB THE NEXT PLT WILL HAVE NO KNOWLEDGE IT EXISTS.