Narrative:

We were working flight en route from ZZZ1 to ZZZ3. At level off the master caution and the air conditioning lights illuminated. Looking at the air conditioning panel the right wing body overheat light was illuminated. I called for and the captain completed the wing body overheat checklist from the QRH. The light did not extinguish even after isolating the right side. It remained illuminated and kept resetting the master caution light. At that point we declared an emergency with center and requested and landing at ZZZ. Due to our altitude and localizer, ZZZ2 and all the airports in the area were equal time away. We decided on ZZZ due to the maintenance facilities, area medical facilities, and ZZZ runway. We landed without incident, stopped the aircraft on the runway, and shut down the number two engine. Emergency vehicles met the aircraft and advised us that they could not see any damage. We then taxied to the gate in ZZZ. Maintenance met the aircraft and discovered two different problems. The first was a small bleed air leak located where the external air is connected to the aircraft, and also in addition they discovered a fault in the detection system. Callback conversation with reporter revealed the following information: the reporter stated the problem was caused by a slight pneumatic leak on the airplane side of the pneumatic ground service connection. The reporter said a portion of the forward keel beam sensor loop was found improperly positioned 12 inches from the leak and was repositioned to the correct location.

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Original NASA ASRS Text

Title: A B737-400 IN CRUISE AT FL350 DECLARED AN EMER AND DIVERTED DUE TO R WING BODY OVERHEAT WARNING AND MASTER CAUTION ILLUMINATED.

Narrative: WE WERE WORKING FLT ENRTE FROM ZZZ1 TO ZZZ3. AT LEVEL OFF THE MASTER CAUTION AND THE AIR CONDITIONING LIGHTS ILLUMINATED. LOOKING AT THE AIR CONDITIONING PANEL THE R WING BODY OVERHEAT LIGHT WAS ILLUMINATED. I CALLED FOR AND THE CAPT COMPLETED THE WING BODY OVERHEAT CHKLIST FROM THE QRH. THE LIGHT DID NOT EXTINGUISH EVEN AFTER ISOLATING THE R SIDE. IT REMAINED ILLUMINATED AND KEPT RESETTING THE MASTER CAUTION LIGHT. AT THAT POINT WE DECLARED AN EMER WITH CENTER AND REQUESTED AND LNDG AT ZZZ. DUE TO OUR ALT AND LOC, ZZZ2 AND ALL THE ARPTS IN THE AREA WERE EQUAL TIME AWAY. WE DECIDED ON ZZZ DUE TO THE MAINT FACILITIES, AREA MEDICAL FACILITIES, AND ZZZ RWY. WE LANDED WITHOUT INCIDENT, STOPPED THE ACFT ON THE RWY, AND SHUT DOWN THE NUMBER TWO ENGINE. EMER VEHICLES MET THE ACFT AND ADVISED US THAT THEY COULD NOT SEE ANY DAMAGE. WE THEN TAXIED TO THE GATE IN ZZZ. MAINT MET THE ACFT AND DISCOVERED TWO DIFFERENT PROBS. THE FIRST WAS A SMALL BLEED AIR LEAK LOCATED WHERE THE EXTERNAL AIR IS CONNECTED TO THE ACFT, AND ALSO IN ADDITION THEY DISCOVERED A FAULT IN THE DETECTION SYSTEM. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE PROB WAS CAUSED BY A SLIGHT PNEUMATIC LEAK ON THE AIRPLANE SIDE OF THE PNEUMATIC GND SERVICE CONNECTION. THE RPTR SAID A PORTION OF THE FORWARD KEEL BEAM SENSOR LOOP WAS FOUND IMPROPERLY POSITIONED 12 INCHES FROM THE LEAK AND WAS REPOSITIONED TO THE CORRECT LOCATION.

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.