GA pilot experiences intermittent transponder.

Attributes
ACN	174344
Time
Date	199103
Day	Thu
Place
Locale Reference	airport : pwk
State Reference	IL
Altitude	msl bound lower : 1750 msl bound upper : 1750
Environment
Flight Conditions	VMC
Aircraft 1
Controlling Facilities	tower : pwk
Operator	general aviation : personal
Make Model Name	Small Aircraft, High Wing, 1 Eng, Fixed Gear
Flight Phase	cruise other other
Flight Plan	VFR
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : cfi pilot : commercial pilot : instrument
Experience	flight time last 90 days : 350 flight time total : 950 flight time type : 650
ASRS Report	174344
Person 2
Affiliation	government : faa
Function	controller : local
Qualification	controller : non radar
Events
Anomaly	aircraft equipment problem : less severe non adherence : far
Independent Detector	other controllera
Resolutory Action	other
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

During the past week or 2, we have either been told to recycle our transponder or no mode C. After recycling the transponder, the tower would either pick up us on radar or report again no mode C. We have had problems in the past with communications with pwk tower, as others have also. As pilot, I had the green light blinking in the corner indicating that we were sending out a signal. When the transponder is in the test mode, it shows a bright green light indicating operation is ok. These are the only tests a pilot can do to test the transponder before flying. After no mode C was reported 2 days in a row, I had the mechanic check the transponder. He found a loose wire that seemed to fix the problem. My very next flight mode C was again reported inoperative. After troubleshooting the problem, I found the wrong fuse in place for the radio and transponder. This seemed to fix the problem. During this period, I called the GADO office to get information on operating an aircraft with a problem that only occurs after the flight has begun and does not always happen. Their advice was to get it checked out, because if they hear about an intermittent problem with mode C, they will investigate the problem.

Original NASA ASRS Text

Title: GA PLT EXPERIENCES INTERMITTENT TRANSPONDER.

Narrative: DURING THE PAST WEEK OR 2, WE HAVE EITHER BEEN TOLD TO RECYCLE OUR XPONDER OR NO MODE C. AFTER RECYCLING THE XPONDER, THE TWR WOULD EITHER PICK UP US ON RADAR OR RPT AGAIN NO MODE C. WE HAVE HAD PROBS IN THE PAST WITH COMS WITH PWK TWR, AS OTHERS HAVE ALSO. AS PLT, I HAD THE GREEN LIGHT BLINKING IN THE CORNER INDICATING THAT WE WERE SENDING OUT A SIGNAL. WHEN THE XPONDER IS IN THE TEST MODE, IT SHOWS A BRIGHT GREEN LIGHT INDICATING OPERATION IS OK. THESE ARE THE ONLY TESTS A PLT CAN DO TO TEST THE XPONDER BEFORE FLYING. AFTER NO MODE C WAS RPTED 2 DAYS IN A ROW, I HAD THE MECH CHK THE XPONDER. HE FOUND A LOOSE WIRE THAT SEEMED TO FIX THE PROB. MY VERY NEXT FLT MODE C WAS AGAIN RPTED INOP. AFTER TROUBLESHOOTING THE PROB, I FOUND THE WRONG FUSE IN PLACE FOR THE RADIO AND XPONDER. THIS SEEMED TO FIX THE PROB. DURING THIS PERIOD, I CALLED THE GADO OFFICE TO GET INFO ON OPERATING AN ACFT WITH A PROB THAT ONLY OCCURS AFTER THE FLT HAS BEGUN AND DOES NOT ALWAYS HAPPEN. THEIR ADVICE WAS TO GET IT CHKED OUT, BECAUSE IF THEY HEAR ABOUT AN INTERMITTENT PROB WITH MODE C, THEY WILL INVESTIGATE THE PROB.

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.