What was found
ENROUTE, ONE HOUR NOTED FUEL REMAINING 2.5K BELOW PLANNED BURN. RECEIVED LEVEL 2 FUEL QUANTITY/USE CHECK AFTER. FOLLOWED QRH. ALL FUEL USED & TANK LEVEL SAME, MISSING 3.5K FUEL NOW. TANK 2 DROPPED FROM 8.7K - 6.5K IN 10-15 MIN, LOSING FUEL FASTER THAN BURN, DIVERTED. NO EVIDENCE OF LEAKS ON POST FLT WALKAROUND. TRANSFERRED FUEL TO EACH TANK NR 1, & 3, VERIFIED QTYS TO BE CORRECT. TRANSFERRED FUEL INTO TANK NR 2, FOUND QTY OFF AS MUCH AS 2.5K LBS WITH 19.6 K LBS ONBOARD, NR 2 TANK READ 22.4K LBS & NR 2 STICK READING 20.8. IAW MM 12-11-07-3-1. REPLACED NR 1 PROBE NR 2 TANK, NR 1 PROBE NR 2 TANK , NR 5 PROBE NR 2 TANK & LT TANK COMPENSATOR PROBE. IAW AMM 28-41-01-4 & AMM 28-41-37-4, TEST PASSED.