FUEL LEAK CAUSES A DIVERT LAND.

Narrative

TAXIED TOOK OFF AND CLBED USING DC-9 CTR TANK FUEL. CTR TANK EMPTIED JUST BEFORE LEVELING OFF AT FL310. WITHIN 10 MINS OF LEVELING OFF; AN 800 LB FUEL IMBAL DEVELOPED (R WING HEAVY); FUEL CROSS-FEED WAS STARTED AT THIS TIME. FUEL USED TOTALIZERS SHOWED SLIGHTLY HIGHER FUEL USE BY R ENG. THE CAPT CHKED THE WING AND SAW FUEL LEAKING FROM TOP. THE DECISION WAS MADE TO DIVERT. WE BOTH CAME UP WITH MKE AS THE DIVERSION ARPT. AT THAT TIME WE WERE CLOSER TO ORD THAN MKE BUT MKE WAS OUR FIRST CHOICE BECAUSE OF CONGESTION AND THE EFFECT OF A SHORT NOTICE EMER ACFT IN THE ORD OP. WE ALSO FELT WE COULD GET INTO MKE QUICKER; AGAIN BECAUSE OF THE MAGNITUDE OF THE ORD OP. AS THE CAPT WAS PERFORMING CHKLIST AND COORDINATING WITH THE COMPANY; I INITIATED THE DIVERT WITH ZAU. I HAD GIVEN ZAU A 'HEADS UP' CALL WHEN THE CAPT FIRST CONFIRMED THE LEAK SO THE TURN TO MKE WAS INSTANTANEOUS AND THE DSCNT QUICKLY FOLLOWED. WHEN CTR ASKED; I SAID WE WERE NOT IN AN EMER SIT BUT THIS WAS A COMPANY DIVERT. I FLEW AN IDLE DSCNT TO MKE ONLY ADDING PWR AFTER THE GEAR AND FLAPS WERE EXTENDED. DURING THE DSCNT; THE CAPT CALLED MKE TWR AND GAVE THEM ANOTHER 'HEADS UP' THAT WE WOULD BE REQUIRING THE EMER EQUIP SO THEY COULD BE IMMEDIATELY AVAILABLE TO TELL US THE STATUS OF THE LEAK AND IN CASE THE SIT WORSENED. ONCE WE WERE HANDED OFF TO MKE TWR; WE DECLARED AN EMER; (PRIMARY AS A PRECAUTION); IN THE EVENT SOMETHING ELSE DEVELOPED. AFTER LNDG; THE EMER VEHICLES RELAYED NO FUEL LEAKS WAS VISIBLE; WE SECURED THE L ENG AS A PRECAUTION AND TAXIED TO THE GATE. A FAILED O-RING ON A FUEL PROBE COVER WAS THE CAUSE OF THE LEAK. MKE HAD A PART; SO WE WERE REPAIRED AND UNDERWAY AGAIN SHORTLY. A PRIMARY REASON FOR SUBMITTING THIS RPT IS TO PROTECT OURSELVES IN THE EVENT SOMEONE FROM THE FAA DECIDES WE DID NOT PROCEED TO THE 'NEAREST SUITABLE ARPT' (IE; ORD). MKE; IN OUR OPINION WAS THE MOST SUITABLE BECAUSE OF THE REDUCED PLT LOAD TO DIVERT THERE AND THE MINIMUM AMOUNT OF ELAPSED TIME (1-TURN TOWARD THE ARPT AND A VISUAL APCH).