Narrative:

The purpose of the flight was to support our 2 jet aircraft. The first leg was VFR to ZZZ to drop off parts at FBO X for our lockheed jetstar. Leg #2 was over to ZZZ1 to pick up brakes, tires and wheels for our lear 24. I am first officer on both these aircraft and am well trained. Leaving ZZZ1 at approximately XA00, I checked in with departure and was told to squawk XXXX. Radar contact was made, but the controller said I was squawking xxyx. My transponder indicated XXXX. I moved the first number and the controller said it was good. The remainder of the flight was fine. Leg #2: after takeoff, I complied with my clearance and in the right turn, ZZZ2 tower told me to contact ZZZ3 tower. The ZZZ3 controller told me to cross midfield. North of ZZZ3, the controller said to squawk VFR. I looked at my transponder and it was indicating 1200. I moved all of the numbers to the right, then back to the left while contacting departure before entering the class C airspace at ZZZ1. Departure was unable to receive my transponder at all. I was told to contact ZZZ1 tower. The tower at ZZZ1 also was unable to pick up my transponder. My concern is that the transponder may have been indicating something other than 1200. ZZZ2 tower did not say anything, but ZZZ3 tower said to squawk VFR. Leg #3: departing ZZZ1 to ZZZ4, clearance told me they were unable to provide class C service without a transponder. I then requested a right downwind departure, under the class C, then climbed to 5500 ft MSL VFR to ZZZ4. Maintenance checked the transponder, and I flew the airplane on apr/mon/01 checking in with departure over ZZZ4. Departure could only receive the primary. We have the airplane at FBO Y installing a new transponder.

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Original NASA ASRS Text

Title: A PA32 HAS RECURRING XPONDER MODE C PROBS THAT ARE FINALLY RESOLVED BY A UNIT CHANGE.

Narrative: THE PURPOSE OF THE FLT WAS TO SUPPORT OUR 2 JET ACFT. THE FIRST LEG WAS VFR TO ZZZ TO DROP OFF PARTS AT FBO X FOR OUR LOCKHEED JETSTAR. LEG #2 WAS OVER TO ZZZ1 TO PICK UP BRAKES, TIRES AND WHEELS FOR OUR LEAR 24. I AM FO ON BOTH THESE ACFT AND AM WELL TRAINED. LEAVING ZZZ1 AT APPROX XA00, I CHKED IN WITH DEP AND WAS TOLD TO SQUAWK XXXX. RADAR CONTACT WAS MADE, BUT THE CTLR SAID I WAS SQUAWKING XXYX. MY XPONDER INDICATED XXXX. I MOVED THE FIRST NUMBER AND THE CTLR SAID IT WAS GOOD. THE REMAINDER OF THE FLT WAS FINE. LEG #2: AFTER TKOF, I COMPLIED WITH MY CLRNC AND IN THE R TURN, ZZZ2 TWR TOLD ME TO CONTACT ZZZ3 TWR. THE ZZZ3 CTLR TOLD ME TO CROSS MIDFIELD. N OF ZZZ3, THE CTLR SAID TO SQUAWK VFR. I LOOKED AT MY XPONDER AND IT WAS INDICATING 1200. I MOVED ALL OF THE NUMBERS TO THE R, THEN BACK TO THE L WHILE CONTACTING DEP BEFORE ENTERING THE CLASS C AIRSPACE AT ZZZ1. DEP WAS UNABLE TO RECEIVE MY XPONDER AT ALL. I WAS TOLD TO CONTACT ZZZ1 TWR. THE TWR AT ZZZ1 ALSO WAS UNABLE TO PICK UP MY XPONDER. MY CONCERN IS THAT THE XPONDER MAY HAVE BEEN INDICATING SOMETHING OTHER THAN 1200. ZZZ2 TWR DID NOT SAY ANYTHING, BUT ZZZ3 TWR SAID TO SQUAWK VFR. LEG #3: DEPARTING ZZZ1 TO ZZZ4, CLRNC TOLD ME THEY WERE UNABLE TO PROVIDE CLASS C SVC WITHOUT A XPONDER. I THEN REQUESTED A R DOWNWIND DEP, UNDER THE CLASS C, THEN CLBED TO 5500 FT MSL VFR TO ZZZ4. MAINT CHKED THE XPONDER, AND I FLEW THE AIRPLANE ON APR/MON/01 CHKING IN WITH DEP OVER ZZZ4. DEP COULD ONLY RECEIVE THE PRIMARY. WE HAVE THE AIRPLANE AT FBO Y INSTALLING A NEW XPONDER.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.